Bimodal month of birth distribution in cystic fibrosis

The month of birth of 923 patients in England and Wales dying with cystic fibrosis as an underlying cause was found to be distributed independently of sex and year of birth during 1954–1976. When adjusted for the monthly variations in births in the national population, birth frequencies were bimodally distributed. This confirmed results obtained previously in the Netherlands and Australia. Peak births occurred in late February and August, regardless of whether a single six-monthly cycle or two annual cycles were assumed. It was not possible to choose the better of these models, each yielding similar parametric estimates.     

Season is associated with Pseudomonas aeruginosa acquisition in young children with cystic fibrosis

Pseudomonas aeruginosa, the principal respiratory pathogen in cystic fibrosis (CF) patients, is ubiquitous in the environment. Initial P. aeruginosa isolates in CF patients are generally environmental in nature. However, little information regarding seasonality of P. aeruginosa acquisition is available. We conducted a retrospective study to evaluate the seasonality of initial P. aeruginosa acquisition in young children with CF in the USA using the Cystic Fibrosis Foundation National Patient Registry from 2003 to 2009. Additionally, we assessed whether seasonal acquisition varied by climate zone. A total of 4123 children met inclusion criteria and 45% (n = 1866) acquired P. aeruginosa during a mean 2.0 years (SD 0.2 years) of follow up. Compared with winter, increased P. aeruginosa acquisition was observed in summer (incidence rate ratio (IRR): 1.22; 95% CI: 1.07–1.40) and autumn (IRR: 1.34; 95% CI: 1.18–1.52), with lower acquisition observed in spring (IRR: 0.81; 95% CI: 0.70–0.94). Seasonal variations in P. aeruginosa acquisition rates in the temperate and continental climate zones were similar to those in the overall cohort. In contrast, no significant seasonal effect was observed in the dry climate zone. In a corresponding analysis, no seasonal difference was observed in the rate of acquisition of Staphylococcus aureus, another common CF respiratory pathogen. These results provide preliminary support that climatic factors may be associated with initial P. aeruginosa acquisition in CF patients. Investigation and identification of specific risk factors, as well as awareness of seasonal variation, could potentially inform clinical recommendations including increased awareness of infection control and prevention strategies.     

Identification of SNPs in the cystic fibrosis interactome influencing pulmonary progression in cystic fibrosis

There is growing evidence that the great phenotypic variability in patients with cysticfibrosis (CF) not only depends on the genotype, but apart from a combination ofenvironmental and stochastic factors predominantly also on modifier gene effects. It hasbeen proposed that genes interacting with CF transmembrane conductance regulator (CFTR)and epithelial sodium channel (ENaC) are potential modifiers. Therefore, we assessed theimpact of single-nucleotide polymorphisms (SNPs) of several of these interacters on CFdisease outcome. SNPs that potentially alter gene function were genotyped in 95well-characterized p.Phe508del homozygous CF patients. Linear mixed-effect model analysiswas used to assess the relationship between sequence variants and the repeatedmeasurements of lung function parameters. In total, we genotyped 72 SNPs in 10 genes.Twenty-five SNPs were used for statistical analysis, where we found strong associationsfor one SNP in PPP2R4 with the lung clearance index (P≤0.01), thespecific effective airway resistance (P≤0.005) and the forced expiratoryvolume in 1 s (P≤0.005). In addition, we identified one SNP inSNAP23 to be significantly associated with three lung function parameters aswell as one SNP in PPP2R1A and three in KRT19 to show a significantinfluence on one lung function parameter each. Our findings indicate that directinteracters with CFTR, such as SNAP23, PPP2R4 and PPP2R1A, may modify the residualfunction of p.Phe508del-CFTR while variants in KRT19 may modulate the amount ofp.Phe508del-CFTR at the apical membrane and consequently modify CF disease.     

Increased frequency of cystic fibrosis among infants with jejunoileal atresia

There appears to be an increased frequency of cystic fibrosis (CF) among infants with jejunoileal atresia (JIA). However, the figures vary widely, and no population-based data exist. The purpose of this study was to quantitate the magnitude of the association between JIA and CF in Atlanta using population-based data from 1968 to 1995. Case subjects included all infants with isolated JIA born during 1968–1995 to mothers residing in the five-county metropolitan Atlanta area at the time of birth. To ascertain cases, we reviewed records of the Metropolitan Atlanta Congenital Defects Program (MACDP), a population-based birth defects registry. Caucasian JIA cases were cross-referenced with patients in the CF registry at the Egleston Cystic Fibrosis Center at Emory University to more completely ascertain the diagnosis of CF among JIA cases. During 1968–1995, MACDP ascertained a total of 94 isolated JIA cases, for a birth prevalence of 1.8/10,000 live births. Among the cases, 38 were Caucasian, 52 were African-American, and 4 were of Asian or Hispanic ethnicity. Four of the 38 Caucasian JIA cases (11%) also had CF. The expected number of JIA cases with CF is 0.019 based on the estimated population incidence of 1/2,000 for CF. The observed to expected (O/E) ratio of Caucasian JIA cases with CF is greater than 210 (P < 0.0001). Caucasian infants with JIA have more than 210 times the risk for CF compared with Caucasian infants in the general population. The results of this study have implications for the management of infants born with JIA and genetic counseling for families with affected infants. Am. J. Med. Genet. 78:446–449, 1998. Published 1998 Wiley-Liss, Inc.

1 This article was prepared by a group of United States government employees and non-United States government employees, and as such is subject to 17 U.S.C. Sec. 105.

     

Parental response to cystic fibrosis: a contextual analysis of the diagnosis phase.

A contextual framework guided the measurement of specific stressors encountered by parents of children recently diagnosed with cystic fibrosis (CF). Three variables were assessed within the context of the parenting role: illness-specific tasks, normal parenting tasks, and strains in family roles. These situation-specific stressors were contrasted with global measures of parenting stress in their ability to predict depression. Sixty-four parents (36 mothers, 28 fathers) of infants and toddlers recently diagnosed with CF completed a structured interview and standardized measures in the home. Parents reported elevations in both situation-specific and global parenting stress, and a greater number of depressive symptoms than a norm group. Mothers reported significantly greater strain in managing their caregiving role and higher levels of depression than fathers. Controlling for situation-specific parenting stress and marital satisfaction, regression analyses indicated that role strain related to CF was associated with greater depression in mothers, but not fathers. Furthermore, stressors measured contextually rather than globally accounted for substantially greater proportions of the variance in depression. The findings highlight the need to measure ongoing strains specific to the medical condition, and to assess role-related changes.     

Geographic distribution and regional origin of 272 cystic fibrosis mutations in European populations

The geographic distribution of 272 cystic fibrosis (CF) mutations has been studied by assessing the origin of 27,177 CF chromosomes from 29 European countries and three countries from the North of Africa. The 5 most common mutations are ΔF308 (66.8%), G542X (2.6%), N1303K (1.6%), G551D (1.5%) and W1282X (1.0%). The ΔF508 mutation has the highest relative frequency in Denmark (87.2%) and the lowest in Algeria (26.3%). Mutation G542X is common in the Mediterranean countries, with a mean frequency of 6.1%. N1303K is found in most of the western and Mediterranean countries and has the highest frequency in Tunisia (17.2%). The wide distribution of these mutations suggests an ancient origin. G551D is common in north-west and central Europe, but is uncommon in other parts of Europe. W1282X has the highest frequency in Israel (36.2%), being also common in most Mediterranean countries and north Africa. Seventeen mutations have frequencies between 0.1 and 0.9%, 1717-1G→A (0.83%), R553X (0.75%), R1162X (0.51%), 621+1G→T (0.54%) and 2183AA→G (0.36%), being the most common ones. Some mutations reach relatively high frequencies in some extended geographic regions, such as mutation 394delTT in northern Europe (1.1-28.8%), R117H in northwestern Europe (1.3-3.0%), R553X in central Europe (1.1-24.4%), 1717-1G→A in Belgium and France (1.1-5.3%), and 2183AA→G in Italy and Greece (3.2%). Other mutations are only common in small regions: T338I (Sardinia), 711+1G→T (Tunisia), R1162X (Algeria and north of Italy), 1609delCA (east of Spain), 1811+1.6kbA→G (southeastern Spain), R1066C (Portugal), S549R (Algeria), R334W (Crete), 621+1G→T (Central Greece), 3849+10kbC→T (Israel), 2789+5G→A (south of Greece), 451+1G→A (Israel), R347P (south of Bulgaria), 1677delTA (south of Bulgaria and Turkey), G85E (south of Greece), R347H (Turkey), 3905insT (Switzerland), 1078delT (Brittany), 1898+1G→A (Wales), A455E (The Netherlands), ΔI507 (Brittany), 3659delC (Sweden) and R560T (northern Ireland). Most of these mutations must have an origin and diffusion in the specific European population subgroup. Overall 55 mutations are common in one or several countries or regions of Europe and 217 mutations are rare with relative frequencies of lower than 1% in any of these regions and countries. This information might facilitate mutation analysis of CF in the different regions of Europe. Hum Mutat 10:135–154, 1997. © 1997 Wiley-Liss, Inc.     

Phenotypic heterogeneity in cystic fibrosis

We have confirmed heterogenity in CF using a different combination of primary clinical variables than those used in previous studies. Subgroupings of individuals with similar levels of sweat chloride were independent of the clustering based on level of pancreatic enzyme supplementation and degree of pulmonary involvement. Data from families with multiple CF children are consistent with the hypothesis that the genetic etiology of CF involves two or more genes that modify the expression of the primary gene defect.     

Isoelectric focusing of serum in genetic counselling of families with cystic fibrosis

The high incidence of carriers of cystic fibrosis in the general population allows application of a less than perfect test to genetic counselling of relatives of children with the disorder and their spouses. In the absence of a definitive carrier detection test, we employ isoelectric focusing of serum in this way and include the a priori chance of carrier status in calculating the risk. The test will eventually be replaced but for the present is preferable in our hands to counselling based simply on the known gene frequency.     

Molecular basis of cystic fibrosis in the Republic of Macedonia

Petreska L, Koceva S, Plaseska D, Chernick M, Gordova-Muratovska A, Fustic S, Nestorov R, Efremov GD. Molecular basis of cystic fibrosis in the Republic of Macedonia. Clin Genet 1998: 54: 203–209. 0 Munksgaard, 1998
Eighty-three cystic fibrosis (CF) patients and their families, belonging to various ethnic groups living in the Republic of Macedonia were studied for molecular defects in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, and for the associated extragenic marker loci XV-2c and KM 19. The DNA methodology used included characterization of CFTR mutations in 19 exons (and flanking sequences) of the gene and analysis of distribution of the XV-2c/KM19 haplotypes among normal (N) and CF chromosomes by polymerase chain reaction (PCR) amplification followed by dot blot hybridization, restriction digestion, single-strand conformational polymorphism, constant denaturing gel electrophoresis, denaturing gradient gel elec-trophoresis, and sequencing. We identified 58.4% (97/166) of the CF chromosomes. Nine different CFTR gene mutations, including three novel ones. were found. Eight known and one new CFTR intragene polymorphisrns were also characterized. The haplotype analysis of the XV-2c/TaqI and KM19/PstI polymorphic loci have shown that haplotype C is the most frequently found haplotype among the non-AF508 CF chromosomes from Macedonia (36.5%). The results demonstrate the broad heterogeneity of CF origin in this part of the Balkan Peninsula.     

Novel CFTR mutations in black cystic fibrosis patients

Cystic fibrosis (CF) is considered as a rare disease in black Africans. In fact, this disease is likely to be underestimated since clinical features consistent with CF diagnosis are often ascribed to environmental factors such as malnutrition. Very little is known about CFTR mutations in affected patients from Central Africa. We report here four novel mutations, i.e., IVS2 + 28 (intron 2), 459T > A (exon 4), EX17a_EX18del (exons 17-18), and IVS22 + IG > A (intron 22), in such patients. An update of CFTR mutations reported in black patients from various ethnies is included. These data might be helpful for genetic counselling regarding CF in black patients.     

Antibodies to gastroenteritis viruses in cystic fibrosis patients

Infectivity of certain enteric viruses including rotavirus is profoundly affected by proteolytic enzymes. To test whether cystic fibrosis patients, possessing chronically decreased levels of pancreatic enzymes, show altered susceptibility to gastroenteritis viruses, we examined sera from patients and controls for antibodies to two major pathogens. In cystic fibrosis patients, normal rotavirus antibody levels were found and Norwalk virus antibody prevalence was unchanged.     

Endocrine and exocrine pancreatic function and the ΔF508 mutation in cystic fibrosis

The relationship between the cystic fibrosis (CF) genotype and endocrine and exocrine pancreatic function was studied in 215 CF patients. In the 211 patients with the delta F508 mutation, endocrine pancreatic function (oral glucose tolerance; WHO criteria) was normal in 72.5%, impaired in 12.3%, and diabetic in 15.2% of the patients, with no difference between CF patients homozygous (N = 163, median age 15 years, range 2-40) or heterozygous (N = 48, 18 years, 3-40; age difference not significant) for the delta F508 mutation. Exocrine pancreatic sufficiency (no need for pancreatic enzyme substitution) was found in 0.6% of the patients homozygous for the delta F508 mutation and in 10.4% of the heterozygotes (p less than 0.01). Homozygous patients with pancreatic insufficiency took more pancreatic enzyme capsules (median 42 per day, range 0-192) than the heterozygotes (29 per day, 0-300; p less than 0.001). The four patients (1.9%) without the delta F508 mutation had normal glucose tolerance but exocrine pancreatic insufficiency. In conclusion, the major mutation genotype in CF (delta F508) affects the severity of the exocrine pancreatic insufficiency, whereas endocrine pancreatic function is unrelated to this genotype.     

Genotyping of cystic fibrosis families with linked DNA probes

Forty-six British families, containing at least one child affected with cystic fibrosis, were typed for restriction fragment length polymorphisms (RFLPs) by the probes pmet H, pmet D, pJ3.11 and 7c22. Thirty-five (76%) were fully informative for prenatal diagnosis and carrier detection, while in the remainder prenatal exclusion of an affected fetus could be carried out in half the pregnancies. The frequencies of individual alleles did not differ between cystic fibrosis and normal chromosomes. However, the previously noted excess of one haplotype on chromosomes carrying the cystic fibrosis gene was confirmed.     

Complete screening of the CFTR gene in Argentine cystic fibrosis patients

In order to establish the nature and the distribution of mutations causing cystic fibrosis (CF) in 220 unrelated Argentine families, the present authors conducted an extensive molecular analysis of the CF transmembrane regulator (CFTR) gene. First, a direct mutation analysis of 13 common mutations was done, enabling the detection of 319 out of 440 CF alleles (72.52%). Then an exhaustive screening of the entire coding region and the adjacent sequences of the CFTR gene was performed in all patients carrying at least one unidentified CF allele using the multiplex heteroduplex analysis assay followed by direct DNA sequencing. Thirty-nine different CF mutations, including five previously undescribed mutations (i.e. L6V, Y362X, 1353insT, 2594delGT and 2686insT) and two novel polymorphisms (i.e. 1170G/C and 3315A/C) were identified. As a result, the overall detection rate increased by up to 83.45%. Besides DeltaF508, only five mutations showed frequencies higher than 1%. In addition, a total of 49% of the mutations were rare because they were found in only one CF family. This wide spectrum of CF mutations is in agreement with the heterogeneous ethnic origin of the Argentine population. The data obtained here may have important consequences for the development of adequate strategies for the molecular diagnosis of CF in Argentina.     

Spectrum of CFTR mutations in Argentine cystic fibrosis patients

The identification of different mutations which cause cystic fibrosis (CF) in Argentine patients has been performed. Initially, 10 of the most commonly mutated loci in 228 independent chromosomes were analyzed. Each allele was detected by PCR amplification of DNA samples either directly on polyacrylamide gels, by restriction enzyme digestion and agarose gels electrophoresis, or by hybridization with allele specific oligonucleotides. The AF508 mutation was found in 57% of the alleles. The frequencies of the other CF mutations were as follows: G542X 3.9%, W1282X 3.1%, N1303K 1.7%, 1717 1-G→A 0.9%, R553X 0.4%, R1162X 0.4%, whereas G551D, AI507 and S549N were not found. This direct mutation analysis enabled the detection of 155/228 CF alleles (67%). Of the remaining 73 unidentified CF alleles, 22 were investigated for the 27 exons by DGGE and 9 rare mutations were identified. The incidence of the main CF mutations analyzed was similar to that of the South European population and markedly different from other Latin American countries. The mutation data presented here may be useful for designing DNA testing strategies for CF in Argentina.     

Month of birth is not a risk factor for narcolepsy with cataplexy in the Netherlands

The month of birth has been proposed as a risk factor for narcolepsy, suggesting a harmful influence during early development. Several authors have described an excess of births in March in those developing narcolepsy later. Analysis methods in published studies varied, but no study corrected completely for possible changes in seasonal birth pattern over time in the appropriate population. The present study describes changes in seasonal birth pattern of the entire Dutch population over a 79-year span and compared the monthly birth pattern of Dutch narcoleptics with the population data. Month and year of birth were noted for 307 patients with non-familial narcolepsy with cataplexy, born in the Netherlands between 1923 and 2001. The numbers of live births per month and per year from the entire Dutch population for the same period were used to calculate a virtual data set of expected births per month with exactly the number of cataplexy cases, but with the birth pattern of the Dutch population. Observed and expected numbers per month were compared using the chi-square test. In the 1970s the peak of births shifted from spring to autumn, confirming the need to correct for changing seasonal patterns. There was no significant difference between observed and expected birth numbers per month. An effect of birth month on the occurrence of narcolepsy with cataplexy was not found in a study of 307 cases after adjusting for changing birth patterns in the general population.     

NADH dehydrogenase in cystic fibrosis

It has been claimed that the pH profile of mitochondrial NADH dehydrogenase in cultured skin fibroblasts can be used to distinguish cystic fibrosis homozygotes, heterozygotes and normal controls. This phenomenon has been examined in more readily accessible white blood cell preparations. The relative changes of activity of white cell NADH dehydrogenase in phosphate buffer at pH 8.0,8.3 and 8.6 were too small and too random to be useful in identifying the genotype of the donor.     

Sweat electrolyte and cystic fibrosis mutation analysis allows early diagnosis in Brazilian children with clinical signs compatible with cystic fibrosis

A total of 540 individuals with clinical signs suggestive of cystic fibrosis (CF) was studied. The sweat chloride was measured and the DF508, G542X, R553X, and W1282X mutations of the CF gene were screened by polymerase chain reaction (PCR). With this approach the diagnosis of CF was confirmed in 12 children, while 7 additional cases, who are heterozygous for the DF508 mutation, have had minor clinical signs. The frequency of the DF508 allele among the 540 individuals was approximately 3%. The mean age of children diagnosed with CF was 1.81 years, which is significantly earlier than in other studies of the Brazilian population. We also demonstrated that this approach has important clinical implications for earlier and adequate treatment, which was shown to be fundamental for increasing significantly the quality of life and life expectancy. This is particularly true in countries such as Brazil where most CF cases remain undiagnosed, mainly in families of low socio-economical status. Am. J. Med. Genet. 76:288–290. © 1998 Wiley-Liss, Inc.     

Attitudes and opinions of pregnant women who are not offered cystic fibrosis carrier screening

Cystic fibrosis (CF) is the most common severe, autosomal recessive disease among Caucasians. A population-based CF carrier screening programme was implemented in Victoria, Australia, in 2006. Carrier screening for CF is currently only offered in the private health system. The aim of this study was to determine the attitudes and opinions of pregnant women in the public health system, towards screening for CF. Pregnant women were recruited in the antenatal clinics of two public hospitals, and invited to participate in the study. Results of this study were compared with previous studies where screening for CF carrier status was offered. Of the participants (n=158), the majority were aged 25–34 years old (66.1%) and were Caucasian (45.8%). Compared with those who were offered screening (reported in previous studies) participants in the current study were younger, had a lower level of education and a lower income. Knowledge was significantly lower in those who were not offered screening compared with those who were offered screening. The majority of participants believe CF carrier screening should be offered in the public health system (80.5%) and almost half would have liked to receive an offer of screening during their current pregnancy (49.7%). In order for the programme to be equitable, screening for CF carrier status needs to be offered in both the public and private health system and ideally should be at no cost to the user.     

Analysis of 40 known cystic fibrosis mutations in South African patients

A total of 140 South African (SA) Caucasoid cystic fibrosis (CF) families were analysed for the common CF mutation, ΔF508. The 52 non-ΔF508 CF chromosomes in a subset of 127 of these families were also tested for 39 other known CF mutations. The most frequent mutation, apart from ΔF508 (which occurs at a frequency of 79%), was G542X (1.3%). Four other mutations, R553X, S549N, 621 + 1G→T and N1303K, were each found in single families. The other 35 mutations remained unidentified in this sample of CF families. Since 83% of SA Caucasoid CF mutations have been identified, diagnosis by mutation analysis will be possible in only 69% of CF cases. When a diagnosis has been confirmed by a positive sweat test, a combination of linked marker analysis and mutation detection will be necessary if prenatal diagnosis and carrier detection are to be offered in the remaining families.