A three chromosome translocation involving two homologous chromosomes in a trisomic abortus

Unexpected Inheritance of a Balanced Homologous translocation t(22q;22q) from father to a phenotypically normal daughter

Rearrangements between homologous chromosomes are extremely rare and manifest mainly as monosomic or trisomic offsprings. There are remarkably few reports of balanced homologous chromosomal translocation t (22q; 22q) and only two cases of transmission of this balanced homohologous rearrangement from mother to normal daughter are reported. Robersonian translocation carriers in non-homologous chromosomes have the ability to have an unaffected child. However, it is not possible to have an unaffected child in cases with Robersonian translocations in homologous chromosomes. Carriers of homologous chromosome 22 translocations with maternal uniparental disomy do not have any impact on their phenotype. We are presenting a family with a history of multiple first trimester miscarriages and an unexpected inheritance of balanced homologous translocation of chromosome 22 with paternal uniparental disomy. There are no data available regarding the impact of paternal UPD 22 on the phenotype. We claim this to be the first report explaining that paternal UPD 22 does not impact the phenotype.

A complex chromosomal rearrangement detected prenatally and studied by fluorescence in situ hybridization

We report of case of a complex chromosomal rearrangement detected prenatally and studied with traditional banding methods and fluorescence in situ hybridization. The combination of these techniques showed that four chromosomes were involved in the translocation. Nine breakpoints were proposed to explain these results. Some of the findings could only be detected with fluorescence in situ hybridization, demonstrating the usefulness of this technique in characterizing chromosomal abnormalities that would otherwise be difficult to interpret correctly with classical cytogenetics alone.

Mosaic Down's syndrome with de novo 45,XX,-21,-22,+t(21q;22q)/46,XX,-21,+t(21q;21q) rearrangement

The occurrence of mosaic Down's syndrome with two independent Robertsonian translocation cell lines is very rare. Such a patient is reported here, in whom an unbalanced Robertsonian translocation between two chromosomes 21 was detected in the majority of cells. The patient also revealed a minor cell line with a second Robertsonian translocation involving a chromosome 21 and a 22. The chromosome translocations detected in this patient were de novo in origin.

A cytogenetic study of human spontaneous abortions using banding techniques

The karyotypes of 941 singleton and 42 twin abortuses and 4 cystic placentae were determined. 30.5% of the singletons were chromosomally abnormal; 49.8% of these were trisomic, 23.7% X-monosomics and 17.4% polyploid. 143 trisomies were identified by banding; over a third had an extra chromosome 16, more than 10% an extra 21 or 22 and about 5% an extra 2, 18 or 15. Examples of trisomy 3, 4, 8, 9, 10, 13, 14 and 20 were also encountered. Using the data from two other published studies, the prevalence of different trisomies was estimated and an attempt was made to relate the karyotype of the conceptus to its subsequent development.