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Biomedical subjects

J W Dixon

Publications and source records attributed to J W Dixon.

13 recordsLinked to original sources
PubMed1994

Partial trisomy for 2q in a patient with dir dup(2) (q33.1q35).

A 22 year old woman with partial trisomy for the long arm of chromosome 2 is described. The karyotype is 46,XX, dir dup(2)(q33.1q35) de novo confirmed by FISH using a chromosome 2 specific paint. Parental chromosome studies were normal. To our knowledge this is the first report of trisomy for this specific segment of 2q and only the sixth case of de novo direct duplication of 2q, one of which was mosaic. Clinical features include epicanthus, clinodactyly, scoliosis, broad, flat nasal bridge, thin upper lip, long philtrum, and short neck.

Abnormalities, Multiple↗
PubMed1994

Bloom syndrome and maternal uniparental disomy for chromosome 15.

Bloom syndrome (BS) is an autosomal recessive disorder characterized by increases in the frequency of sister-chromatid exchange and in the incidence of malignancy. Chromosome-transfer studies have shown the BS locus to map to chromosome 15q. This report describes a subject with features of both BS and Prader-Willi syndrome (PWS). Molecular analysis showed maternal uniparental disomy for chromosome 15. Meiotic recombination between the two disomic chromosomes 15 has resulted in heterodisomy for proximal 15q and isodisomy for distal 15q. In this individual BS is probably due to homozygosity for a gene that is telomeric to D15S95 (15q25), rather than to genetic imprinting, the mechanism responsible for the development of PWS. This report represents the first application of disomy analysis to the regional localization of a disease gene. This strategy promises to be useful in the genetic mapping of other uncommon autosomal recessive conditions.

Bloom Syndrome↗
PubMed1993

Mosaicism for duplication 12q (12q13-->q24.2) in a dysmorphic male infant.

We report the clinical findings in a boy with mosaicism for a duplication of chromosome 12q13.1-->q24.2. His clinical characteristics are very similar to previously reported mosaic duplications of the distal long arm of 12, as well as several cases with non-mosaic duplications. It is proposed that this represents a clinically distinguishable syndrome for 12q duplication, in mosaic or non-mosaic form.

Abnormalities, Multiple↗