Human monogenic disease genes have frequently functionally redundant paralogs

Area of Science:

• Genetics
• Molecular Biology
• Evolutionary Biology

Background:

• Mendelian disorders arise from gene mutations causing functional impairments.
• Gene duplication is a significant evolutionary mechanism.
• The role of gene duplicates in masking disease-causing mutations is not fully understood.

Purpose of the Study:

• To investigate the extent to which gene duplicates functionally compensate for genes responsible for monogenic diseases (MDs).
• To explore the evolutionary implications of functional redundancy in disease genes.

Main Methods:

• Comparative analysis of human disease genes and their duplicates.
• Assessment of functional similarity between duplicated disease genes and their paralogs.
• Examination of evolutionary pressures (purification selection) on duplicated disease genes.

Main Results:

• Human genetic disorder genes are significantly enriched in duplicates compared to non-disease genes.
• Duplicated disease genes exhibit higher functional similarity with their closest paralogs than duplicated non-disease genes of comparable age.
• Evidence suggests functional compensation by duplicates masks deleterious mutations, reducing their purging from the population.

Conclusions:

• Gene duplication provides functional redundancy that can mask the phenotypic effects of mutations causing monogenic disorders.
• This compensation mechanism contributes to the propagation of defective genes within populations.
• Expression stochasticity of duplicate genes may lead to disease manifestation in subpopulations, explaining the persistence of genetic disorders.