A newborn with partial pure trisomy of chromosome 7q inherited from paternal balanced translocation with congenital anomalies. a mini review

Abstract

We report on a familial translocation t(3;7)(3q29::7q22) leading to pure trisomy 7q22 --> 7qter in a 21-days-old boy: 46,XY,der(3;7)(3pter--> 3q29::7q22--> 7pter). By conventional citogenetic techniques including fluorescence in situ hybridization (FISH) analysis, the patient was found to have inherited a derivative chromosome 3 from his father: 46,XY,t(3;7)(3pter--> 3q29::7q22--> 7qter;7pter--> 7q22). As a consequence, pure duplications of chromosome 7q have been classified in 4 groups on the basis of the involved region. The present case is included in group 2 which involves large duplications spanning from proximal bands to telomere duplication. In the literature, only one case with a pure duplication of the same region has been described. Despite this, the phenotype is different. Moreover, our patient shares some phenotypic features, such as wide fontanelle, retrognathia, epicathal fold, hypertelorism, pulmonary hypoventilation and early postnatal death. However, the absence of physical characterization in most of the reported cases could justify the lacking phenotype-genotype correlation in patients with partial 7q duplication. Further studies using recent molecular approaches such as array-CGH might permit a more clinically useful grouping of 7q duplications.