Common gene variants for skin tone found:

Common gene variants for skin tone found:

Context

• A study of nearly 300 people living in different parts of India found that nine single-base variants (single-nucleotide polymorphisms or SNPs) account for 31% variation in the color of the skin.

What are single-nucleotide polymorphisms?

• Single nucleotide polymorphisms, frequently called SNPs (pronounced “snips”), are the most common type of genetic variation among people.
• Each SNP represents a difference in a single DNA building block, called a nucleotide.
• SNPs occur normally once in every 300 nucleotides on average, which means there are roughly 10 million SNPs in the human genome.

What was the observation of the study?

• Researchers at the Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad tested 30 SNPs
• The single-base variant rs1426654 accounts for 25-38% of skin colour variation between Africans and Europeans.
• Rs1426654 was one of the four SNPs that had maximum effect on skin pigmentation in people living here.

What is the reason behind diverse skin pigmentation?

• The gene variants (allele) that give the skin a darker color due to the presence of higher amount of melanin pigment are found in people living in south India
• Being closer to the equator, the darker skin in the south Indian population protects them from strong UV rays of the Sun.
• The darker skin of people in south India was reflected in higher mean melanin index (a representation of the amount of melanin in the skin) of 48 compared with mean melanin index of 39 in the case of people in north India.
• The population in east and west India has intermediate values (mean MI of 41). The melanin index did not vary within a given geographical region.