Whole Exome Sequencing Reveals Compound Heterozygosity for Ethnically Distinct PEX7 Mutations Responsible for...

Area of Science:

• Genetics
• Biochemistry
• Pediatrics

Background:

• Rhizomelic chondrodysplasia punctata type 1 (RCDP1) is a rare peroxisome biogenesis disorder.
• Patients typically present with skeletal abnormalities, developmental delay, and distinctive facial features.

Purpose of the Study:

• To identify the genetic cause of severe intellectual and physical disability in two brothers with unexplained symptoms.
• To characterize novel mutations in the peroxisome biogenesis factor 7 (PEX7) gene associated with RCDP1.

Main Methods:

• Clinical evaluation of two affected brothers presenting with bone growth abnormalities and progressive neurological decline.
• Whole exome sequencing (WES) to identify genetic variants.
• Segregation analysis of identified mutations within the family.

Main Results:

• Both brothers were found to have compound heterozygous stop mutations in the PEX7 gene.
• One mutation, p.Arg232(*), previously reported only in a Japanese family, was identified in these European-descent patients.
• The second mutation, p.Leu292(*), is common in RCDP1 patients.
• This coinheritance of p.Arg232(*) and p.Leu292(*) mutations in RCDP1 is reported for the first time.

Conclusions:

• Whole exome sequencing is a valuable tool for diagnosing rare genetic disorders like RCDP1 with complex phenotypes.
• The identification of these specific PEX7 mutations expands the known spectrum of genetic variations causing RCDP1.
• The presence of the p.Arg232(*) mutation in individuals of European descent suggests wider ethnic distribution than previously documented.