Down syndrome(ds) is the most common chromosomal abnormality.the most important factor in ds is increased maternal age so after the age of 35,the risk of ds in pregnancy increases. nondisjunction in cell divisions is the main cause of the ds. apolipoprotein e is a 317 amino acid glycoprotein that plays an essential role in metabolism and cholesterol transport. alzheimer's disease(ad) is one of the symptoms of adults with ds.the apoe allele e4 has been identified as a risk factor for ad and also, plays a main role in nondisjunction. an increased risk of ad in mothers of adults with ds has been reported. we hypothesized that young mothers of ds children (<35 age)could have an increased frequency of apoe allele e4 so we studied apoe allele distribution in cases of trisomy 21and their parents. in present study we investigated association of 112 codon of apoe gene c/t and 158 codon of apoe gene c/t with ds children and their parents in iran.
In this case-control study, 33 ds children and their parents were matched for age with 90 families without any history of ds. genotyping was performed by arms-pcr technique.statistical analysis was performed by spss v.21 software.
It indicated that there is a significant difference in allele distribution between case and control groups. the c allele for 112 codon of apoe gene and the t allele for 158 codon of apoe gene may associate with nondisjunction.e4 allele frequency in mothers of ds is about %16 more than those in control group.
According to the results of this study the t allele in 158 codon of apoe gene and the c allele in 112 codon of apoe gene could be considered as susceptibility genetic factors for nondisjunction.