Phenotypic and molecular characterisation of a de novo 5q deletion that includes the APC gene.

We report on a 12-year-old female patient with mild dysmorphic signs, including bilateral epicanthal folds, low-set dysplastic ears, a short nose with anteverted nostrils, conically shaped fingers, generalised increase of subcutaneous fat, multiple fine venous teleangiectasia on her back, mild pectus carinatum, and a general muscular hypotonia. Cytogenetic analysis and fluorescence in situ hybridisation (FISH) studies using region-specific BAC and YAC clones indicated a de novo interstitial deletion of the long arm of chromosome 5, resulting in monosomy 5q21.1-q23.1. Molecular analysis of polymorphic markers helped to narrow down the breakpoints and demonstrated that the derivative chromosome 5 is of paternal origin. By using the same panel of polymorphic markers, a reinvestigation of a similar, already published, 5q deletion case [Raedle et al. (2001) Am J Gastroenterol 96:3016-3020] was performed, allowing a more detailed genotype-phenotype correlation. Phenotypic classification was also carried out. Several known genes, including APC and MCC, were found to map to the common deleted genomic segment. Genetic counselling based on the molecular analysis data was performed for the index family.