Application of victims' fingernails in Forensic DNA analysis.

DNA extracted from the victims’ fingernails may assist in the identification of the aggressor. Fingernails were collected from 8 victims, and were subjected to DNA extraction using the Kit « Tissue and Hair Extraction Kit (Promega) ». All samples were typed for 15 autosomal short tandem repeats and for amelogenin using the Kit « Powerplex TM16 system (Promega) » and the ABI Prism 310 DNA sequencer. The profiles obtained were compared with those achieved by similar typing of victims’ and suspects’ blood. In two Forensic investigations, mixed genotypes were detected in DNA extracted from the nails: Alleles originating from the victim were coamplified with other alleles that matched the suspect’s genotypic profile. This indicated that victims’ fingernails contained biological material (blood, epithelial cells) originating from the suspect. Our results confirmed the usefulness of the nails as a specimen for forensic identification of the aggressor.

MTHFR Gene variants C677T, A1298C and association with Down syndrome: A Case-control study from South India.

BACKGROUND: The 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphisms and low folate levels are associated with inhibition of DNA methyltransferase and consequently DNA hypomethylation. The expanding spectrum of common conditions linked with MTHFR polymorphisms includes certain adverse birth outcome, pregnancy complications, cancers, adult cardiovascular diseases and psychiatric disorders, with several of these associations remaining still controversial. Trisomy 21 or Down syndrome (DS) is the most common genetic cause of mental retardation. It stems predominantly from the failure of chromosome 21 to segregate normally during meiosis. Despite substantial research, the molecular mechanisms underlying non-disjunction leading to trisomy 21 are poorly understood. MATERIALS AND METHODS: Two common variants C677T and A1298C of the MTHFR gene were screened in 36 parents with DS children and 60 healthy couples from Tamil Nadu and Karnataka. The MTHFR genotypes were studied by RFLP analysis of PCR-amplified products and confirmed by sequencing. RESULTS: The CT genotype was seen in three each (8.3%) of case mothers and fathers. One case father showed TT genotype. All the control individuals exhibited the wild type CC genotype. A similar frequency for the uncommon allele C of the second polymorphism was recorded in case mothers (0.35) and fathers (0.37) in comparison with the control mothers (0.39) and fathers (0.37). CONCLUSION: This first report on MTHFR C677T and A1298C polymorphisms in trisomy 21 parents from south Indian population revealed that MTHFR 677CT polymorphism was associated with a risk for Down syndrome.