Integrated analyses reveal unexpected complex inversion and recombination in RH genes.

Area of Science:

• Genetics
• Immunology
• Molecular Biology

Background:

• The D-- phenotype is associated with severe hemolytic transfusion reactions and hemolytic disease of the fetus and newborn.
• Defects in the RHCE gene are the typical cause of the D-- phenotype.

Purpose of the Study:

• To investigate the genetic basis of the D-- phenotype in a proband and their family.
• To identify the underlying cause of absent RhCE protein expression despite intact RHCE exons.

Main Methods:

• Phenotypic analysis and Sanger sequencing.
• Whole-genome sequencing using Oxford Nanopore Technologies.
• Comprehensive analysis including Pacific Biosciences long-read target sequencing, Bionano optical genome mapping, and targeted next-generation sequencing.

Main Results:

• Inconsistent results between phenotypic analysis and Sanger sequencing in the D-- proband.
• Whole-genome sequencing revealed inversion and copy number variation loss in the RHCE gene region.
• Identification of two novel recombinant RHCE haplotypes (RHCE∗Ce(1-2)-D(3-10) and RHCE∗Ce(1-2)-D(3-10)-Ce(10-8)-Ce(3-10)) with identified breakpoints.

Conclusions:

• Discovery of hereditary large inversion and recombination events between RHD and RHCE genes causing lack of RhCE expression.
• Highlights the utility of integrated genetic analyses for complex genetic disorders.
• Provides new insights into RH genotyping and the genetic basis of the D-- phenotype.