Human chromosome methodology / edited by Jorge J. Yunis.

Date:: 1965

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Human chromosome methodology / edited by Jorge J. Yunis. Source: Wellcome Collection.

245/280 page 227

$Human Chromosomes in Disease 227 Cases of regular trisomy Dj have been found associated with other chromosomal abnormalities in the same sibship. This relationship may be either a chance association or perhaps a consequence of a familial tendency to chromosomal aberrations. Examples of this situation are the association of trisomy and XO in the same sibship (Therman et al., 1961) and the occurrence of a D trisomy and triploidy in twin fetuses (Carr, 1963). 2. Translocation A very interesting family showing individuals with partial trisomy D, D ^ D balanced translocation, and partial loss of a D chromosome, has been described by Jacobsen et al. (1963). The partial loss of a D chromo¬ some was observed in a fetus, and the boy carrying the partial trisomy D showed mental deficiency and some congenital anomalies usually observed in trisomy Di syndrome. A familial D D translocation resulting from centric fusion of the long arms of two D chromosomes has been reported in a few instances. In the families described by Walker and Harris (1962), Hamerton et al. (1963), and Yunis et al. (19б4а), offspring of carriers were either normal individuals or D - D translocation carriers. A high incidence of miscarriage was also noted. Because of the possibility of these carriers having a ^^ D translocation, Yunis et al. (19б4а) studied the DNA replication of the abnormal chromosome in several members of one family and found it to be a D2 translocation chromosome (Fig. 13). Thus, carriers might produce trisomy offspring. Jagiello (1963) also described a familial D D balanced translocation due to centric fusion of the long arms of two D chromosomes. In the first generation, a phenotypically normal male with three stemlines (bal¬ anced D /-w- D translocation, monosomy D, and translocation trisomy D) was observed. Two of his daughters demonstrated two stemlines (bal¬ anced D D translocation and translocation trisomy D), but again, the daughters were phenotypically normal. 3. Mosaicism A patient bearing two cell populations, one normal and the other with 47 chromosomes, and an extra D chromosome, was briefly reported by one is late replicating over the long arm near the centromere (Dg), and two are earlier replicating (Dg). The two missing D chromosomes formed a DD translocating chromosome with the DNA replication pattern consistent with that of the long arms of a Dj^ and a Dg chromosome. (From Yunis et al., 1964a.) \$

Human chromosome methodology / edited by Jorge J. Yunis.

Licence and re-use

Contents