ABSTRACT
The observation that a lot of children with Down syndrome are born to mothers with young age made it important to identify the mechanisms involved in this young age group. It was found that DNA hypomethylation is associated with chromosomal instability and abnormal chromosome segregation. This knowledge led to the clarification of the role of enzymes involving in the methylation reaction like Methylene Tetrahydrofolate Reductase enzyme [MTHFR]. The C-T common polymorphism at nucleotide 677 [C677T], which results into an alanine to valine substitution in the MTHFR protein, caused higher thermolability and reduced enzyme activity in lymphocyte extracts. In order to verify this association, we studied the presence of the C677T polymorphism of the MTHFR gene in 50 mothers of Down syndrome children and 50 control mothers. A non-significant higher incidence of the mutant T allele in Down syndrome children mothers [6%] than in control [2%] was detected. These results do not support the presence of an increased risk of Down syndrome mothers carriers of the T allele in Egyptian population