[Show abstract][Hide abstract] ABSTRACT: A case of pure 12p trisomy was discovered in a 14-year-old boy during a cytogenetic survey of Egyptian students attending a school for mentally retarded children. The patient had a normal birth weight but later showed developmental delay. Clinical examination at 14 years of age revealed a high bulging forehead, broad and flat nasal bridge, large mouth with everted lower lip, folded upper ear helix with protuberant antihelix, pectus excavatum, undescended testes, flat feet, generalized hypotonia and moderate mental retardation. Chromosomes analyzed from blood lymphocytes showed an enlarged short arm with an additional band on one of the no. 12 chromosomes. The duplicated chromosomal material extended from 12pter----p12.2, including the LDH-B locus, which showed a gene-dosage effect. This extra chromosomal material arose de novo by tandem duplication. The parents' chromosomes were normal.
Full-text · Article · Jun 1989 · Clinical Genetics
[Show abstract][Hide abstract] ABSTRACT: We have studied two sisters with partial deletion 9p and partial duplication 18q resulting from adjacent 1 segregation of a maternal translocation (9;18) (p22;q21.3). The clinical manifestations identified in our patients were compared with those reported in the literature for 9p- and 18q+ patients involving approximately the same amount of genetic material. There was relatively greater similarity with the 9p- syndrome than with dup (18q) syndrome, but typical characteristics of both conditions were lacking.
Full-text · Article · Dec 1988 · American Journal of Medical Genetics
[Show abstract][Hide abstract] ABSTRACT: The gene for human galactosyltransferase (EC 18.104.22.168) has been localized to the short arm of chromosome 9 by in situ hybridization to human metaphase chromosomes of a 985 bp cDNA probe for the gene.
No preview · Article · Jan 1987 · Biochemical and Biophysical Research Communications
[Show abstract][Hide abstract] ABSTRACT: A ring 13 chromosome was identified in an infant whose chromosomes were studied because of microcephaly. The ring chromosome was studied over a 3-year-period in lymphocytes, and in both short- and long-term fibroblast cultures. Lymphocyte cultures revealed a consistently stable ring 13 chromosome with minimal loss of genetic material (the distal portion of band q34). Fibroblast cultures contained a ring chromosome a quarter of the size of the original ring and this chromosome was unstable in short- and long-term cultures. The patient's mild dysmorphic features and moderate mental retardation correlate with a stable ring chromosome in which only a small amount of genetic material has been lost rather than with the unstable small ring 13 chromosome observed in fibroblast cultures. The observation of drastic tissue specific differences in ring sizes and stability makes phenotypic karyotypic correlations with ring chromosome patients even more difficult and counselling in cases of prenatal diagnosis questionable.
No preview · Article · Jan 1987 · Journal of mental deficiency research
[Show abstract][Hide abstract] ABSTRACT: We have studied female cousins with partial duplication of 12q. The cousins' mothers (who are sisters) and the maternal grandmother and great grandmother carried a balanced translocation between chromosomes 11 and 12. We have compared our patients with eight other reported cases of partial duplication of the same chromosome segment (12q24----12qter). Placement of the extra material seems to have little effect on the anomalies present; (only two other cases involved chromosome 11). We propose that our patients provide further evidence that duplication of 12q leads to a clinically identifiable syndrome.
No preview · Article · Aug 1986 · American Journal of Medical Genetics
[Show abstract][Hide abstract] ABSTRACT: Double aneuploidy involving Down syndrome and Turner syndrome is a rare chromosomal abnormality presumed to occur with a frequency of about 1 in 2 million births. Twenty-one cases of this combined anomaly have been reported and two infants were born with this anomaly after a mistake in prenatal diagnosis. We report the first prenatal diagnosis of Down syndrome combined with Turner mosaicism and suggest that this polysyndrome may be more common than previously estimated. We, therefore, wish to alert cytogenetic laboratories performing prenatal diagnoses of the potential risks of misdiagnosis of this polysyndrome if banding is not performed and if a sufficient number of mitotic cells are not analysed.
No preview · Article · Jul 1985 · Prenatal Diagnosis
[Show abstract][Hide abstract] ABSTRACT: Although correction for underreporting of congenital malformations on birth certificates is included in most studies, inaccuracy of reporting has not been widely examined. Two separate investigations were conducted on the inaccuracy of Down syndrome (DS) reporting on birth certificates; ie, false-positive cases in which an individual coded as DS did not in fact have DS. In Ohio, 824 individuals were coded as DS on their birth certificate during 1970–1981. Of these, a definitive determination as to whether or not they had DS was made on 778 by using cytogenetic data, medical records, the state's birth defects registry, school records, and by questioning physicians. Fifty-seven false-positives were found, indicating a 7.8% level of coding inaccuracy for all races and 6.9% for whites only. Nine of these arose from miscodings during data processing; 48 were misdiagnosed as DS. This can be contrasted with false-negatives also studied in Ohio, where 66.1% of DS cases were not reported on the birth certificate. No statistical differences were observed between false-positives and true DS in the distribution of sexes, in population size of county of birth, or in year of birth (although there was a declining false-positive rate over the 12 year period). The percentage of DS false-positives, however, was significantly higher for younger maternal ages (⩾30 years) than older ones (⩾30 years) and for nonwhites compared to whites. Further, there was a strong negative correlation between the percentage of false-positives and the degree of certainty expressed in reporting DS on the birth certificate.
No preview · Article · Jan 1985 · Genetic Epidemiology