Maternal risk factors in young Egyptian mothers of Down syndrome
Introduction: We investigated the possible maternal risk factors that may
increase the incidence of Down syndrome (DS) in young Egyptian mothers
(younger than 35 years) especially methylene tetrahydrofolate reductase
(MTHFR) enzyme C677T polymorphism.
Subjects and Methods: The study included 200 mothers of karyotypically
ascertained non-disjunction DS attending Genetics clinic, Children’s hospital, Ain Shams University (100 mothers were < 35 years and 100 mothers ≥ 35 years). 50 mothers of none-DS children served as a control group. For all cases, history was taken laying stress on: Parental ages at conception, maternal grandparent’s ages at conception of mother, DS birth order, history of oral contraceptive use 6 months before conception, genital infection, vitamin supplementation and smoking or exposure to irradiation.
Results: MTHFR C677T mutational analysis was done to twenty DS mothers
with ages ≤ 35 years revealed that 35% of young mothers had C677T mutation (10% had homozygous mutation and 25% had heterozygous mutation). MTHFR C677T polymorphism was found to be a possible maternal genetic risk factor for DS although statistically non-significant.
Other maternal risk factors included the use of oral contraceptive pills (OCP) 6 months before pregnancy which was significantly higher only in DS
mothers ≥ 35 years. on the other hand, parental consanguinity, maternal grandparents’ ages, the presence of genital infection and birth order did not show a significant difference between young and old mothers of DS.
Conclusion: MTHFR C677T could not be considered as a maternal risk factor in young Egyptian mothers of DS. The risk effect may depend on gene-environment interaction between the genotype and dietary intake in particular folic acid consumption which should be further studied on a larger scale population including other MTHFR polymorphisms and environmental factors. Other risk factors may include the use of OCP in older mothers. Parents consanguinity, paternal age and maternal grandparents’ ages were not found to be risk factors in DS in this study.
Keywords: Down syndrome, risk factors, mothers, MTHFR.