Dubowitz syndrome is a complex comprised of multiple, genetically distinct and phenotypically overlapping disorders

Area of Science:

• Genetics and Molecular Biology
• Rare Disease Research
• Genomic Medicine

Background:

• Dubowitz syndrome is a rare genetic disorder with diverse symptoms including congenital anomalies, growth failure, and immune defects.
• Phenotypic variability suggests underlying genetic heterogeneity, necessitating further molecular investigation.
• Previous studies have identified various genetic causes, but a comprehensive understanding remains elusive.

Observation:

• Exome sequencing in siblings revealed compound heterozygous mutations in the LIG4 gene (c.2440C>T and c.613delT).
• SNP genotyping in a third patient identified a de novo deletion on chromosome 17q24.2, encompassing the PRKAR1A gene.
• All three patients exhibited significantly shortened telomere length (≤1st centile) and increased radiosensitivity.

Findings:

• The identified LIG4 mutations led to an absence of ligase IV protein in the affected siblings.
• The 17q24.2 deletion is a novel genetic cause associated with Dubowitz syndrome.
• Shortened telomeres are a shared feature across different genetic subtypes of Dubowitz syndrome, LIG4 syndrome, and 17q24.2 deletions.

Implications:

• Dubowitz syndrome represents a spectrum of disorders rather than a single entity, requiring re-evaluation and re-definition.
• Telomere length assessment should be considered in the diagnostic workup for patients with LIG4 syndrome and 17q24.2 deletions.
• Understanding the genetic basis of these syndromes can lead to improved diagnostics and potential therapeutic strategies.