Hair Genetics : A Study Of Dna Sequence Variations Essay
A study of DNA sequence variations in melanocortin-1-receptors or MC1R genes found many variants of amino acid found in people who were red-haired but rarely found in the non-red people. Researchers have identified 3 common amino-acid-polymorphisms associated commonly with red haired people viz., R160W, R151C, & D294H. The abbreviated names mean common amino acid types were found in positions 160 151, & 294 in proteins are arginine (R), cysteine (C), arginine & aspartic acid (D), while amino acids histidine (H) & tryptophan (W), were found in the redheads (Catherine A Guenther, 2016).
Many rare polymorphisms of amino acid are there in MC1R genes, some may be linked to red hair. Surveys of genetic variations in genomes of big cross-sections of Icelanders found MC1R as one gene having strong links to red hair. However, knowledge of genotypes of individuals at a MC1R locus is insufficient for predicting if they will have red hair. It was found only 74% individuals homozygous for amino-acid tryptophan at the 160 position get red hair, and 4% heterozygous for tryptophan get red hair. It was also found that 5-pairs of twins who were dizygotic with identical genotypes for MC1R, had red hair for one twin while the other did not.
Variety in hair colors has made summarizing results of different detailed family studies difficult. Davenport & Davenport (1909) had reported many examples of 2 brown-hair parents with red-hair offspring’s which…