The phenotype of ring chromosome 3

Area of Science:

• Genetics
• Clinical Dysmorphology
• Human Molecular Genetics

Background:

• Ring chromosome 3 (r(3)) is a rare chromosomal abnormality.
• Identifying specific breakpoints is crucial for understanding genotype-phenotype correlations.

Observation:

• A male child presented with mental retardation, poor growth, and a 46,XY,r(3)(p26-q29) karyotype in lymphocytes and fibroblasts.
• Dysmorphic features included microcephaly, hypertonia, digital anomalies, and a characteristic facial appearance.

Findings:

• The patient's phenotype aligns with a syndrome primarily caused by a deletion of the 3p26 to pter region.
• The ring chromosome 3 likely resulted in a terminal deletion of the short arm.

Implications:

• This case refines the understanding of the 3p deletion syndrome.
• It highlights the importance of detailed cytogenetic analysis in patients with unexplained developmental disorders.