Cobalamin must be metabolized intracellularly in order to bind two enzymes: methionine synthase in cytoplasm and methylmalonyl-CoA mutase in mitochondria. Defects in this process cause different inborn errors of cobalamin metabolism (cblA-cblG and mut). A previous study described a cobalamin-binding protein, in addition to methylmalonyl-CoA mutase, in crude mitochondrial fractions. The amount of [57Co]cobalamin bound to this protein was increased in cblB, mut and cblD variant2 cell lines, compared to control cell lines. In the present study, this protein was identified as transcobalamin (TC). Mitochondrial fractions from a cblB cell line were incubated with anti-TC antibodies, which precipitated the cobalamin-bound protein. Analysis of mitochondrial and cytoplasmic fractions isolated from a chloroquine-incubated cblF cell line showed that isolated mitochondrial fractions contain lysosomal material, suggesting that the identified TC is lysosomal. Quantification of cobalamin-bound TC levels in whole cell extracts showed significant increases in cblB and mut groups compared to control cell lines.

Denaturing gradient gel electrophoresis (DGGE) and sequencing of the PAH locus has found 38 different mutations on 141 chromosomes in the PKU patients resident in Quebec; mutation analysis is now 92.5% complete. Two novel disease producing alleles (K421, R157N) and one silent allele (IVS6 nt-55) were discovered in this project; these mutations remain unique to the Quebec population. Three novel mutation-(haplotype) combinations were also found (S67P (H1), G218V (H2), V245A (H7)); they are not at hypermutable sites and are therefore compatible with a single homologous recombination event between two different haplotypes. Whereas mutation types (missense 64%, nonsense 6%, splice 9%, frameshifts 6%, silent 15%), resemble those in world populations, the Quebec allele profile differs from that of any European population, reflecting range expansion, founder effects, genetic drift and assimilation. Furthermore, when analyzed by geographic region a stratification of PAH alleles is apparent, reflecting the different demographic histories of Western and Eastern Quebec and Montreal.

Thesis (Ph.D. in Human Medical Genetics) -- University of Colorado at Denver and Health Sciences Center, 2006. / Typescript. Includes bibliographical references (leaves 127-143). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 5 uppsatser.

Thesis (Ph. D.)--University of Adelaide, Dept. of Paediatrics, 1991. / Copies of author's previously published articles inserted. Includes bibliographical references.

Thesis (Ph.D.)-- University of Adelaide, Dept. of Paediatrics, 2001. / Addendum inserted at back. Includes bibliographical references (leaves 266-287).

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