Submicroscopic deletions at 13q32.1 cause congenital microcoria

Area of Science:

• Genetics
• Ophthalmology
• Molecular Biology

Background:

• Congenital microcoria (MCOR) is a rare autosomal-dominant disorder.
• It is characterized by the iris's inability to dilate due to the absence of the dilator pupillae muscle.
• Few MCOR-affected families have been reported globally.

Purpose of the Study:

• To identify the genetic cause of congenital microcoria.
• To investigate the role of specific genes in iris development and function.

Main Methods:

• Whole-genome oligonucleotide array comparative genomic hybridization (CGH) was used.
• Breakpoint sequence analyses were performed on identified deletions.
• Segregation analysis within affected families was conducted.

Main Results:

• Deletions at chromosomal location 13q32.1 were identified in six MCOR-affected families.
• These deletions, ranging from 35 kbp to 80 kbp, consistently involved the TGDS and GPR180 genes.
• GPR180, encoding G protein-coupled receptor 180, is implicated in smooth muscle cell growth and is a likely candidate gene for MCOR.

Conclusions:

• Deletions disrupting the GPR180 gene are the cause of congenital microcoria.
• The function of GPR180 in smooth muscle cell regulation is crucial for proper iris dilator muscle development.
• This study establishes GPR180 as the causative gene for MCOR.