Characterization of a cryptic 3.3 Mb deletion in a patient with a "balanced t(15;22) translocation" using high density oligo array CGH and gene expression arrays.

摘要: Patients with an apparently balanced translocation and abnormal phenotype may carry a cryptic deletion/duplication at their breakpoints that explain abnormalities. Using microarray CGH (aCGH) gene expression arrays we studied child t(15;22)(q26.1;q11.2), developmental delay mild dysmorphic features. A high density aCGH study 244,000 oligo probes demonstrated 3.3 Mb deletion immediately adjacent to the 15q breakpoint. Gene studies 44,000 oligos displayed approximately 50% reduction of IGF1R was translocated der(22). There are 18 known or hypothetical protein coding genes within deleted region according UniProt, RefSeq, GenBank mRNA (UCSC HG17, May 2004). Although two these genes, RGMA ST8SIA2, play important role in neural development, our patient indicates loss one copy not be critical developmentally. The could responsible for growth deficiency patient. Reviewing few 15q26 microdeletion cases have been characterized by aCGH, discovered segment including distal 15q26.2 proximal part 15q26.3 is associated severe phenotypes. Our experience demonstrates high-density oligonucleotide-based quick precise way identify number changes "balanced translocations." Expression can also add valuable information regarding due chromosomal rearrangement. Both approaches assist elucidation etiology unexplained phenotypic differences such as this one.