X-chromosomal STR based genetic polymorphisms and demographic history of Sri Lankan ethnicities and their relationship with global populations

Nandika Perera,Gayani Galhena,Gaya Ranawaka

doi:10.1038/s41598-021-92314-9

Nandika Perera, Gayani Galhena + Show 1 more

Open Access

https://doi.org/10.1038/s41598-021-92314-9

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Abstract

A new 16 X-short tandem repeat (STR) multiplex PCR system has recently been developed for Sr Lankans, though its applicability in evolutionary genetics and forensic investigations has not been thoroughly assessed. In this study, 838 unrelated individuals covering all four major ethnic groups (Sinhalese, Sri Lankan Tamils, Indian Tamils and Moors) in Sri Lanka were successfully genotyped using this new multiplex system. The results indicated a high forensic efficiency for the tested loci in all four ethnicities confirming its suitability for forensic applications of Sri Lankans. Allele frequency distribution of Indian Tamils showed subtle but statistically significant differences from those of Sinhalese and Moors, in contrast to frequency distributions previously reported for autosomal STR alleles. This suggest a sex biased demographic history among Sri Lankans requiring a separate X-STR allele frequency database for Indian Tamils. Substantial differences observed in the patterns of LD among the four groups demand the use of a separate haplotype frequency databases for each individual ethnicity. When analysed together with other 14 world populations, all Sri Lankan ethnicities except Indian Tamils clustered closely with populations from Indian Bhil tribe, Bangladesh and Europe reflecting their shared Indo-Aryan ancestry.

Highlights

A new 16 X-short tandem repeat (STR) multiplex PCR system has recently been developed for Sr Lankans, though its applicability in evolutionary genetics and forensic investigations has not been thoroughly assessed
We report for the first time, the X chromosome STRs (X-STRs) based population genetic information of all four main ethnicities in Sri Lanka
The 16 X-STR assay system used in the current study is highly polymorphic and exhibited high forensic efficiency for all four ethnicities tested indicating its suitability to be used in both evolutionary genetic analysis and forensic applications of Sri Lankans

Summary

Introduction

A new 16 X-short tandem repeat (STR) multiplex PCR system has recently been developed for Sr Lankans, though its applicability in evolutionary genetics and forensic investigations has not been thoroughly assessed. The Bengali prince Vijaya and his seven hundred followers, who are descendants from the Indo-Aryans natives of the northern Indian subcontinent laid the foundation to the Sinhalese in 543 BCE4 They vanquished the aboriginal Veddas and converted Sri Lanka to a Sinhalese territory until the Dravidian rulers from South India invaded the northern part of the island in the fifth century A D4. The group known as Moors comprise 9.2%1 (1.86 million) of the Sri Lankan population and maintain unique sociocultural features which are based largely on the Islamic faith They speak a Dravidian language that contains large number of Arabic words that is generally referred to as ‘‘Arabic Tamil’’5. Comprising a relative minority of 0.84 million people (4.2% of the total population)[1], Indian Tamils are confined to the central hills in Sri Lanka with a relatively low admixture with other ethnic groups due to socio cultural reasons associated with their more recent immigrant status

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