Sequence variation in ZFX introns in human populations

Area of Science:

• Human Genetics
• Population Genetics
• Molecular Evolution

Background:

• Understanding human DNA variation is crucial for tracing population history and migration.
• Nuclear DNA, unlike Y-linked DNA, provides insights into broader ancestral patterns.

Purpose of the Study:

• To investigate DNA variation within the ZFX gene across diverse human populations.
• To estimate the age of the most recent common ancestor (T) using nuclear DNA sequences.

Main Methods:

• Sequencing of the last intron of the ZFX gene (approximately 1,151 bp) from 29 individuals worldwide.
• Analysis of a single polymorphic site within an Alu sequence in the ZFX gene intron.
• Estimation of the age of the most recent common ancestor (T) based on sequence data.

Main Results:

• A single polymorphic site was identified in the ZFX gene's last intron, present at intermediate frequencies globally.
• Human nucleotide diversity in this nuclear DNA region was found to be very low (0.04%).
• The estimated age of the most recent common ancestor (T) was approximately 306,000 years, with a 95% confidence interval of 162,000–952,000 years.

Conclusions:

• The ZFX gene shows low nucleotide variation in human populations, supporting the notion of limited overall nuclear DNA diversity.
• The estimated age of the most recent common ancestor from ZFX gene data is significantly older than estimates derived from Y-linked sequences.
• The observed ZFX polymorphism may represent a shared ancestral polymorphism or recent migration across continents.