Microduplication in the 2p16.1p15 chromosomal region linked to developmental delay and intellectual disability

Area of Science:

• Genetics
• Human Genetics
• Chromosomal Abnormalities

Background:

• The 2p16.1p15 microdeletion syndrome is documented, but microduplications in this region are rare.
• Only one prior case of 2p16.1p15 microduplication was reported, showing milder features than deletions.
• Additional cases were identified in the DECIPHER database.

Observation:

• Four new, unrelated individuals with 2p16.1p15 microduplication were identified.
• Presenting symptoms included mild gross motor delay, speech and language delays, and subtle dysmorphic features.
• Two individuals had macrocephaly, and one had a congenital heart anomaly.

Findings:

• Common features include developmental delay, speech delay, mild to moderate intellectual disability, and nonspecific dysmorphic features.
• Specific findings included bilateral clinodactyly of the 5th finger and bilateral 2nd-3rd toe syndactyly in some patients.
• Unlike microcephaly seen in deletions, macrocephaly was observed in two patients with microduplication.

Implications:

• The 2p16.1p15 microduplication is suggested to be causally associated with developmental delays, speech impairments, and mild intellectual disability.
• This study expands the phenotypic spectrum of 2p16.1p15 chromosomal region copy number variations.
• Further research is warranted to fully understand the genotype-phenotype correlations of this region.