Familial aggregation of albuminuria and arterial hypertension in an Aboriginal Australian community and the contribution of variants in <Emphasis Type="Italic">ACE</Emphasis> and <Emphasis Type="Italic">TP53</Emphasis>

Background

Aboriginal Australians are at high risk of cardiovascular, metabolic and renal diseases, resulting in a marked reduction in life expectancy when compared to the rest of the Australian population. This is partly due to recognized environmental and lifestyle risk factors, but a contribution of genetic susceptibility is also likely.

Methods

Using results from a comprehensive survey of one community (N?=?1350 examined individuals), we have tested for familial aggregation of plasma glucose, arterial blood pressure, albuminuria (measured as urinary albumin to creatinine ratio, UACR) and estimated glomerular filtration rate (eGFR), and quantified the contribution of variation at four candidate genes (ACE; TP53; ENOS3; MTHFR).

Results

In the subsample of 357 individuals with complete genotype and phenotype data we showed that both UACR (h²?=?64%) and blood pressure (sBP h²?=?29%, dBP, h²?=?11%) were significantly heritable. The ACE insertion-deletion (P?=?0.0009) and TP53 codon72 polymorphisms (P?=?0.003) together contributed approximately 15% of the total heritability of UACR, with an effect of ACE genotype on BP also clearly evident.

Conclusions

While the effects of the ACE insertion-deletion on risk of renal disease (especially in the setting of diabetes) are well recognized, this is only the second study to implicate p53 genotype as a risk factor for albuminuria - the other being an earlier study we performed in a different Aboriginal community (McDonald et al., J Am Soc Nephrol 13: 677-83, 2002). We conclude that there are significant genetic contributions to the high prevalence of chronic diseases observed in this population.

     

Cytogenetics of childhood T-cell leukemia

The karyotypes of 57 cases of childhood T-cell acute lymphoblastic leukemia (ALL) were analyzed to establish the cytogenetic profile in this disease. Three questions were of particular interest. Do the chromosomal changes in T-cell ALL preferentially affect bands where genes encoding the T-cell receptor for antigen (TCR) have been mapped? Do alterations involving the TCR gene regions appear with any notable frequency in B-progenitor ALL? Do chromosomal abnormalities in this disease relate to stage of T-cell ontogeny? A relatively high proportion of cases (65%) had a pseudodiploid karyotype at presentation, the majority (58%) characterized by a translocation. The overall frequency of translocations was 44%, comparable to that among all banded cases of ALL seen in our laboratory. Hypodiploidy and hyperdiploidy were exceedingly rare (only four of 57 cases); 16 cases (28%) had apparently normal karyotypes. In half the cases with a translocation (14 of 24), the breakpoints were in regions to which the alpha and beta chain TCR genes have been mapped. Chromosomal breakpoints that were consistently observed in the vicinity of TCR gene loci were 7q32-q36 (TCR beta chain; n = 8), 14q11-q13 (TCR alpha chain; n = 6); other frequent breakpoints were 9p13-pter (n = 8) and 6q15-qter (n = 9). Chromosomal alterations occurred near TCR gene loci significantly more often in T-cell cases than in a comparison group of 335 patients with B-cell precursor ALL (26% v 1.5%, P = .0001). Stage I thymocyte development (CD7+, CD2+, CD5+, CD1-, CD3-, CD4-, CD8-) was noted in 23 cases, stage II (CD7+, CD2+, CD5+, CD1+, CD3-, CD4 +/-, CD8 +/-) in 25 cases, and stage III (CD9+, CD2+, CD1-, CD5+, CD3+, and either CD4+ or CD8+) in nine cases. The only statistically significant associations between cytogenetic findings and T-cell ontogeny were a higher frequency of normal karyotypes in cases with stage I thymocytes, and of pseudodiploidy in stage II cases. There was no apparent relationship between particular translocations and level of thymocyte maturation. Our findings indicate that most children with T-cell ALL have pseudodiploid karyotypes, although a surprisingly high percentage lack demonstrable abnormal clones. Specific chromosomal changes do not appear to be related to discrete stages of T-cell ontogeny as defined in this study, but they occur preferentially in bands containing TCR genes.     

Prognostic importance of structural chromosomal abnormalities in children with hyperdiploid (greater than 50 chromosomes) acute lymphoblastic leukemia

Approximately one fourth of children with newly diagnosed acute lymphoblastic leukemia (ALL) have hyperdiploid (greater than 50 chromosomes) blasts and a relatively favorable prognosis. Nonetheless, a substantial proportion of these patients fail therapy. We studied 138 children (70 male, 68 female) with hyperdiploid greater than 50 ALL to assess initial clinical and cytogenetic features that might predict treatment failure. In 85 of these cases (62%), structural chromosomal abnormalities were also present; clinical and laboratory features in this group did not differ from those of the 53 cases with only numeric abnormalities. However, of the 28 failures seen at a median follow-up of 4 years, 22 occurred in cases with structural chromosomal abnormalities (P = .03 by Breslow test). In a multivariate analysis, only the presence of structural chromosomal abnormalities and male gender were independently associated with treatment failure. Structural chromosomal abnormalities in cases of ALL with greater than 50 chromosomes may define a biologically different form of leukemia characterized by increased likelihood of drug resistance.     

Nonrandom involvement of the 12p12 breakpoint in chromosome abnormalities of childhood acute lymphoblastic leukemia

We studied the presenting clinical and biologic features of 23 children with acute lymphoblastic leukemia (ALL) whose leukemic marrow karyotypes contained abnormalities involving the short arm of chromosome 12. Nineteen of the abnormalities were assigned to the 12p12 breakpoint. The median age of the children was 5 years (range 2 to 13 years) and their initial leukocyte counts ranged from 1,800 to 424,000/microL (median 30,000/microL). Twenty-one patients (91%) had common phenotype ALL (CALLA+, HLA-DR+), including three cases with a pre-B cell phenotype (CIg+). The remaining two cases were T cell in origin. The French-American-British (FAB) morphologic type of lymphoblastic leukemia was L1 in all cases but one. With a median follow-up of 11 months, four patients have relapsed and another failed induction therapy. The modal chromosome number in all cases was less than 50. Three distinct cytogenetic patterns, with apparently similar clinical manifestations, were noted: terminal deletions of chromosome 12 in 10 cases, apparently balanced reciprocal translocations in 6, and unbalanced translocations in 7. All translocations were between the 12p arm and different donor chromosomes except for chromosomes 7, 9, and 17, which participated twice. Only two patients had identical translocations: t(7;12)(q11;p12). This unusual variation in donor chromosomes and breakpoints suggests that translocations involving the 12p are specific with respect to only one member of the translocation pair, namely chromosome 12. The relatively high frequency of the 12p abnormalities in this study (10% of all completely banded cases seen over a 35-month period) warrants further investigation.     

EFFECT OF SUBCLINICAL LEAD INTOXICATION ON LARYNGEAL CANCER

SUMMARY In this study we investigated the possible relationship of laryngeal cancer and subclinical lead intoxication, using the depression of aminolevulinic acid dehydratase (ALAD) activity in blood as indicator. Twenty-six patients with laryngeal cancer and 53 normal controls met the criteria to enter the study. Blood ALAD activity values in the patients with laryngeal cancer ranged from 27.1 to 75.3 U/l with a mean of 50.79 U/l. The respective values in the control group ranged from 36.2 to 98 U/l with a mean of 59.76 U/l. There was a statistically significant difference between the two means (0.001 <p<0.01), whereas blood lead concentrations in all patients were within normal limits. These findings support the hypothesis that low level lead intoxication (subclinical blood lead levels), from cars, industries and products, may contribute to the risk of laryngeal cancer. Further investigation is needed to clarify the exact relationship between lead and cancer of the larynx.     

Cellular infiltration and cytokine mRNA expression in perennial allergic rhinitis

BACKGROUND: Allergen challenge in allergic rhinitis patients leads to local eosinophilia and Th2-type cytokine expression. Natural exposure to grass pollen is additionally characterized by epithelial mast-cell infiltration. We hypothesized that perennial allergic rhinitis is also associated with T-cell and eosinophil infiltration of the nasal mucosa, local Th2-type cytokine expression, and increased numbers of nasal epithelial mast cells. METHODS: Nasal biopsies from perennial allergic rhinitis patients and controls were analysed by immunocytochemistry for different cell populations and in situ hybridization for cytokine mRNA-expressing cells. RESULTS: Perennial allergic rhinitis was associated with increased numbers of submucosal CD3+ T cells (P=0.05), EG2+ activated eosinophils (P=0.01), and CD68+ macrophages (P=0.01) compared to controls. Epithelial, but not submucosal, tryptase-positive mast cells were also elevated in rhinitics compared to controls (P=0.01). The numbers of cells expressing interleukin (IL)-5 were higher (P=0.01) and the numbers of cells expressing IL-2 were lower (P=0.04) in rhinitic patients than controls. There were no significant differences for either IL-4 or interferon-gamma between the groups. CONCLUSIONS: Perennial allergic rhinitis is characterized by mast-cell migration into the epithelium; submucosal infiltration by T cells, eosinophils, and macrophages; and an imbalance in local T-cell cytokine production in favour of enhanced IL-5 and reduced IL-2 expression.     

Management of mandibular fractures

Background: To evaluate the cases of mandibular fractures treated by open reduction and rigid fixation at the Armed Forces Medical College, Pune.