Predictors of IDDM recurrence risk in offspring of Danish IDDM patients

Summary It has previously been observed that offspring of mothers with insulin-dependent diabetes mellitus (IDDM) have a lower risk of IDDM than offspring of IDDM affected fathers. To assess the offspring IDDM recurrence risk in a Danish population-based study and to investigate parental and offspring-related biological variables that might influence this risk, we identified 2726 IDDM probands and their 2826 offspring from a background population of 1.725 million people (33 % of the Danish population). Current age of probands was 20–65 years and their age at IDDM onset was 30 years or less. Sixty-nine offspring (2.4 %) were affected with IDDM. The sex difference in the parental-offspring IDDM transmission rate was confirmed. The cumulative IDDM risk up to age 30 years was found to be significantly decreased in maternal offspring compared to paternal offspring (2.3 ± 0.6 and 5.7 ± 0.9 %, RR = 2.40, 95 % CI 1.30–4.47; p = 0.004) only if parents were diagnosed with IDDM before birth of the offspring. However, due to the low number of diabetic offspring of probands diagnosed with IDDM after offspring birth, this observation needs to be confirmed in a larger population. In a subpopulation of the 2380 offspring, whose parents were all diagnosed with IDDM before offspring birth, the recurrence risk was significantly increased in offspring of male probands diagnosed up to age 17 years compared to offspring of fathers diagnosed at older ages (8.5 ± 1.8 and 3.6 ± 1.0 %; RR = 2.27, 95 % CI 1.21–4.25; p = 0.006). No such relation was found in maternal offspring. Using the Cox proportional hazards model on this offspring subpopulation we found that paternal age at IDDM onset was the only statistically significant predictor of IDDM recurrence risk. Our findings may be important for counselling families in which one parent has IDDM. [Diabetologia (1998) 41: 666–673] Received: 14 July 1997 and in revised form: 29 December 1997     

Familial factors determine the development of diabetic nephropathy in patients with IDDM

Summary To evaluate familial factors in the development of diabetic nephropathy in insulin-dependent diabetes mellitus (IDDM) we examined concordance for diabetic nephropathy in families with multiple IDDM siblings. Families (n=110) were identified through Joslin Clinic patients (probands) with a sibling having IDDM. To be eligible, the probands' and siblings' ages at IDDM diagnosis were less than 21 years, and IDDM duration was more than 15 years for probands and more than 10 years for siblings. Mean post-pubertal diabetes duration was 23 years for probands (n=110) and 21 years for siblings (n=125). Nephropathy history was determined by medical record review for deceased patients and those with persistent proteinuria or end-stage renal disease to ascertain the date of onset of persistent proteinuria. For patients without documented nephropathy, the albumin/creatinine ratio was measured in multiple urine samples. The cumulative incidence of persistent proteinuria according to post-pubertal duration of IDDM was determined by life-table analysis. For probands and siblings combined, the cumulative incidence of advanced diabetic nephropathy after 30 years of IDDM was 35%, but the risk in siblings varied according to the proband's renal status. The cumulative risk in siblings after 25 years of IDDM (post-puberty) was 71.5% if the proband had persistent proteinuria but only 25.4% if the proband did not (p<0.001). A difference of nearly 50% in the risk to IDDM siblings, depending upon the IDDM proband's renal status, is consistent with a major gene effect that predisposes an individual with IDDM to develop advanced diabetic nephropathy.Abbreviations IDDM Insulin-dependent diabetes mellitus - C.I. confidence interval     

Evidence for importance of gender and birth cohort for risk of IDDM in offspring of IDDM parents

Summary The risk of developing diabetes is higher in offspring of fathers than of mothers with insulin-dependent diabetes mellitus (IDDM). The reasons for this sex differential are unclear, as early studies were often selected and relatively small. We conducted a prospective study on the risk of IDDM in a cohort of 9,453 offspring from 5,255 Finnish parents with diabetes diagnosed before age 30 years. Age of first admission to the hospital was considered to be the age of diagnosis of IDDM in the offspring; IDDM occurred in 248 offspring. The risk of IDDM tended to be lower in the offspring of the same gender as the diabetic parent (adjusted risk ratio (RR) 0.78; p=0.50). When offspring were of same gender as the diabetic parent, male offspring had a higher risk of IDDM than female offspring (RR 2.28; 95% confidence interval 1.53–3.38), whereas if the gender of the diabetic parent and the offspring were different, the risk in male offspring was lower (RR 0.43; 95% confidence interval 0.31–0.62). For the offspring of diabetic fathers, the cumulative risk by the age of 20 was higher (7.6%) than for those with diabetic mothers (3.5%) (p<0.0001). In a multivariate analysis statistically significant predictors of IDDM in the offspring were the sex of the parent, the year of birth and the birth order of the offspring. The risk of IDDM in the offspring increased by 9% per year of birth cohort. By age 20, the cumulative risk of developing IDDM in the offspring of diabetic parents was 5.3%, 10 times higher than in the background population. It is likely that genetic factors seem to have played a major role in the continuous increase of IDDM incidence in Finnish children.Abbreviations IDDM Insulin-dependent diabetes mellitus - CI confidence interval - RR risk ratio     

The Pittsburgh Insulin-Dependent Diabetes Mellitus (IDDM) study. HLA antigens and haplotypes as risk factors for the development of IDDM in IDDM patients and their siblings

The relationships between HLA antigens, sex, age at diagnosis, season of onset and insulin-dependent diabetes mellitus (IDDM) were studied in a consecutive admissions series of newly-diagnosed IDDM patients at Children's Hospital of Pittsburgh. In agreement with the findings of others, the strongest positive associations between IDDM and HLA antigens were seen with DR3 and DR4 (odds ratios (OR) of 3.5 and 4.4, respectively), while a very strong negative association was observed with DR2 (OR of 0.1). Male patients were significantly more likely than female patients to possess DR3 while female patients were significantly more likely to be DR4+. No consistent relationships were found between HLA antigens and either age at diagnosis or season of onset. Using a life table approach, the cumulative risk of IDDM by age 24 in HLA-identical siblings of IDDM patients was estimated to be 10.3%. This risk was significantly greater than the risks to either HLA-haploidentical siblings (2.2%) or to HLA-nonidentical siblings (1.0%), whose risks were not significantly different. B7 + HLA-identical siblings of patients appeared to be protected from the effects of HLA-identicality--their cumulative risk by age 24 was estimated to be only 2.3%.     

The prevalence of IDDM in the first degree relatives of children newly diagnosed with IDDM in Austria--a population-based study. Austrian Diabetes Incidence Study Group.

Insulin dependent diabetes mellitus shows a strong familial predisposition and an unexplained geographical variation in incidence. It is not known whether the risk of IDDM in first degree relatives depends on the risk in the background population. The aim of the study was to assess the prevalence of IDDM in parents and siblings of newly diagnosed children with IDDM in Austria, a known area of low risk for IDDM. The family history data of all diabetic children (< 15 years) diagnosed between 1988-1994 in Austria were analysed. The cumulative incidence of IDDM in siblings of newly diagnosed diabetic children was 0.0026772 cases/year, this means 29.7 times increased risk compared to the background population. Of the diabetic children 5.8% had at least one parent with IDDM and the prevalence of IDDM in fathers (3.9%) was higher (p = 0.015) compared to mothers (1.9%).The risk of IDDM tended to be higher for offsprings of diabetic fathers (OR 3.8, p < 0.003) in families with 2 or more children than in single child families, where the prevalence was 4.2% both in fathers and mothers. In conclusion the prevalence of IDDM in parents of diabetic children in Austria was lower than reported in populations with high IDDM incidence. This may reflect a lesser degree of genetic predisposition of the Austrian population. The prevalence of IDDM in siblings was similar to that in high risk populations. We saw an interaction of gender of the diabetic parent and diabetic offspring and the family size.     

Natural history of preclinical IDDM in high risk siblings

Summary To learn more about the preclinical phase of IDDM we observed for a median period of 46.5 months (range 0.5–69 months) a group of 57 siblings positive for ICA and/or IAA when first screened within 6 months of the diagnosis of the proband. Sequential blood samples and IVGTTs were obtained at intervals of 6–12 months. Seventeen siblings (29.8%) presented with IDDM during the observation period. The duration of the known preclinical period ranged from 0.5 to 51 months (median 29 months). The converters were younger than the other siblings (P<0.05) and had higher initial ICA levels (P<0.01). In addition they had a lower FPIR in the first IVGTT (P<0.001). On all subsequent tests the converters had higher ICA levels and a lower FPIR (P<0.05 or less), a lower glucose elimination rate from the third test onwards (P<0.01 or less) and higher IAA levels at 3 years (P<0.05). Some variation could be observed in the FPIR in the converters with an initial increase and subsequent decrease (P<0.05 for both). Their levels of complement-fixing ICA increased up to 18 months (P<0.05) and IAA levels up to 3 years (P<0.01). Those high risk siblings who progress to clinical IDDM are characterized by young age, strong and increasing signs of islet-cell specific autoimmunity, reduced insulin secreting capacity and emerging glucose intolerance. The present observations seem to be incompatible with the hypothesis of beta-cell destruction occurring at a constant, predictable rate.Abbreviations IDDM Insulin-dependent diabetes mellitus - ICA islet cell antibodies - IAA insulin antibodies - IVGTT intravenous glucose tolerance test - FPIR first phase insulin response - JDF Juvenile Diabetes Foundation     

IDDM2/insulin VNTR modifies risk conferred by IDDM1/HLA for development of Type 1 diabetes and associated autoimmunity

AIM/HYPOTHESIS: Type 1 diabetes (T1D) is an autoimmune disease with multiple susceptibility genes. The aim of this study was to determine whether combining IDDM1/HLA and IDDM2/ insulin( INS) 5' variable number of tandem repeat locus (VNTR) genotypes improves T1D risk assessment. METHODS: Patients with T1D (n=488), control subjects (n=846), and offspring of parents with T1D (n=1122) were IDDM1 and IDDM2 genotyped. Offspring were followed for islet autoantibodies and T1D from birth until the age of 2 to 12 years. RESULTS: Compared to the I/I INS VNTR genotype, the I/III and III/III genotypes reduced T1D risk conferred by IDDM1/HLA in all HLA genotype categories of the case-control cohort by 1.6-fold to three-fold. The highest T1D risk was associated with INS VNTR class I/I plus HLA DR3/DR4-DQ8 (20.4% in patients, 0.6% in control subjects) or HLA DR4-DQ8/DR4-DQ8 (6.3% in patients, 0.2% in control subjects). In the offspring, HLA DR3/DR4-DQ8 and DR4-DQ8/DR4-DQ8 conferred increased risk for early development of islet autoantibodies (14.6% and 12.9% by age 2 years). Offspring with these high risk IDDM1 genotypes plus the INS VNTR class I/I genotype (n=71; 6.3%) had the highest risk of developing islet autoantibodies (21.8% by age 2 years vs 8.9% in offspring with high risk IDDM1 plus INS VNTR class I/III or III/III genotypes, p<0.05) and T1D (8.5% by age 6 years vs 4.3%). Offspring who developed autoantibodies to multiple antigens had increased frequencies of both high risk IDDM1 and IDDM2 genotypes (p<0.0001), whereas offspring who developed autoantibodies to GAD only had increased frequencies of high risk IDDM1 and protective IDDM2 genotypes, suggesting that IDDM2 influences the autoimmune target specificity. CONCLUSION/INTERPRETATION: Combining IDDM1 and IDDM2 genotyping identifies a minority of children with an increased T1D risk.     

Prevalence of inflammatory bowel disease in family members of Jewish Crohn's disease patients in Israel

A familial study of 189 Jewish Crohn's disease patients was conducted in order to evaluate the risk for inflammatory bowel disease (IBD) in relatives of the patients and to try to understand better the genetic component in the etiology of the disease among Jews. One hundred fifty-seven patients filled out questionnaires that were verified by personal interviews. In 10 families (6.6%), a first-degree relative of the propositus was found to have IBD, seven Crohn's disease and three ulcerative colitis. Among first-degree relatives, siblings were more frequently affected: of 400, five had Crohn's disease and one ulcerative colitis. Among 304 parents, two had Crohn's disease and two ulcerative colitis, while none of the propositi's children had IBD. The prevalence of first-degree relatives with Crohn's disease was similar in the 98 and 45 families of Ashkenazi and non-Ashkenazi origin: 5.1% and 4.4%, respectively. The risk for siblings of the probands to be affected were also similar in the two groups: 1.5% and 1.8%; while parents of the probands were affected only in the group of Ashkenazi Jews.     

Premature cardiovascular disease is common in relatives of patients with premature peripheral atherosclerosis

BACKGROUND: Numerous clinical conditions have been proposed to explain the premature onset of symptomatic peripheral vascular disease (PVD) in young adults, but the role of genetic factors has not been defined. This study was performed to determine the prevalence of cardiovascular disease among family members of patients with premature PVD. METHODS: The prevalence of early cardiovascular events occurring in first-degree relatives of 90 subjects with premature PVD (onset < or =49 years) was determined. The prevalence of occult atherosclerosis was determined by duplex ultrasonography in a cohort of 20 asymptomatic siblings. Reference groups included first-degree relatives of 80 subjects with premature coronary artery disease (CAD) and first-degree relatives of 48 healthy subjects. RESULTS: Cardiovascular events occurred at age 55 years or younger in 28% of the parents of PVD subjects, in 23% of parents of CAD subjects, and in 7% of the parents of healthy controls (P<.001). Cardiovascular events occurred in 24% of siblings of PVD subjects, in 14% of siblings of CAD subjects, and in 7% of siblings of healthy controls (P<.001). Duplex ultrasonography detected early plaques in the lower extremity circulation of 10 (50%) of the asymptomatic siblings of PVD subjects. CONCLUSIONS: Early, symptomatic cardiovascular disease is more common in first-degree relatives of individuals with premature PVD than in relatives of healthy individuals or of probands with premature CAD. Occult vascular disease in the lower extremity is prevalent among asymptomatic siblings of probands with premature PVD. These observations indicate that susceptibility to premature PVD has a familial basis.     

Autoantibodies against sympathetic ganglia and evidence of cardiac sympathetic dysinnervation in newly diagnosed and long-term IDDM patients

Summary To investigate the presence of autoantibodies against sympathetic nervous tissue and their correlation with cardiac sympathetic dysinnervation in insulin-dependent diabetes mellitus (IDDM), 20 newly diagnosed (age 26±6 years) and 48 long-term IDDM patients (age 40±13 years, duration of diabetes 22±12 years) without myocardial perfusion abnormalities (normal ^99mTC-methoxyisobutylisonitrile uptake) were assessed for myocardial ¹²³I-metaiodobenzylguanidine (¹²³I-MIBG) uptake and complement-fixing sympathetic ganglia (CF-SG) autoantibodies. Both groups of patients were also studied for islet cell antibodies (ICA) and ECG-based cardiac autonomic neuropathy. Eighty control subjects (age 18–49 years) were investigated for CF-SG autoantibodies. Eight newly diagnosed (40%) and 12 long-term (25%) IDDM patients exhibited CF-SG autoantibodies, compared to 4 control subjects (5%; p<0.01, p<0.05). In long-term diabetic patients, the reduction of global but not of regional myocardial ¹²³I-MIBG uptake correlated with CF-SG autoantibodies (r=0.34, p=0.02). Newly diagnosed diabetic patients did not show an association between CF-SG autoantibodies and global or regional myocardial ¹²³I-MIBG uptake. ECG-based cardiac autonomic neuropathy ( two of five cardiac reflex tests abnormal) was present in 22 and absent in 26 long-term IDDM patients, of whom 9 (41%) and 3 (12%), respectively were positive for CF-SG autoantibodies (p=0.02). Only 1 newly diagnosed IDDM patient demonstrated ECG-based cardiac autonomic neuropathy and was also positive for CF-SG autoantibodies. Although they are somewhat suggestive, results concerning autoantibodies against sympathetic nervous tissue and cardiac sympathetic dysinnervation do not strongly support the view that autoimmune mechanisms play a major role in the pathogenesis of cardiac sympathetic neuropathy in IDDM.Abbreviations MIBG Metaiodobenzylguanidine - SPECT single-photon emission computed tomography - CF-SG complement-fixing sympathetic ganglia - MIBI methoxyisobutylisonitrile - ICA islet cell antibodies - MU myocardial uptake     

Familial occurrence of abdominal aortic aneurysm

BACKGROUND: A family history of abdominal aortic aneurysm has been reported to increase the risk for developing the disease. OBJECTIVE: To determine the risk for abdominal aortic aneurysm in first-degree relatives of patients with the disease. DESIGN: Cross-sectional ultrasonographic screening study. SETTING: University Central Hospital, Helsinki, Finland. PATIENTS: 238 of 325 living first-degree relatives of patients having surgery for abdominal aortic aneurysm (age > 50 years; 98 men and 110 women) and 281 controls (135 men and 149 women) without a family history of abdominal aortic aneurysm. MEASUREMENTS: Ultrasonography was used to measure aortic diameter in 101 male relatives and 140 female relatives (241 of the 325 persons at risk [74%]) and in 281 controls. RESULTS: Three siblings had already undergone surgery for abdominal aortic aneurysm. Eleven siblings (all brothers) (11 of 101 [10.9%]) had ultrasonographic evidence of abdominal aortic aneurysm (aortic diameter > 30 mm). In the control group, 2 men (1.5%) and 2 women (1.3%) had an aneurysm. Thirty siblings and no controls had dilatation of the abdominal aorta (aortic diameter, 20 to 29 mm). Neither the age nor the sex of the proband affected risk for developing abdominal aortic aneurysm among first-degree relatives. Family history increased the risk for an aneurysm by 4.33-fold (95% CI, 1.32-fold to 14.23-fold), male sex increased the risk by 12.21-fold (CI, 2.63-fold to 56.64-fold), and age (by decade) increased the risk by 1.93-fold (CI, 1.15-fold to 3.25-fold). CONCLUSION: Aging brothers of patients with known abdominal aortic aneurysm have the highest risk for developing the disease; the prevalence of the disease in siblings older than 60 years of age is 18%.     

Familial occurrence of inflammatory bowel disease in Korea

BACKGROUND: Little information is available about the familial aggregation of inflammatory bowel disease (IBD) in Asian populations. We therefore determined the risk of familial aggregation of IBD among first-degree relatives of patients with ulcerative colitis (UC) or Crohn's disease (CD) in an ethnically distinct Korean population. METHODS: Familial aggregation of IBD was evaluated in terms of family history, prevalence, lifetime risk, and population relative risk in first-degree relatives of 1440 unrelated patients with UC (n = 1043) or CD (n = 397). RESULTS: A positive first-degree family history of IBD was observed in 27 probands (1.88%): 21 of 1043 (2.01%) with UC and 6 of 397 (1.51%) with CD. The crude prevalence of IBD in first-degree relatives of probands with IBD was 0.31%. The lifetime risk of IBD was 0.54% in all first-degree relatives of IBD probands, 0.52% in UC probands, and 0.67% in CD probands, with overall lifetime relative risks of 0.12% in parents, 0.79% in siblings, and 1.43% in offspring. The age- and sex-adjusted population relative risk of IBD was 13.8 in first-degree relatives of probands with IBD. CONCLUSIONS: Although a positive family history, prevalence, and lifetime risk of IBD among first-degree relatives of Korean IBD patients are much lower than among relatives of Western patients, the population relative risk in first-degree relatives is about equal in Koreans and Westerners. This finding indicates that a positive family history is an important risk factor for IBD in Koreans and in Westerners.     

Comparison of patients by family history with gastric and non-gastric cancer

AIM： To compare the gastric cancer （GC） patients by their family history with gastric and non-GC.
METHODS： Positive family histories within seconddegree relatives and clinicopathological features were obtained for 256 patients.
RESULTS： Of the 256 probands, 112 （76 male, 36 female） were incorporated into familial GC （FGC） group： at least two GC members; 144 （98 male, 46 female） were included in the non-FGC group （relatives only affected with non-GCs）. Of 399 tumors in relatives （181 from FGC against 212 from non-FGC）, GC was the most frequent, followed by esophageal, hepatocellular, and colorectal cancer. Nasopharyngeal cancer was next to lung cancer but prior to breast and urogenital cancers. Most affected members aggregated within first-degree relatives （FGC： 66 siblings, 48 fathers, 31 mothers, four offspring; non-FGC： 56 fathers, 55 siblings, 43 mothers, and 15 offspring）. The ratio of males to females in affected first-degree relatives was usually higher in male probands. Paternal history of GC was a slight risk for GC in males （OR = 1.19, 95% CI： 0.53-2.69）, while risk of GC by maternal history of nonGCs was increased in females （OR = 0.46, 95% CI： 0.22-0.97）. Diffuse-GC was the major histological type in all subgroups. Difference in tumor sites between the two groups was derived from an excess of upper sites in non-FGC female probands.
CONCLUSION： Distribution of associated non-GCs in a family history of GC may vary with geographic areas. GC may have different genetic and/or environmental etiology in different families, and a certain subtype may be inherited in a female-influenced fashion.     

Concordance of familial characteristics in Crohn's disease and ulcerative colitis

The diagnosis of inflammatory bowel disease (IBD) in a proband increases the probability of a parallel IBD diagnosis in a family member. In this study, we were able to confirm the IBD diagnosis in 35 (9.9 percent) of the relatives of 352 registry probands. To confirm a proband's report of a positive family history of IBD, efforts were made to directly contact all first-degree relatives regardless of their IBD status (parents, siblings, and children). Consent to contact family members was obtained from the proband, who furnished the registry personnel with names, addresses, and phone numbers. We then attempted to contact each identified relative by phone. After verbal consent was obtained, family members were asked if they had been diagnosed with IBD. This diagnosis was confirmed by contacting the relative's physician. A McNemar (² _Mc) matched-pair analysis was used to analyze concordance between the proband and the affected family member. Within the CD/CD (Crohn's disease) concordant pairs, sex was a significant risk factor. Sex was not a significant risk factor within the UC/UC (ulcerative colitis) concordant pairs. In the condordant surgery pairs, no surgical procedure was a significant risk factor for the prediction of a similar surgical procedure for the affected relative. In concordant extraintestinal complications, only the appearance of a skin rash was significantly related to the appearance of a skin rash in the affected relative.Supported by a grant from The Dorothy Rider Pool Health Care Trust.     

Clustering of colorectal cancer in families of probands under 40 years of age

Although sporadic colorectal cancer (CRC) is relatively uncommon in the young, it may constitute an elevated genetic risk for CRC in these individuals. PURPOSE: This study was designed to determine extent of colorectal cancer in families of probands under 40 years of age. METHODS: Medical records of all consecutive patients, 40 years of age or younger at the time of CRC surgery, during the time period 1986 to 1994 were examined. Cases of familial adenomatous polyposis and ulcerative colitis were excluded.Via interviews of surviving probands or nearest relatives, dates of birth and death, causes of death, and diagnosis of cancer were recorded on all first-degree relatives (parents, siblings, and offspring), second-degree relatives (grandparents, aunts, and uncles), and any other relatives. RESULTS: A total of 128 patients, 40 years of age or less at time of CRC resection, were identified. Of these, 45 probands/families were reached by phone, and 45 detailed family histories were obtained. Age range of these 45 probands was 19 to 40 (mean, 33.1) years. In 25 families there was no history of CRC in first-degree, second-degree, or third-degree relatives. Eight of 45 probands (17.8 percent) had at least one first-degree relative with CRC, and three of these eight families fulfilled the Amsterdam criteria for hereditary nonpolyposis colorectal cancer (HNPCC). In all three families, inheritance of CRC appeared to segregate with the maternal side of the family. In addition, 5 of 43 non-HNPCC probands had at least one first-degree, second-degree, or third-degree relative less than 40 years of age, at time of CRC diagnosis. CONCLUSION: Ascertainment of a detailed family history in early age of onset CRC patients identifies frequent familial clustering of CRC and HNPCC in 17.8 percent of cases.Dr. Guillem is recipient of a Career Development Award from the American Cancer Society and a research grant from The New York District Council of Carpenters Benefits Fund.Poster presentation at the meeting of The American Society of Colon and Rectal Surgeons, Montreal, Quebec, Canada, May 7 to 12, 1995.     

Linkage of rheumatoid arthritis with HLA.

OBJECTIVE--To determine whether HLA exerts a variable influence on the predisposition of siblings of probands with clinically mild and severe rheumatoid arthritis (RA). METHOD--Calculation of crude and adjusted odds ratios for concordance rates in sibships sharing two, one and no HLA haplotypes with a proband with clinically mild and severe RA, and HLA haplotype sharing in multiply affected sibships in the same clinical groups. RESULTS--Compared with a reference value of 1.0 in siblings sharing no HLA haplotypes with a proband with mild RA, siblings sharing two HLA haplotypes with a severely affected proband had a sibship concordance rate odds ratio of 9.7 (95% confidence interval 2.5 to 38.2). When adjusted for age, sex, and disease duration, the odds ratio was 7.6 (1.8 to 32.4). No other sibships showed concordance rates which were significantly higher than the reference group. HLA haplotype sharing in multiply affected sibships in which the proband had severe RA deviated significantly from random (two, one, and no HLA haplotypes shared: 53.3, 40, and 6.7%, respectively; expected 25, 50, and 25%), whereas in sibships of probands with mild RA they did not (14.6, 70.8, and 14.6%). CONCLUSIONS--In the predisposition of siblings to RA, sharing HLA haplotypes with a proband is only important if the proband has severe RA. Mild RA is not genetically linked to the HLA region.     

Fertility is reduced in women and in men with type 1 diabetes: results from the Type 1 Diabetes Genetics Consortium (T1DGC)

Aims/hypothesis

A recent Finnish study described reduced fertility in patients with childhood-onset type 1 diabetes. The Type 1 Diabetes Genetics Consortium (T1DGC) is an international programme studying the genetics and pathogenesis of type 1 diabetes that includes families with the disease. Our aim was to assess fertility, defined as number of offspring, in the affected and unaffected siblings included in the T1DGC.

Methods

Clinical information from participants aged ≥18 years at the time of examination was included in the present analysis. The number of offspring of affected and unaffected siblings was compared (in families including both) and the influence of birth year, disease duration and age of onset was assessed, the last in affected siblings only, using Poisson regression models.

Results

A total of 3010 affected and 801 unaffected adult siblings that belonged to 1761 families were assessed. The mean number of offspring was higher in the unaffected than in the affected individuals, and the difference between the two groups was more pronounced in women than men. Poisson regression analysis showed that both sex and birth cohort significantly affected the differences between groups. In the affected siblings, adult onset (≥18 years), female sex and older birth cohort were associated with higher fertility.

Conclusions/interpretation

Patients with type 1 diabetes have fewer children than their unaffected siblings. This effect is more evident in women and in older birth cohorts. Onset of type 1 diabetes as an adult rather than a child is associated with a higher number of offspring, even after accounting for birth cohort and disease duration.     

Longitudinal analysis of somatic development in paediatric patients with IDDM: genetic influences on height and weight

Summary Normal growth and development, as well as the prevention of overweight, are major goals in the treatment of paediatric patients with insulin-dependent diabetes mellitus (IDDM). We therefore evaluated longitudinally the anthropometric measurements of height and weight, as well as bone age, in an unselected group of 389 patients with IDDM treated at one institution. In order to identify genetic influences on these parameters, height and weight were determined in 186 unaffected siblings and 177 pairs of parents. At diagnosis, patients were slightly taller than average (median z score: +0.37). During the subsequent course of diabetes, age-adjusted heights decreased progressively for the first 9 years, catching up again after more than 10 years of diabetes. Bone ages were progressively retarded with increasing duration of diabetes. In 76 patients of 18 years or older, median z-score for height was +0.30, not different from their unaffected siblings (median z-score: +0.22). The correlation with midparental height was identical for diabetic and nondiabetic siblings (r=0.43). In contrast, children with diabetes were significantly heavier (z-score for weight: +0.74 compared to +0.34 in unaffected siblings; p<0.002). Obesity developed primarily during and after puberty. We conclude that: 1) during the course of diabetes, longitudinal growth is temporarily reduced and maturation is delayed in children with diabetes compared to unaffected siblings. However, this effect of diabetes is transient and small compared to genetic influences on height in an individual child. 2) As a group, children with IDDM become significantly overweight, which is likely to increase the cardiovascular risk during adulthood.Abbreviations BA Bone age - CA chronological age - GH growth hormone - IGF-I insulin-like growth factor I - NPH neutral protamin Hagedorn-insulin - SDS standard deviation score (z score) - IDDM insulin-dependent diabetes mellitus - BMI body mass index     

Recurrence risks in children having one parent with a congenital heart disease.

The risk of recurrence of a congenital cardiovascular malformation in a child having one parent with congenital heart disease has been determined for each of the seven most common anomalies presently compatible with survival to reproductive age. The range of risk is 2.5% to 4.3% depending on the lesion. This is within the range of expectation for the model of multifactorial inheritance previously used to predict recurrence in other first-degree relatives of probands (siblings and parents) with congenital heart disease. The cardiovascular abnormality occurring in the child was most often the same as in the parent or was a closely related variant of it.     

Lack of preservation of higher brain function during hypoglycaemia in patients with intensively-treated IDDM

Summary Severe hypoglycaemia with cognitive dysfunction is 3 times more common in intensively, rather than conventionally, treated insulin-dependent diabetes mellitus (IDDM). To investigate the effect of diabetes control on higher brain function during acute hypoglycaemia, we studied one of the earliest detectable changes in cognitive function, i.e. the four-choice reaction time, and symptomatic and hormonal responses during euglycaemic and hypoglycaemic clamping in human subjects. There were no changes in symptoms or counterregulatory hormones and four-choice reaction time was stable during 220 min of euglycaemic insulin clamping in five men with IDDM, with a coefficient of variation of less than 2.2% (1% for accuracy) for the cognitive function test. During stepped hypoglycaemic clamping however, hormonal responses and subjective awareness of hypoglycaemia occurred in all groups but started at much lower blood glucose concentrations in eight intensively-treated diabetic subjects (Group 1) than in ten conventionally-treated (Group 2) or in eight non-diabetic subjects (Group 3). For example, for adrenaline, plasma glucose thresholds were 2.7±0.2 vs 3.4±0.2 and 3.2±0.1 mmol/l, respectively, p<0.05, Group 1 vs Groups 2 or 3 and for subjective awareness of hypoglycaemia 2.3±0.2 vs 3.0±0.1 and 3.2±0.1 mmol/l, p 0.003), as in previous studies. In contrast, deterioration in reaction time occurred at 3.2±0.3, 3.2±0.2 and 3.0+0.2 mmol/l, respectively (p=NS), thus occurring at higher glucose levels than subjective awareness in the intensively-treated subjects only. The altered hierarchy of responses to hypoglycaemia in well-controlled intensively-treated diabetes explains the increased risk of severe hypoglycaemia without warning seen in such patients.Abbreviations IDDM Insulin-dependent diabetes mellitus