Teratogen update: paternal exposures-reproductive risks

Birth prevalence and pattern of osteochondrodysplasias in an inbred high risk population

BACKGROUND

Define the pattern and birth prevalence of the different types of osteochondrodysplasias in newborn infants in the United Arab Emirates (UAE) population, which is highly inbred and where termination of pregnancy is not accepted.

METHODS

All infants with a birth weight of 500 gm and above in the three hospitals in Al Ain Medical District of the UAE were studied prospectively over a period of 5 years. For each live birth or stillbirth with suspected skeletal dysplasia, a detailed clinical and radiological examination was carried out. Pregnancy history and information regarding parental age, ethnic origin, family history, and level of consanguinity were obtained and a pedigree was constructed.

RESULTS

Among the 38,048 births during the study period, 36 (9.46/10,000 births) had some type of skeletal dysplasia. Eighteen cases were attributed to autosomal recessive genes (4.7/10,000 births), 10 were due to apparent new dominant mutations (2.62/10,000), five were autosomal dominant type (1.3/10,000) and one was X-linked dominant type (0.26/10,000). In three cases, inheritance was unknown. The most common recessive type of skeletal dysplasia in our series was fibrochondrogenesis (1.05/10,000), followed by chondrodysplasia punctata (0.78/10,000). The birth prevalence rate of skeletal dysplasia doubled in the last 2 years of the 5-year observation period (6.74/10,000 in 1996 vs. 12.86/10,000 in 1999, and 13.45/10,000 in 2000). This increase involved cases caused by new dominant mutations, and occurred mainly in the first half of 1999.

CONCLUSION

This prospective study has identified a high birth prevalence of skeletal dysplasia, and risk factors are postulated. These findings represent an accurate birthprevalence figure and a useful baseline for this group of birth defects in the UAE.

Childhood acute lymphoblastic leukemia associated with parental alcohol consumption and polymorphisms of carcinogen-metabolizing genes

BACKGROUND

Limited information is available on the association of parental consumption of alcohol prior to and during pregnancy with the risk of childhood leukemia, as well as for the potentially modifying role of genetic polymorphisms.

METHODS

We conducted a population-based, case-control study of 491 incident cases of acute lymphoblastic leukemia age 0-9 years and matched on age and sex to 491 healthy controls. Cases were identified at tertiary care centers in the Province of Québec between 1980 and 1993. Each parent was interviewed separately about alcohol consumption habits. We also used a case-only design with 186 cases to estimate interaction odds ratios between prenatal exposure and child DNA variants in the GSTM1 and CYP2E1 genes.

RESULTS

The adjusted odds ratio for any maternal consumption during pregnancy was 0.7 (95% confidence interval = 0.5-0.9). The interaction odds ratios for the GSTM1 null genotype during third pregnancy trimester was 2.4 (95% confidence interval = 1.1-5.4); the interaction odds ratio for CYP2E1 variant G-1295C (or allele *5) during the nursing period was 4.9 (95% confidence interval = 1.5-16.7).

CONCLUSIONS

The observed association with maternal alcohol consumption during pregnancy could be due to the potential chemopreventive effects of flavonoids found in wine and beer. These possible effects of alcohol may be at least partially genetically determined, although data are preliminary.

Chronic cyclophosphamide treatment alters the expression of stress response genes in rat male germ cells

Increases in the survival rate of men treated with chemotherapeutic drugs and their desire to have children precipitate concerns about the effects of these drugs on germ cells. Azoospermia, oligospermia, and infertility are common outcomes resulting from treatment with cyclophosphamide, an alkylating agent. Exposure of male rats to cyclophosphamide results in dose-dependent and time-specific adverse effects on progeny outcome. Elucidation of the effects of chronic low-dose cyclophosphamide treatment on the expression of stress response genes in male germ cells may provide insight into the mechanisms underlying such adverse effects. Male rats were gavaged with saline or cyclophosphamide (6 mg/kg) for 4-5 wk; pachytene spermatocytes, round spermatids, and elongating spermatids were isolated; RNA was extracted and probed on cDNA arrays containing 216 cDNAs. After saline treatment, 125 stress response genes were expressed in pachytene spermatocytes (57% of genes studied), 122 in round spermatids (56%), and 83 in elongating spermatids (38%). Cyclophosphamide treatment reduced the number of genes detected in all germ cell types. The predominant effect of chronic cyclophosphamide exposure was to decrease the expression level of genes in pachytene spermatocytes (34% of genes studied), round spermatids (29%), and elongating spermatids (4%). In elongating spermatids only, drug treatment increased the expression of 8% of the genes studied. The expression profiles of genes involved in DNA repair, posttranslational modification, and antioxidant defense in male germ cells were altered by chronic cyclophosphamide treatment. We hypothesize that the effects of cyclophosphamide exposure on germ cell gene expression during spermatogenesis may have adverse consequences on male fertility and progeny outcome.