Disorder in re-methylation process of homocysteine to methionine due to mutation in betaine homocysteine methyltransferase enzyme (BHMT) coding gene, leads to decrease in S-adenosyl methionine (SAM) synthesis which takes part in DNA methylation as a methyl donor. As a result, it can promote hypo-methylation of DNA, chromosome instability, and chromosome missegregation, which in turn is one of t...

down syndrome is one of the most common causes of mental retardation observed in approximately 1/700 live birth. the use of two or more str markers related to chromosome 21 facilitates the diagnosis of down syndrome within about six hours from the collection of the samples. this is the first study has been performed in iranian population to assess the diagnostic value of using small tandem repe...