Centromere reference models for human chromosomes X and Y satellite arrays

Area of Science:

• Genomics
• Molecular Biology
• Human Genetics

Background:

• The human genome sequence is incomplete, particularly in centromeric and heterochromatic regions.
• These regions are crucial for centromere function, chromosome pairing, and segregation during cell division.
• Satellite DNAs, characterized by long arrays of tandem repeats, pose assembly challenges due to sequence homogeneity.

Purpose of the Study:

• To model and characterize human centromeric satellite DNA arrays on chromosomes X and Y.
• To assess sequence variation within these arrays across diverse human populations.
• To establish a foundation for sequencing repeat-rich genomic regions.

Main Methods:

• Utilized whole-genome shotgun reads for monomer sequence and ordering information.
• Modeled two haploid human satellite arrays on chromosomes X and Y.
• Evaluated short-read mappability and chromosome specificity of array sites.
• Assessed sequence variation across 366 individuals from distinct human populations.

Main Results:

• Achieved initial characterization of 3.83 Mb of centromeric DNA.
• Identified two satellite array variants in both X and Y centromeres based on length and sequence composition.
• Demonstrated concerted evolution of satellite DNAs.

Conclusions:

• Provides the first sequence characterization of a regional centromere.
• Establishes a methodology for characterizing complex, repeat-rich genomic regions.
• Enables future genomic studies of previously inaccessible heterochromatic regions.