Characterization of a derivative chromosome 17 by FISH-technique

We report a case with derivative chromosome 17 which could not be characterized by routine G-banding, since the additional material on 17q overlapped with chromosome bands 2q35 → qter, 3p25 → pter, 4p15 → pter, 5q33 → qter, 7p15 → pter, 12p11.2 → pter, 14q24 → qter and 16q22 → qter. Therefore, whole chromosome paint and region specific probes were used to identify the abnormality by FISH-technique which revealed a 46,XY, der (17) t (4;17) (p15.2;q25) karyotype. The proband was partially trisomic for 4p15.2 → pter and monosomic for the distal 17q25 → qter regions. The major clinical features included: anti-mongoloid slanted palpebrae, coloboma of right iris, depressed nasal bridge, high arched palate, protruding tongue, micrognathia and small penis. The MRI of the brain revealed midly hypoplastic cerebellar vermis, and a normal septum pellucidum. The infant responded to therapy for hypoglycemia and was discharged under stable condition. Prior to cytogenetic evaluation the infant was not recognized as either << trisomy 4p syndrome >> or << monosomy 17q syndrome >>.