Methylmalonic aciduria is an autosomal recessive metabolic disorder, which may be due to a defect in the methylmalonyl CoA mutase (MCM) apoenzyme. The mut$ sp circ$ mutation is characterized by undetectable enzyme activity in cell extracts, and by the low incorporation of ($ sp{14}$C) propionate in the presence of hydroxocobalamin in culture. A mut$ sp circ$ fibroblast cell line, WG 1681, from an African-American male infant was shown to complement another mut$ sp circ$ cell line, WG 1130. Subsequent cloning and sequencing of cDNA from WG 1681 identified two previously described homozygous polymorphisms: H532R and V671I(1). In addition, compound heterozygosity was observed for two novel changes at highly conserved sites: G623R and G703R. Hybridization of allele specific oligonucleotides to PCR amplified MCM exons from WG 1681 and family members identified a clinically normal mother, sister and half-brother as carriers of the G703R change in cis with both polymorphisms. The putative father was not identified as a carrier of the G623R change. transfection of each change, singly and in cis with both polymorphisms, into GM1673 cells demonstrated a lack of stimulation of ($ sp{14}$C) propionate uptake in the absence and presence of OH-Cbl, in comparison to controls. Co-transfection of each separate mutation with the previously identified R93H mutation of WG 1130 (2) stimulated propionate uptake. These results indicate that G623R and G703R are novel mutations responsible for deficient MCM activity and the mut$ sp circ$ phenotype in WG 1681, and both mutations are independently capable of complementing the R93H mutation of WG 1130.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.69686 |
| Date | January 1993 |
| Creators | Qureshi, Amber A. (Amber Ateef) |
| Contributors | Rosenblatt, David S. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001358215, proquestno: AAIMM91784, Theses scanned by UMI/ProQuest. |
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