Analphoid 3qter markers

Area of Science:

• Human Genetics
• Cytogenetics
• Molecular Biology

Background:

• Investigating marker chromosomes originating from non-centromeric locations is crucial for understanding chromosomal stability and function.
• The presence of functional centromeres on these aberrant chromosomes influences their behavior during cell division.

Observation:

• Two cases presented with marker chromosomes derived from the 3qter region, exhibiting mosaicism.
• Clinical features included developmental delay, seizures, and dysmorphic features such as preauricular pits and hypopigmentation.
• Marker chromosomes showed a constriction but were C-band negative, with specific centromeric protein (CENP-C, CENP-E) presence and CENP-B absence.

Findings:

• Marker chromosomes from non-centromeric regions can acquire functional centromeres, indicated by the presence of key centromeric proteins.
• Despite the presence of functional centromeres, a distinct clinical phenotype associated with tetrasomy for the 3q26.2-3qter region could not be definitively established in these cases.

Implications:

• These findings challenge traditional understanding of centromere formation and function.
• Further research is needed to elucidate the long-term consequences and potential phenotypic spectrum of such non-centromeric marker chromosomes.