Clinical, cytogenetic and molecular study in a case of r(3) with 3p deletion and review of the literature.

Ring chromosome 3 is a rare abnormality with only 10 patients described in the literature. We report a patient with r(3) and ∼6-Mb distal 3p deletion. Single nucleotide polymorphism array, multiplex ligation-dependent probe amplification and fluorescence in situ hybridization techniques revealed that the ring was formed by a break in 3p26.1 and fusion with the subtelomeric region of 3q. The patient presents delayed psychomotor development, growth failure, minor anomalies and other features similar to patients with 3p monosomy. The analysis of 300 metaphase cells using G-banding and fluorescence in situ hybridization with centromeric probe revealed ring instability resulting in cells with secondary aberrations and with ring loss that could also be related to some phenotypic characteristics such as growth delay. This is the first patient with r(3) studied using molecular techniques that determined the exact breakpoints in order to establish a better karyotype-phenotype correlation.