engleski

Detection of De Novo Partial Trisomy 22qter

Characterization of a small chromosomal segment by means of conventional cytogenetics, even when high resolution banding is applied, can be inconclusive. The identification of the origin of duplicated chromosomal material on 22p, otherwise very difficult to characterize, is offered as an example. It was done using the FISH. The analysis of peripheral lymphocytes from the propositus by means of conventional cytogenetics with standard resolution, was normal. The FISH with cosmid N85A3, which normally hybridizes to the terminal region of the chromosome 22 long arm, revealed 3 signals, two of which corresponded to the normal position, and one was found on the short arm of the derivate chromosome 22. The causes of the distal chromosome segment duplication often lead to the familial pericentric inversion, parents with the same probe having normal signals on the terminal position of the chromosome 22 long arm. Segmental aneusomy was not detected at original cytogenetic diagnosis because the extra material on the chromosome 22 short arm was compatible with polymorphism of the satellite region of 22p. Clinical features of this 3-year-old boy with a rare de novo chromosomal aberration was growth retardation at birth, mental and developmental retardation, including a smaller mandible, genital hypospadia, testicular retention, ventricular and pulmonary stenosis. The authors suggest a possible association of the patient’ s clinical features with the duplicated material at the distal part of chromosome 22 long arm.

De novo partial trisomy 22qter; FISH

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