21 Hydroxylase Deficiency
Mostrando 25-36 de 62 artigos, teses e dissertações.
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25. Nonsense mutation causing steroid 21-hydroxylase deficiency.
We determined the sequence of a mutant CYP21B gene isolated from a patient with the severe, "salt-wasting" form of congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency. Codon 318 in this gene is changed from CAG, encoding glutamine, to TAG, a nonsense codon. This is predicted to result in a completely nonfunctional enzyme due to premature
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26. Heterogeneity in the gene locus for steroid 21-hydroxylase deficiency.
DNA was analysed from 33 patients with congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency. In each case Southern blots were prepared from a number of restriction enzyme digests and hybridised with probes for both the 21-hydroxylase and the adjacent fourth component of complement (C4). Evidence for deletion of the active 21-hydroxylase ge
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27. Haplotypes of the steroid 21-hydroxylase gene region encoding mild steroid 21-hydroxylase deficiency.
Haplotypes of the complement 4 (C4) and steroid 21-hydroxylase [21-OHase; steroid hydrogen-donor: oxygen oxidoreductase (21-hydroxylating), EC 1.14.99.10] repeated gene complex were studied in nine families with at least one member affected with a mild form of 21-OHase deficiency. DNA probes from different parts of the repeated C4/21-OHase unit were used to
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28. Deletion of the steroid 21-hydroxylase and complement C4 genes in congenital adrenal hyperplasia.
DNA was analysed from 20 patients with congenital adrenal hyperplasia due to cytochrome P-450 steroid 21-hydroxylase deficiency. Using probes recognising sequences in both the 21-hydroxylase gene and the adjacent fourth component of complement (C4), one patient was found to have a homozygous deletion of DNA which encompassed the C4B and 21-hydroxylase B gene
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29. Genesis by meiotic unequal crossover of a de novo deletion that contributes to steroid 21-hydroxylase deficiency.
The HLA-linked human steroid 21-hydroxylase gene CYP21B and its closely homologous pseudogene CYP21A are each normally located centromeric to a fourth component of complement (C4) gene, C4B and C4A, respectively, in an organization suggesting tandem duplication of a ca. 30-kilobase DNA unit containing a CYP21 gene and a C4 gene. Such an organization has been
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30. Urinary excretion of pregnanetriol and Δ5-pregnenetriol in two forms of congenital adrenal hyperplasia
Although congenital adrenal hyperplasia due to 3β-hydroxysteroid dehydrogenase deficiency generally reveals a predominance of Δ5-3β-hydroxysteroids, on occasion substantial quantities of pregnanetriol have been found as well. It appears that the latter steroid more often occurs in the subjects who have survived beyond infancy. The use of the measurement o
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31. Presentation, acute illness, and learning difficulties in salt wasting 21-hydroxylase deficiency.
The presentation, pattern of acute illness, and incidence of learning difficulties are described in 63 (33 boys, 30 girls) children with salt wasting 21-hydroxylase deficiency, drawn from a cohort study of congenital adrenal hyperplasia in the South West Region of England between 1968 and 1988. Thirty boys presented with a salt losing crisis from birth where
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32. Disease expression and molecular genotype in congenital adrenal hyperplasia due to 21-hydroxylase deficiency.
Genotyping for 10 mutations in the CYP21 gene was performed in 88 families with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Southern blot analysis was used to detect CYP21 deletions or large gene conversions, and allele-specific hybridizations were performed with DNA amplified by the polymerase chain reaction to detect smaller mutations.
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33. Pulsed field gel electrophoresis identifies a high degree of variability in the number of tandem 21-hydroxylase and complement C4 gene repeats in 21-hydroxylase deficiency haplotypes.
The human steroid 21-hydroxylase gene, CYP21B, and its closely homologous pseudogene, CYP21A, are each normally located centromeric to a complement C4 gene C4B and C4A respectively, in an organization suggesting tandem duplication of a CYP21 + C4 unit. Such an organization has been considered to facilitate gene deletion and addition events by unequal crossov
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34. Characterization of frequent deletions causing steroid 21-hydroxylase deficiency.
Steroid 21-hydroxylase deficiency is caused by mutations in the CYP21B gene. This gene and a highly homologous pseudogene, CYP21A, alternate with the C4A and C4B genes encoding the fourth component of complement. Classical deficiency alleles are frequently caused by deletions of CYP21B or by gene conversions that transfer deleterious mutations from the CYP21
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35. Mutation in the CYP21B gene (Ile-172----Asn) causes steroid 21-hydroxylase deficiency.
Steroid 21-hydroxylase deficiency is the most common cause of congenital adrenal hyperplasia. It results from a deficiency in a specific cytochrome P450, P450c21 (P450XXIA). The gene encoding this protein (CYP21B) and a closely linked pseudogene (CYP21A) are located in the HLA complex on chromosome 6p. Many mutant alleles are associated with deletions of CYP
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36. Assessment of the one hour adrenocorticotrophic hormone test in the diagnosis of attenuated 21-hydroxylase deficiency.
Attenuated or partial 21-hydroxylase deficiency is one of several biochemical defects in steroid metabolism that can lead to hirsutism in young women after puberty. The diagnosis is made through the exaggerated response of 17 alpha-hydroxyprogesterone (17-OH) to adrenocorticotrophic hormone (ACTH). To provide reference data 72 mild to moderately hirsute pati