Antenatal genetic diagnosis in a kindred with a 15p+ chromosome

Abstract

Karyotype studies arc reported in 15 members of a kindred, a 15p+ marker chromosome being present in six of the members, including the proband as well as her mother and aunt. The proband was a Down's syndrome patient with a regular trisomy‐21 besides the marker chromosome. The marker chromosome could represent a Y/15 translocation, as judged from morphology and an intensive fluorescence of the extra material, or it could possibly be interpreted as a giant satellite. In relation to a case of genetic counseling in the aunt, including prenatal diagnosis, the question whether the marker chromosome may imply an increased risk of pathologic offspring is considered.

Y/autosomal translocations

“…The most common type is clearly Y/15 of unbalanced type (der(lS),t(lS;Y)(pl2,13; q12)). Only three cases were apparently de n o w balanced translocations: a Y/15 translocation described by Pfeiffer et al (1973), a Y/21 translocation described by Hahnemann & Eiberg (1973), and a Y/5 translocation described by Dutrillaux & Gueguen (1975). All other cases described were unbalanced with presumptive extra Y material translocated to an autosome.…”

A prenatally discovered unbalanced translocation t(14;22) (q22 or 23;q13)

“…Up to the present, most of the work has been devoted to technical problems connected with the sampletaking, culture and chromosome determination of cells from the amniotic fluid. Many authors (including BUTLER and REISS 1970, COWIE 1971, HAHNEMANN and EIBERG 1973and WAHLSTROM 1973, however, have also emphasised the importance of advice-giving and information as to what chromosome determination involves in the widest sense, already before samples are taken. One of the aims of such a procedure is to create the conditions for an investigation that will cause as little trauma as possible.…”