CHARACTERIZATION OF A DERIVATIVE CHROMOSOME-17 BY FISH-TECHNIQUE

We report a case with derivative chromosome 17 which could not be char acterized by routine G-banding, since the additional material on 17q o verlapped 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 speci fic probes were used to identify the abnormality by FISH-technique whi ch revealed a 46,XY, der (17) t (4;17) (p15.2;q25) karyotype. The prob and was partially trisomic for 4p15.2 --> pter and monosomic for the d istal 17q25 --> qter regions. The major clinical features included: an ti-mongoloid slanted palpebrae, coloboma of right iris, depressed nasa l bridge, high arched palate, protruding tongue, micrognathia and smal l penis. The MRI of the brain revealed midly hypoplastic cerebellar ve rmis, and a normal septum pellucidum. The infant responded to therapy for hypoglycemia and was discharged under stable condition. Prior to c ytogenetic evaluation the infant was not recognized as either ''trisom y 4p syndrome'' or ''monosomy 17q syndrome''.