Methionine synthase A2756G and reduced folate carrier1 A80G gene polymorphisms as maternal risk factors for Down syndrome in Egypt

Background: Polymorphisms of genes encoding enzymes involved in folate metabolism have long been hypothesized to be maternal risk factors for Down syndrome, however, results are conflicting and inconclusive

Aim of the study: To analyze the effect of methionine synthase [MTR] A2756G, and reduced folate carrier [RFC1] A80G gene polymorphisms on the maternal risk for DS

Patients: This study was conducted in the Medical Genetics Center, Ain-Shams University hospitals, on a total of 170 mothers of children, diagnosed with Down syndrome, who were attending the center. Eighty-five control mothers were also enrolled in the study

Methods: Genotype analyses were performed using PCR-RFLP to detect RFC1A80G and MTRA2756G gene polymorphisms in all case and control mothers

Results: Comparing RFC1A80G genotype frequency between both groups revealed, that the frequency of the AA genotype in case mothers [94.11%] is highly significantly [p< 0.001] greater than its frequency in control mothers [74.11%], with no significant difference between the two groups regarding GG genotype. Comparing RFC1 A80G allele frequency between the two groups revealed a high frequency of the A allele among case mothers [94.11%], which showed a highly statistically significant difference [p<0.001] from the control group [55.29%], meanwhile the G allele showed a low frequency of 5.88% in DS mothers compared to 22.35% in the control mothers, with a highly statistically significant difference [p<0.001] between the two groups. Regarding MTRA2756G polymorphism, it was found that the AA genotype predominated in the control group [65.88%] with a highly statistically significant difference [p< 0.001] from case mothers group [5.88%]. Comparing MTR allele frequency between the two groups revealed predominance of the G allele among mothers of DS children [76.47%]

Conclusion: Current results provide strong evidence that the MTRA2756G, and RFC1 80 A genotypes could be considered as maternal risk factors for DS in Egyptian mothers

Association of dopamine D4 receptor gene variants with autism.

Background: Autism spectrum disorder (ASD) is a heritable neurodevelopmental disorder with poorly understood and complex etiology. The central dopaminergic system is strongly implicated in ASD pathogenesis. Genes encoding various elements of this system have been linked to ASD. This study aimed to estimate the distribution frequency of dopamine D4 receptor-exon III repeat region polymorphic genotypes among Egyptian children with autism. Methods: This case-control study included 178 children with autism (mean age 4.46±1.72 years) (118 males and 60 females) and a normal control group (n=128) of matching age and gender. Assessments by DSMIV- TR criteria, Stanford-Binet intelligence scale and childhood autism rating scale (CARS) were done. Assay for DRD4 48 bp VNTR genotypes was performed on amplified DNA by RFLP-PCR. Results: The 4/4 allele had the highest frequency among both autistic (39.32%) and control children (62.5%), with no significant difference between them. The 7/7 allele had also a high frequency (33.7%) among autistic patients, which was significantly different (p˂0.05) from the control group (12.5%) Furthermore, 70% of the patients carrying the 7/7 allele had the lowest IQ scores (58.5±6.5). Conclusions: There is a strong evidence that the DRD4 7/7 allele might be a risk factor for autism.