Loss-of-function mutations in the EGF-CFC gene CFC1 are associated with human left-right laterality defects

Area of Science:

• Developmental Biology
• Genetics
• Human Physiology

Background:

• Vertebrates exhibit consistent left-right (L-R) asymmetry of internal organs.
• L-R axis defects (heterotaxy) affect 1 in 8,500 human births, with limited known genetic causes.
• EGF-CFC genes, like mouse Cfc1 and zebrafish oep, are crucial for L-R axis formation in model organisms, acting as co-factors for Nodal signaling.

Purpose of the Study:

• To investigate the role of human CFC1 (encoding CRYPTIC protein) in human heterotaxy.
• To determine if loss-of-function mutations in CFC1 cause L-R axis defects in humans.
• To assess the functional consequence of identified CFC1 mutations.

Main Methods:

• Identified loss-of-function mutations in human CFC1 in patients with heterotaxy.
• Analyzed cellular localization of mutant CRYPTIC proteins in transfected cells.
• Assessed functional defects using a zebrafish oep-mutant rescue assay.

Main Results:

• Identified loss-of-function mutations in human CFC1 in patients with heterotaxy.
• Mutant CRYPTIC proteins showed aberrant cellular localization.
• Mutant proteins were functionally defective in a zebrafish rescue assay, confirming impaired L-R axis formation.

Conclusions:

• Human CFC1 mutations are a cause of heterotaxy, demonstrating the essential role of CRYPTIC protein in L-R axis determination.
• The function of EGF-CFC genes in L-R axis formation is conserved from fish to humans.
• Genetic or environmental modifiers may influence the final phenotype in human heterotaxy patients.