Characterization of a 5.8-Mb interstitial deletion of chromosome 3p in a girl with 46,XX,inv(7)dn karyotype and phenotypic abnormalities.

Interstitial deletions of the short arm of chromosome 3 are rare, and a specific clinical phenotype has not been defined. We report the first isolated cryptic proximal interstitial 3p deletion, del(3)(p12.3p13), assessed by array-based comparative genomic hybridization in a girl with an inversion of chromosome 7, whose phenotype includes neurodevelopmental delay, growth retardation, dysmorphic facial features, hypophysis hypoplasia, gastroesophageal reflux, clinodactyly, preauricular appendix, and myopia. Her features are similar to those observed in the previously reported cases of proximal 3p deletions overlapping with our imbalance, indicating that her clinical manifestations are likely to be due to the deletion. As our patient's imbalance is the first non-cytogenetically visible proximal interstitial 3p deletion uncomplicated by other imbalances, its characterization has allowed us to narrow the minimal deletion interval associated with growth retardation and neurodevelopmental delay to the 3p12.3-p13 region. Among the genes found in this region, ROBO1, ROBO2, PDZRN3 and CNTN3 might play a role in the neurodevelopmental delay of the patient. This study provides additional evidence that cryptic imbalances anywhere along the genome can be found in patients with phenotypic abnormalities and a balanced chromosome rearrangement.