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Biomedical subjects

D C Peakman

Publications and source records attributed to D C Peakman.

15 recordsLinked to original sources
PubMed1981

Amniocyte clones for prenatal cytogenetics.

Amniotic fluid cells were processed in situ on coverslips in 1,429 consecutive cases from Colorado and Arizona. Two true chromosome mosaics were differentiated from 39 pseudomosaics with clarity by the method described here in detail. The culture failure rate was 1--2% and the error rate was 0% in both laboratories. The time in culture prior to the initial harvest for the last 329 cases was 8.7 days.

Amniotic Fluid↗
PubMed1981

Familial pericentric inversion of chromosome 8.

Eight children from seven presumably unrelated families were identified independently as having an unbalanced recombinant chromosome resulting in the presence of extra material on the short arm of a chromosome 8. Parental chromosomes were analyzed, and one member of each couple (four fathers and three mothers) was found to carry a pericentric inversion of a chromosome 8 [inv(8)(p23q22)]. The propositi had an unbalanced recombinant chromosome [rec(8),dup q,inv(8)(p23q22)]. The affected infants all had developmental delay, congenital heart disease, and unusual appearance. A common origin of the pericentric inversion was suggested because of geographic location and Mexican--American ancestry of the seven families.

Child↗
PubMed1979

Chromosome deletion [46,XX,del(20)(q11)] in agnogenic myeloid metaplasia.

A woman in the fourth year of agnogenic myeloid metaplasia was found to have partial deletion of the long arm of chromosome 20 [46,XX,del(20)(q11)] in mitoses of presumably immature myeloid cells from unstimulated cultures of peripheral blood and bone marrow. Cytogenetic studies of peripheral blood lymphocytes showed a normal female karyotype.

Blood Transfusion↗
PubMed1979

Chromosomal mosaicism in amniotic fluid cell cultures.

Over the past 6 years, using in situ processing methods, we have identified 32 cases of mosaicism in amniotic fluid cell cultures prepared from 1,100 samples. Two of these (45,X/46,XX and 46,XX/47,XX, + 21) were called true mosaics because multiple colonies demonstrated the same abnormal chromosome complement, and on subsequent evaluation of the newborn blood or fetal tissues, mosaicism was confirmed. Of the remaining cases, 29 were designated as pseudomosaics because only single or partial colonies exhibited an aberrant chromosome complement, 12 having a trisomy 2 line. In the final case, a double trisomy was demonstrated in only one of eight colonies in the first culture, but in the culture from a repeat sample an additional two colonies showed the same double trisomy. Since no abnormal cells were observed in infant blood, it was postulated that the mosaicism may only have been present in the extraembryonic tissues. It is our conviction that the use of these cloning methods should diminish the danger of misdiagnosis in genetic amniocentesis.

Amniotic Fluid↗
PubMed1978

Prenatal genetic diagnosis: nine years experience.

The advent of techniques for the prenatal diagnosis of disease represents one of the most important advances in clinical genetics of the past decade. It has made it increasingly possible for parents to make informed decisions about reproduction. Physicians should think of genetic amniocentesis as one more method of assessing the status of a fetus at risk. It should be undertaken for a medical indication only, but the safety and accuracy are sufficiently established for it to be considered an integral part of providing high risk obstetrical care.

Adult↗
PubMed1977

Two cases of Down syndrome with unusual de novo translocation.

Two children with the clinical features of Down syndrome were found to have several unusual cell lines. In both cases the same reverse tandem translocation between two 21 chromosomes was present in one line. This may be an unstable rearrangement. In addition, the findings offer some support for current efforts to localize the portion of chromosome 21 responsible for clinical features of Down syndrome to band 21q22. Acridine orange R banding was found to be especially useful in the identification of the break points on the translocations. The origin of the abnormality was found to be paternal in one case and was indeterminate in the second.

Cell Line↗
PubMed1977

Prenatal diagnosis: techniques used to help in ruling out maternal cell contamination.

The combined findings from a number of different analytical techniques increases confidence that the cells analysed in amniotic fluid cell cultures are fetal in origin. Three hundred and twenty four fluids were processed using in situ processing of cultured amniotic fluid cells, allowing for analysis of mitoses from multiple colonies derived from multiple culture dishes. Screening of the same samples for fluorescent Y-chromatin was of help in indicating the genotypic sex of the primary cells. This was found to be accurate in 96% of the fluids checked. In cases where an XX complement is found, Q-polymorphism comparisons can be made between mitoses from the amniotic fluid cells and maternal lymphocytes. Of 29 such studies, 19 showed pronounced differences in their polymorphism constitution.

Amniocentesis↗
PubMed1976

Comparison of G-, Q-, and R-banding in 28 cases of chromosomal abnormalities.

Twenty-eight cases of chromosomal abnormalities were ascertained using G-banding. Seventeen of these had structural abnormalities of a complex nature and are discussed in detail. An independent assessment of chromosome abnormalities was carried out using sequential Q- and R-banding. In no case was there a difference in the identification of the abnormal chromosome, but in two cases a more precise localization or definition of the abnormality was obtained from the R-banded cells. In one case the initial diagnosis of the terminal deletion was altered to interstitial deletion; in the second case a break point in one chromosome involved in a reciprocal translocation was found to be in a different band by R-banding. In several others better delineation of break points or confirmation of complex abnormalities was obtained from the R-banded cells. R-banding was especially helpful in the localization of break points because of the color differentiation obtained with acridine orange. Q-banding was not found to have added any additional information. It was concluded from this study that the use of both G-banding and R-banding in complex abnormalities proved worthwhile.

Chromosome Aberrations↗
PubMed1975

Missing Y chromosome in juvenile chronic myelogenous leukemia.

A child with Ph1-negative juvenile chronic myelogenous leukemia (CML) is presented. The only chromosomal abnormality in hematopoietic tissues consisted of an absent Y chromosome. While a missing Y chromosome in adult patients with CML may be associated with a better prognosis, the clinical course in our patient was as malignant as that usually observed in other children with Ph1-negative juvenile CML.

Aneuploidy↗