Distal 5q deletion syndrome: phenotypic correlations

Area of Science:

• Genetics
• Developmental Biology
• Clinical Medicine

Background:

• Partial monosomy of chromosome 5 (5q deletion) is a rare chromosomal abnormality associated with developmental and congenital anomalies.
• Understanding the specific genetic underpinnings of 5q deletions is crucial for diagnosis and potential therapeutic strategies.

Observation:

• Two male siblings presented with distinct phenotypes resulting from a maternally derived partial monosomy of chromosome 5.
• Affected individuals exhibited microcephaly, facial anomalies, central nervous system (CNS) malformations, and cardiac septal defects (atrial septal defect and ventricular septal defect).
• Specific breakpoints in the 5q deletion were identified, differing from previously reported cases.

Findings:

• Both siblings displayed developmental delay and facial anomalies, consistent with other reported cases of 5q deletions.
• Cardiac septal defects were present in both patients, with a potential link to the deletion of the cardiac-specific hCSX gene, as evidenced by its single copy in affected individuals.
• While CNS and cardiac issues are noted, other phenotypic components remain unlinked to currently identified genes within the deleted segments.

Implications:

• This study expands the known spectrum of phenotypes associated with 5q deletions, particularly those distal to 5q33.
• The findings suggest a role for the hCSX gene in the etiology of cardiac septal defects in this patient cohort.
• Further research is needed to identify other genes within the deleted 5q segments that contribute to the observed developmental and congenital anomalies.