Leonard Prouty

A presumptive new hylobatid subgenus with 38 chromosomes.

The gibbon Hylobates hoolock has been found to possess a karyotype different in diploid number and banding pattern from that of any other hylobatid. We propose that the hoolock gibb

Uniparental isodisomy resulting from 46,XX,i(1p),i(1q) in a woman with short stature, ptosis, micro/retrognathia, myopathy, deafness, and sterility.

We report on a 43-year-old woman who was referred for evaluation because of minor facial anomalies, myopathy, sterility, short stature, hearing loss, downward slant of palpebral fissures, bilateral ptosis, severe micro/retrognathia, high arched palate, and scoliosis. Cytogenetic analyses utilizing GTG/CBG bandings showed presence of one i(1p) and one i(1q) without normal chromosome 1 homologues. Fluorescence in situ hybridization analysis showed hybridization to only two chromosomes, consistent with the G-banded interpretation of i(1p) and i(1q). To the best of our knowledge, this is the first case of isochromosomes 1p and 1q replacing the two normal chromosome 1s. Molecular investigations using markers for chromosome 1 showed inheritance of only one set of paternal alleles and absence of any maternal alleles in the patient. The adverse phenotype of the patient may be due to one or more recessive mutations, genomic imprinting, or a combination of both.

The parental origin and mechanism of formation of three dicentric X chromosomes

SummaryCytogenetic and molecular analyses of three dicentric X chromosomes were performed in an attempt to identify the parental origin and mechanism of formation of the aberant chromosomes. Results indicate that, in these three cases, the dicentric chromosomes were formed by chromatid breakage and reunion of sister chromatids at the breakpoint. In two cases the abnormal chromosomes were paternal in origin; in the third case the dicentric originated from the maternal X chromosome.

Non-mosaic trisomy 20 in amniotic fluid cultures with minor anomalies in the fetus

A non‐mosaic trisomy 20 was discovered in all cells in two separate cultures from an age‐related genetic amniocentesis. Karyotypes of cells obtained via amniocentésis at the time of termination and of cells cultured from the placenta gave the same unambiguous results. However, the fetus, under macro‐ and microscopic analysis, showed only two minor anomalies: left simian crease and low‐set ears. These findings are more suggestive of a normal or at most mosaic trisomy 20 state. The significance of this finding for prenatal diagnosis is discussed.

A case of insertional translocation involving chromosomes 2 and 4

We report on a 6‐year‐old Caucasian boy with direct insertion of genetic material from the short arm of chromosome 4 to the short arm of chromosome 2. He was referred for evaluation because of global developmental delay and seizure disorder. A karyotype performed at 41/2 months of age, by a laboratory elsewhere, reportedly showed a deletion of chromosome 4(p12). When we saw him, he had macrocephaly, hypotonia, psychomotor retardation, multiple minor congenital anomalies, and EEG abnormalities. Repeat chromosomes performed by our laboratory revealed that his karyotype was 46, XY, dir ins(2;4)(p24;p15.3p13).