Microdeletion 19p13.2 in an almost 5-year-old boy

Area of Science:

• Genetics
• Genomics
• Molecular Biology

Background:

• Deletions on the short arm of chromosome 19 (19p) are challenging to detect with conventional cytogenetics due to high gene density.
• Previously, 19p deletions were associated with severe phenotypes, but advances in high-resolution array techniques have enabled identification of more cases.

Observation:

• A nearly 5-year-old boy presented with intellectual disability, minor dysmorphic features, and febrile seizures.
• Genetic analysis revealed a de novo deletion of 834.2 kb on chromosome 19p13.2, encompassing 32 genes.

Findings:

• The deletion was identified using SNP-array (Illumina Infinium HD Human1M-Duo v1 BeadChip) and confirmed by CGH-array (NimbleGen Human CGH 2.1M Whole Genome Tiling v2.0D).
• Breakpoint sequencing indicated that the deletion was formed via non-allelic homologous recombination (NAHR).

Implications:

• This case demonstrates that microrearrangements on gene-dense chromosomes can result in milder clinical consequences than previously assumed.
• The findings underscore the importance of high-resolution genetic technologies for diagnosing complex genetic disorders and understanding genotype-phenotype correlations.