Y-STR diversity in the Himalayas.

Area of Science:

• Population genetics
• Human evolutionary studies
• Forensic genetics

Background:

• The Himalayas are a region of significant linguistic and ethnic diversity, suggesting a crucial role in shaping regional genetic landscapes.
• Previous Y-chromosome studies indicated the Himalayas act as a barrier to gene flow across the mountain range.

Purpose of the Study:

• To analyze Y-chromosomal short tandem repeat (Y-STR) diversity in Nepalese (Tamang, Newar, Kathmandu) and Tibetan populations.
• To investigate patterns of gene flow and genetic differentiation within the Himalayan region.

Main Methods:

• Analysis of 17 Y-STR loci using the AmpFlSTR® Yfiler kit in 344 unrelated males.
• Haplotype diversity calculations and phylogenetic analyses.
• Median-joining network construction for haplogroup O3a3c-M134.

Main Results:

• High haplotype diversity was observed across all four populations, with Tibet showing the highest (0.9990) and Tamang the lowest (0.9545).
• No shared Y-STR profiles were found among the populations, indicating a lack of recent gene flow.
• Phylogenetic analyses suggest genetic influence from India in Kathmandu and Newar populations, while Tamang and Tibet show limited gene flow from the subcontinent.
• Reduced Y-STR diversity in the Tamang population may indicate a founder effect or a recent bottleneck event.

Conclusions:

• The genetic uniqueness of these four Himalayan populations supports the need for separate population databases for forensic and genetic studies.
• The findings highlight the complex genetic history shaped by geographical barriers and historical migration patterns in the Himalayas.