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C C Morton

Publications and source records attributed to C C Morton.

178 records · Page 10Linked to original sources
PubMed1985

Detection of a frequent restriction fragment length polymorphism in the human T cell antigen receptor beta chain locus. A potential diagnostic tool.

Abnormal T cell function is a feature of a spectrum of inherited and acquired diseases. We have detected a frequent restriction fragment length polymorphism in the human T cell antigen receptor beta-chain locus that may aid in the analysis of these disorders. A study of a panel of 18 normal individuals, testing for the presence of the polymorphism, showed it to account for 36% of the alleles in that group. In view of the fact that the T cell receptor beta-chain locus has been mapped to chromosome 7, and that the disease ataxia telangiectasia (AT) is associated both with abnormal T cell function and with chromosomal abnormalities of the same region of chromosome 7, we investigated the possibility that the polymorphism could demonstrate linkage of the T cell receptor locus to the gene for that disease. We demonstrated that the mutation causing AT did not lie within the beta-chain locus itself, and that there was preliminary evidence that the two loci were not closely linked. This polymorphism may provide a useful tool for the study of other genetic disorders associated with abnormalities of T cell function, as well as disorders associated with inherited or acquired abnormalities of chromosome 7.

Ataxia Telangiectasia↗
PubMed1984

Mapping of the human Blym-1 transforming gene activated in Burkitt lymphomas to chromosome 1.

Blym-1, a transforming gene detected by transfection of NIH 3T3 cells with DNA from Burkitt lymphomas, was mapped to the short arm of chromosome 1 (1p32) by chromosomal in situ hybridization. The Blym-1 gene was not physically linked to the cellular myc oncogene or to any of the immunoglobulin gene loci implicated in the characteristic chromosomal translocations in Burkitt lymphoma.

Base Sequence↗
PubMed1984

The human homologs of the raf (mil) oncogene are located on human chromosomes 3 and 4.

Two human genes that are homologous to both the murine transforming gene (oncogene) v-raf and the chicken transforming gene v-mil have been mapped by means of human-rodent somatic cell hybrids to human chromosomes previously devoid of known oncogenes. One gene, c-raf-2, which appears to be a processed pseudogene, is located on chromosome 4. The other gene, c-raf-1, which appears to be the active gene, is located on chromosome 3 and has been regionally mapped by chromosomal in situ hybridization to 3p25. This assignment correlates with specific chromosomal abnormalities associated with certain human malignancies.

Adenocarcinoma↗
PubMed1984

Orientation of loci within the human major histocompatibility complex by chromosomal in situ hybridization.

We have determined the localization and orientation of two genetic probes within the human major histocompatibility complex by chromosomal in situ hybridization. Our data indicate that a cloned genomic probe cross-hybridizing to HLA-A, -B, and -C heavy chain loci is homologous to sequences located on chromosome 6 at band p21.3 while a subclone of the genomic HLA-DR alpha-chain gene corresponding to the nonpolymorphic p34 protein is homologous to sequences in band 6p21.1. Our data suggest that this technique may permit the estimation of map distances between linked gene loci, assuming a uniform frequency of map units in the human genome. The relative positions of these genes was confirmed in a mother and son carrying a chromosome rearrangement involving 6p and 14p in which the sequences hybridizing to a DR alpha-chain genomic clone were found at the distal end of the 6p--chromosome [der(6)] while the sequences hybridizing to the HLA-A, -B, -C alpha-chain probe were found in the 14p+ chromosome [der(14)].

Chromosome Mapping↗
PubMed1984

Recent evolution of DNA sequence homology in the pericentromeric regions of human acrocentric chromosomes.

A search for genes located on human chromosome 21 resulted in the isolation of a HeLa cDNA clone, pUNC724, which hybridized to 3.7 and 2.5 kilobase (kb) EcoRI fragments on each of the human acrocentric chromosomes. In situ hybridization further localized pUNC724 to the pericentromeric region of the human acrocentrics. Two other EcoRI fragments that hybridized to pUNC724 were assigned to the long arms of chromosomes 1 and 18. The pUNC724 sequence does not appear to be related to ribosomal or satellite DNA sequences. The juxtaposition of DNA sequences homologous to pUNC724 and ribosomal DNA sequences presumably occurred within the past thirty-five million years, following the divergence of the lines leading to man and the New World owl monkey, Aotus trivirgatus--pUNC724 is not syntenic with the single chromosome containing ribosomal DNA sequences in the owl monkey.

Base Sequence↗
PubMed1984

Localization of the beta-globin gene by chromosomal in situ hybridization.

A 3.7-kilobase (kb) genomic clone of the human beta-globin gene, including 1.5-kb upstream and approximately 0.5-kb downstream, was utilized in chromosomal in situ hybridization for precise mapping of the beta-globin locus on peripheral blood lymphocyte-derived metaphases from a normal male, and for further evaluation of a clonal t(7;11) (q22;p15) translocation on bone marrow-derived metaphases from a 46-year-old male with erythroleukemia. Analyses of 205 midmetaphases from a normal male hybridized with the tritium-labeled beta-globin probe and stained with quinacrine mustard dihydrochloride revealed approximately 12% of spreads to have silver-grain deposition over the p15 band of chromosome 11. Of the 365 silver grains observed to be located on or beside chromosomes, 25 (approximately 7%) grains were localized in band p15. Karyotype analysis of a bone marrow specimen from the patient with erythroleukemia revealed hypodiploidy with various unidentified marker chromosomes as well as a presumably balanced translocation between 7q and 11p . Chromosomal in situ hybridization showed localization of silver grains at the junction between chromosomes 7 and 11 as well as to the normal chromosome 11, indicating that the beta-globin locus had not been translocated in the chromosomal rearrangement. This case demonstrates the value of chromosomal in situ hybridization in the definition of chromosome rearrangements and provides further evidence for the localization of the beta-globin gene to 11p15 .

Chromosome Banding↗
PubMed1984

Molecular genetic approaches to human diseases involving mental retardation.

Recombinant DNA techniques provide new approaches to the diagnosis and analysis of inherited human diseases associated with mental retardation. Examples of such diseases include the Lesch-Nyhan syndrome, phenylketonuria, the Fragile X syndrome, Down syndrome, and those associated with deletions or duplications of subchromosomal regions, e.g., the proximal short arm of human chromosome #15. For a limited but increasing number of diseases, the DNA sequences responsible for the phenotype (e.g., sequences coding for abnormal proteins) can be isolated directly. In many other cases, DNA segments mapping near genes responsible for diseases of interest can be isolated, e.g., from recombinant phage libraries enriched for specific regions of the genome by metaphase chromosome flow-sorting and then used in molecular linkage studies to "track" the abnormal gene in a pedigree. Both the necessary technology and the methods for its application continue to improve, and the impact of recombinant DNA studies in the field of mental retardation should increase markedly in the very near future.

Animals↗
PubMed1983

Stain intensity of human nucleolus organizer region reflects incorporation of uridine into mature ribosomal RNA.

The stain intensity of the nucleolus organizer regions (NORs) of acrocentric chromosomes was correlated positively with incorporation of [3H]uridine into 18S rRNA and 28S rRNA from cultured diploid human skin fibroblasts. An analysis of these data from twins by a path model indicated that no other common genetic or environmental parameters were required to explain the relationship between NOR scores and uptake of [3H]uridine into mature rRNA species.

Adolescent↗
PubMed1981

Genetic studies of an acardiac monster: evidence of polar body twinning in man.

Two maternally derived chromosome sets and both maternal histocompatibility antigen haplotypes were identified in the tissues of a malformed triploid acardiac twin that developed within the same chorion as its normal twin. These findings indicate that the twins arose as a result of independent fertilizations, by two different spermatozoa, of a normal haploid ovum and its diploid first-meiotic-division polar body.

Abnormalities, Severe Teratoid↗
PubMed1981

Spondylocostal dysostosis associated with anal and urogenital anomalies in a Mennonite sibship.

Spondylocostal dysostosis, anal atresia, and urogenital anomalies were observed in two male infants of a consanguineous Mennonite couple. A careful review of previously reported syndromes of severe vertebral abnormalities and/or imperforate anus suggests that our patients have a previously undescribed recessive disorder that should be included in the differential diagnosis of rib and vertebral anomaly syndromes.

Anus, Imperforate↗
PubMed1981

Quinacrine mustard and nucleolar organizer region heteromorphisms in twins.

Patterns of NOR activity in 640 metaphase spreads from twelve monozygotic (MZ) and eight dizygotic (DZ) twin pairs were studied to evaluate the heritability of this chromosomal heteromorphism. NORs were stained by a modification of the Ag-AS technique and counterstained with quinacrine mustard dihydrochloride to facilitate chromosome identification and assess their value in zygosity determination. In this study, all karyotypes were read blind with respect to zygosity and pair membership. A discriminant function analysis of pair score differences in MZ and DZ twins revealed that, in our sample, the probability of accurately determining zygosity with NOR scores was 0.93 and with QFQ scores was 0.99. We conclude that NOR and QFQ scores are highly heritable and of great value in zygosity determination. Data were collected from 687 metaphase spreads on the frequency with which an acrocentric chromosome was found in a satellite association. A significant correlation was found between this frequency and the degree of Ag-AS stain of the NOR. This study, therefore, confirms previous results showing that a high degree of NOR activity is found in those chromosomes most often involved in satellite associations.

Adolescent↗
PubMed1981

A genetic analysis of taste threshold for phenylthiocarbamide.

Taste threshold for phenylthiocarbamide (PTC) was measured in 393 offspring from the families of 85 monozygotic (MZ) twin pairs. PTC scores were bimodally distributed with modes at one and eight and the antimode at five. Because of the non-normality of the distribution, a jackknife procedure was used to obtain 95% confidence intervals for the estimates of genetic, maternal, and environmental parameters. Analyses which assumed no epistasis and which included additive genetic effects revealed that 37.9% of the observed variation in PTC threshold was due to additive genetic effects, 16.6% was due to dominance effects, 14.2% was due to maternal effects, 13.7% was due to a common sibship environment, and 17.6% was due to random environmental effects, yielding a broad sense heritability of 0.55 for the threshold ability to taste PTC. Analyses which did not include additive genetic effects revealed 26.6% of the observed variance was due to dominance effects, 23.6% to maternal effects, and 49.8% to environmental effects at the 0.67 confidence levels, but that environmental factors accounted for 72.4% and dominance effects for 23.6% of the observed variation at the 95% level.

Adolescent↗
PubMedDate not supplied

Human gamma-chain genes are rearranged in leukaemic T cells and map to the short arm of chromosome 7.

Three gene families that rearrange during the somatic development of T cells have been identified in the murine genome. Two of these gene families (alpha and beta) encode subunits of the antigen-specific T-cell receptor and are also present in the human genome. The third gene family, designated here as the gamma-chain gene family, is rearranged in murine cytolytic T cells but not in most helper T cells. Here we present evidence that the human genome also contains gamma-chain genes that undergo somatic rearrangement in leukaemia-derived T cells. Murine gamma-chain genes appear to be encoded in gene segments that are analogous to the immunoglobulin gene variable, constant and joining segments. There are two closely related constant-region gene segments in the human genome. One of the constant-region genes is deleted in all three T-cell leukaemias that we have studied. The two constant-region gamma-chain genes reside on the short arm of chromosome 7 (7p15); this region is involved in chromosomal rearrangements identified in T cells from individuals with the immunodeficiency syndrome ataxia telangiectasia and observed only rarely in routine cytogenetic analyses of normal individuals. This region is also a secondary site of beta-chain gene hybridization.

Amino Acid Sequence↗
PubMedDate not supplied

Leiomyomata: heritability and cytogenetic studies.

Leiomyomata represent the most common gynaecological tumour in women of reproductive age, and are the primary indication for hysterectomy in the USA. Cytogenetic and genetic studies have, in recent years, advanced our understanding of the aetiology of these tumours. Cytogenetic aberrations involving chromosomes 6, 7, 12 and 14 constitute the major chromosomal abnormalities seen in leiomyomata, and suggest the possibility that disruption or dysregulation of the genes HMGIC and HMGIY may contribute to the development of these tumours. Based on the finding of a variety of chromosomal aberrations detected in fibroids, other genes with fundamental roles in the pathobiology of uterine leiomyomata await identification. Furthermore, the incidence of fibroids has been shown to be greater in African-American women than in Caucasian women. The existence of a heritability component of uterine leiomyomata has been further implicated by twin-pair studies and the existence of familial forms of leiomyomata, both of which suggest an inherited diathesis for leiomyomata formation. This paper will review the cytogenetic aberrations and gene expression, with respect to their contributions to the pathogenesis of leiomyomata, and also summarize the current understanding of heritability of these tumours.

Black People↗
PubMedDate not supplied

A new age in the genetics of deafness.

Recent advancements have been made in understanding, diagnosing, and treating deafness. In particular, much has been learned from the discovery of a small fraction of the genes responsible for deafness. This understanding will doubtless increase as additional genes are cloned and their functions elucidated. Trailing close behind these achievements will be more clinical advancements facilitating diagnosis of the etiologies of deafness. Integrating these genetic and clinical perspectives is critical to the development of better treatments and interventional strategies for deafness and its associated difficulties. Although opinions toward these advancements are likely to vary between the hearing population and the Deaf community, a growing understanding of the hearing process and how genetic variations result in deafness is ultimately likely to offer benefits to both groups.

Deafness↗