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The use of chromosome aberrations in human gene mapping
Başlık:
The use of chromosome aberrations in human gene mapping
Yazar:
Aitken, David A., author.
ISBN:
9780438060609
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (250 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Advisors: M. A. Smith-Ferguson.
Özet:
The aim of this study was to exploit chromosome aberrations to provide gene mapping information which can be used to localise the chromosome positions of certain structural gene loci. Qualitative investigation of a number of autosomal gene loci coding for 24 polymorphic markers was performed by typing these markers in red cell and serum samples from chromosomally unbalanced individuals and their relatives. Malsegregation of the parental red cell adenylate kinase phenotypes was found in a one child with a structural aberration of chromosome 9, but did not indicate a chromosome assignment for this marker in this instance. Collation of data from these marker investigations in patients with deletions, and from similar cases reported in the literature has allowed the construction of an Exclusion Map which indicates certain regions of the chromosomes which do not carry particular structural genes. The MNSs blood group locus has been excluded from more than 30% of the total haploid autosomal length in this fashion. Quantitative investigations of four structural gene loci coding for the red cell enzymes adenylate kinase (AK-1), adenosine deaminase (ADA), nucleoside phosphorylase (NP), and glutamic oxaloacetic transaminase (GOTS), were performed by assay of these enzymes in appropriate blood samples. The chromosome location of each of these structural genes was previously known from other gene mapping investigations reported in the literature, and the quantitative assay of each enzyme was performed in red cell samples from patients whose chromosome complement was unbalanced with respect to the particular chromosome known to carry the structural gene. Red cell AK-1 assay was used in 10 patients with partial duplication or deletion of chromosome 9, and in one other patient with a structural aberration of chromosome 9, in an attempt to find the precise intrachromosomal location of the structural gene. All regions of chromosome 9 were represented in abnormal dosage in at least one patient. A 43% increase in AK-1 activity was found to "be associated with duplication of the proximal 2/3rds of the terminal band of the long arm of chromosome 9, all other regions being associated with normal enzyme activity, suggesting localisation of the AK-1 structural gene in this region. By virtue of their close linkage, the ABO blood group locus and Nail Patella (Np-1) locus can also be assigned to the same region at the distal end of the long arm of chromosome 9. An approximately 50% reduction in AK-1 activity was found in the case of the patient with the structural 9 aberration, and the significance of this result in relation to the phenotype of the patient and the suggested regional localisation of the AK-1 structural gene, is discussed. Red cell ADA activity was assayed in two patients with a deletion and one with a duplication of the same region of the short arm of chromosome 20. Normal enzyme activity in two chromosomally unbalanced individuals from the same family, one with a deletion and the other a duplication of the distal 2/3rds of the short arm of chromosome 20 suggest that the ADA locus can be excluded from this region and is therefore assigned to the long arm or the proximal 1/3rd of the short arm of chromosome 20. However, unexpectedly high ADA activity was found in the other patient with this deletion, his karyo-typically normal sister and in 3 control samples, and the validity of mapping the ADA locus on chromosome 20 by this method is discussed. An attempt to map the NP locus on chromosome 14 by quantitative assay of the enzyme in two patients with chromosome 14 aberrations has suggested that the locus can be excluded from the short arm and a small proximal region of the long arm of chromosome 14 by the demonstration of a normal enzyme activity associated with a deletion of this region. Combining this result with other published data concerning the regional location of the NP structural gene, suggests a tentative location for this locus between the two darkly staining proximal bands on the long arm of chromosome 14. Quantitative assay of red cell GOTS both with and without pyridoxal-5-phosphate cofactor has been used in two patients, one with a duplication of the distal 3 bands and the other with a deletion of the terminal band of the long arm of chromosome 10 in an attempt to unmask the GOTS structural locus position by demonstration of a s gene dosage effect. An approximate 50% increase in enzyme activity over the mean level ascertained in a phenotypically normal control group was found to be associated with duplication of the terminal 3 hands of chromosome 10. No corresponding reduction was found in the patient with the deletion, and the GOTS structural gene can thus he assigned to a discrete region on the long arm of chromosome 10. The use of chromosome aberrations in human gene mapping and the merits of gene dosage investigations by quantitative red cell enzyme assays are discussed.
Notlar:
School code: 0547
Tüzel Kişi Ek Girişi:
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(684829.1) | 684829-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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