1/9. Combined 17alpha-Hydroxylase/17,20-lyase deficiency caused by Phe93Cys mutation in the CYP17 gene.Seventeen alpha-hydroxylase/17,20-lyase deficiency is a rare, autosomal recessive form of congenital adrenal hyperplasia not linked to human leukocyte antigen and characterized by the coexistence of hypertension caused by the hyperproduction of mineralocorticoid precursors and sexual abnormalities, such as male pseudohermaphroditism and sexual infantilism in female, due to impaired production of sex hormones. Both 17alpha-hydroxylase and 17,20-lyase reactions are catalyzed by a single polypeptide, cytochrome P450c17 (CYP17), which is encoded by the CYP17 gene located on chromosome 10q24-q25. Mutations in the CYP17 gene have been recognized to cause the 17alpha-hydroxylase/17,20-lyase deficiency syndrome. Here, we describe two phenotypically and hormonally affected Italian patients with 17alpha-hydroxylase/17,20-lyase deficiency. The family history revealed consanguinity of the parents. Linkage and haplotype analyses using microsatellites on chromosome 10q24-q25 demonstrated that the two affected individuals were homozygous at these loci. The mutation screening of the CYP17 gene identified a new Phe93Cys missense mutation in exon 1. The amino acid substitution is located in a highly conserved region of the protein and is not a polymorphism because it is not present in one hundred normal alleles. in vitro functional studies showed that the Phe93Cys mutated CYP17 retains only 10% of both 17alphahydroxylase and 17,20-lyase activities, according to the severe phenotype. Our results shed more light on the structure-function relationship of the CYP17 protein indicating that Phe 93 is crucial for both enzymatic activities.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
2/9. Congenital 21-hydroxylase deficiency as a new deletion mutation. Detection in a proband during subsequent prenatal diagnosis by HLA typing and dna analysis.A child with 21-OH-def whose 9 weeks' pregnant mother was referred for prenatal diagnosis was found upon very careful histocompatibility testing to lack expression of any of his father's hla antigens on his peripheral blood lymphocytes. The possibility of alternative paternity was considered to be extremely unlikely after additional genetic marker tests. The conclusion that the affected child's disease resulted from inheritance of a maternal CYP21B (21-OH) deletion and a de novo deletion in the paternal chromosome 6 segment that includes both the CYP21B (21-OH) and HLA genes was confirmed by subsequent dna analysis using 21-OH, C4, DPB, and PCH6 probes. The presence of a heterozygous RFLP for DPB, the absence of a deletion for either CYP21B (21-OH) or C4 genes, and the presence of a paternal HLA antigen haplotype on the fetal cells additionally indicated that the fetus lacked the same deletion and could be predicted to be completely normal.- - - - - - - - - - ranking = 2keywords = antigen (Clic here for more details about this article) |
3/9. Deletion within the CYP17 gene together with insertion of foreign dna is the cause of combined complete 17 alpha-hydroxylase/17,20-lyase deficiency in an Italian patient.The molecular basis of 17 alpha-hydroxylase/17,20-lyase deficiency syndrome in a 14-yr-old 46,XY Italian patient was investigated by amplification, subcloning, and sequencing of specific exonic sequences from genomic dna samples. A homozygous mutation, consisting of a 518-basepair (bp) deletion combined with a 469-bp insertion, was identified in the CYP17 gene of the patient. The deletion spans much of exon II, the whole intron 2, and a portion of exon III. A part (156 bp) of the inserted sequence shows 95.5% identity to the nuclear antigen-binding site on marek disease virus dna and sequences found in rearranged mitochondrial dna of rat hepatoma cells. A similar degree of sequence identity (99%) was also found between the above sequences and part of the lac operon of E. coli. The inserted sequence is lacking the BamHI site in intron 2 of CYP17 and contains an in-frame stop codon (TAA). Thus, the mutated gene encodes a truncated nonfunctional steroid hydroxylase, giving rise to symptoms associated with complete combined 17 alpha-hydroxylase/17,20-lyase deficiency. The family history revealed that the patient is the child of a consanguineous marriage and has two genotypically and phenotypically female sisters also suffering from symptoms of the disease. Investigation of genomic dna from these sisters revealed that in each case both CYP17 alleles contained the same mutation. On the other hand, the parents were found to be heterozygous for this mutation. The insertion could not be found in dna from normal individuals or in the CYP17 gene of other Italian patients with the 17 alpha-hydroxylase deficiency syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
4/9. Divergent phenotype of two siblings human leukocyte antigen identical, affected by nonclassical and classical congenital adrenal hyperplasia caused by 21-hydroxylase deficiency.CONTEXT: Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders most often caused by enzyme 21-hydroxylase deficiency. Most mutations causing enzymatic deficiency are generated by recombinations between the active gene CYP21 and the pseudogene CYP21P. Only 1-2% of affected alleles result from spontaneous mutations. The phenotype of CAH varies greatly, usually classified as classical or nonclassical, depending on variable degree in 21-hydroxylase activity. Here we report a divergent phenotype of two human leukocyte antigen identical siblings, affected by nonclassical and classical CAH caused by 21-hydroxylase deficiency due to different genotype. patients AND methods: Using direct sequencing method and Southern blot, we studied two children (one male and one female), affected, respectively, by nonclassical and classical CAH and their parents. RESULTS: The mother was heterozygous for the Q318X mutation, and the father was heterozygous for the V281L mutation. The brother was a compound heterozygote for the mutations V281L and Q318X, whereas the proband was compound heterozygote for the Q318X mutation and a large conversion. The two children are human leukocyte antigen identical (A*02;B*14;DRB1*01/A*33;B*14;DRB1*03). CONCLUSIONS: Different phenotype of the proband is the result of compound heterozygosity for the maternal mutation Q318X and a de novo large conversion.- - - - - - - - - - ranking = 6keywords = antigen (Clic here for more details about this article) |
5/9. Gene conversions and rearrangements cause discordance between inheritance of forms of 21-hydroxylase deficiency and HLA types.Congenital adrenal hyperplasia (CAH) can be caused by a variety of defects in the functional gene encoding 21-hydroxylase (P450c21), which lies in the midst of the human leukocyte antigen (HLA) locus on chromosome 6. As a result, Mendelian genetics permit clinically distinct forms of CAH to be traced genetically by HLA and complement typing of family members. The recent cloning of probes for P450c21 now permits tracing of the affected gene directly. A consanguineous family had three members affected with three clinically distinct forms of CAH. Two of these individuals had identical extended haplotypes, including nine HLA and complement loci. Despite this extensive identity, the patterns of genomic dna fragments digested with endonuclease EcoRI and detected by a P450c21 cDNA probe differed greatly in these two individuals. Thus, the dna diagnosis of allelic variation was much more sensitive than the HLA diagnosis. Genomic dna digested with endonuclease TaqI and probed with P450c21 cDNA revealed the 3.2-kilobase (kb) band, which is generally associated with the nonfunctional P450c21 A pseudogene, in all family members, and also revealed the 3.7-kb band associated with the functional P450c21 B gene in all family members except the severely affected index case. Probing of the same blots with a genomic probe also permitted examination of the adjacent downstream TaqI fragments, showing retention of both the 2.4-kb (A pseudogene) and 2.5-kb (B gene) fragments. Similarly, BglII-digested genomic dna from all individuals contained both the 12-kb (A pseudogene) and 11-kb (B gene) bands. These data indicate that the basis of 21-hydroxylase deficiency in the index case was due to a homozygous gene conversion event and not to gene deletion. These results show that the dna in and around the 21-hydroxylase gene is genetically very active, so that the usual generalization concerning linkage and inheritance may yield incorrect conclusions and diagnoses.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
6/9. adult-onset familial adrenal 21-hydroxylase deficiency.Two sisters (28 and 30 years) were investigated for primary infertility and milk hirsutism. Both had normal puberty, were having regular menses and had normal female sexual characteristics. Studies revealed elevated urinary 17-ketosteroid levels (15.8, 18.8 mg/24 hours) and increased serum levels of 17-OH-progesterone (2,756, 1,121 ng/dl), 21-desoxycortisol (1,882, 1,090 ng/dl), progesterone (300, 346 ng/dl), dehydroepiandrosterone (DHA) (1,600, 1,700 ng/dl), and androstenedione (402, 366 ng/dl) and testosterone (100, 104 ng/dl), together with a slight increase in serum 11-desoxycortisol (1,180, 1,560 ng/dl). blood pressure, serum sodium/potassium plasma renin and serum aldosterone, corticosterone, 11-desoxycorticosterone and cortisol levels were normal. The administration of ACTH caused a further increase in 21-hydroxylase precursors; the administration of dexamethasone normalized hormone levels and produced ovulatory cycles. Similar studies in two siblings were normal. The affected sisters were HLA identical and did not share any hla antigens with their healthy siblings. The data suggest that these patients have a mild form of 21-hydroxylase deficiency which was insufficient to cause prenatal virilization. The gene for this disorder may be allelic with that for typical congenital adrenal hyperplasia.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
7/9. Late-onset type of 21-hydroxylase deficiency in childhood.It was recently proposed that congenital and late-onset 21-hydroxylase deficiency are caused by two distinct recessive allelic genes. Although both genes are associated with the HLA system, only the late-onset type was found to be linked with the antigens B14 and DR1. Biochemical and immunological studies were conducted in two families with children suffering from 21-hydroxylase deficiency of postnatal onset. In the first family, of Jewish Ashkenazic origin, a 2 1/2-yr-old girl presenting with clitoromegaly was found to be homozygous for the antigens B14 and DR1. In the second family, of Arabic origin, all the children, their parents and a paternal aunt were clinically and/or biochemically affected, carrying the B14, but not the DR1 antigen on one or both HLA haplotypes. These data suggest that some cases of simple virilizing 21-hydroxylase deficiency in childhood are related to the late-onset type of 21-hydroxylase deficiency.- - - - - - - - - - ranking = 3keywords = antigen (Clic here for more details about this article) |
8/9. Concordance of 21-hydroxylase gene ratio, human leukocyte antigen haplotyping and adrenal testing results in a family with late-onset adrenal hyperplasia.Late-onset adrenal hyperplasia (LOAH) due to 21-hydroxylase (21-OH) deficiency is one of the most common autosomal recessive disorders. There appear to be two 21-OH genes, CYP21A (a pseudogene) and CYP21B (the functional gene), which lie in close proximity to the human leukocyte antigen (HLA) encoding region on the short arm of chromosome 6. While the CYP21A/CYP21B ratio is normally 1:1, ratio abnormalities are frequent in LOAH, suggesting gene deletion, duplication or conversion. The objective of this study was to determine whether an abnormal CYP21A/CYP21B ratio could predict carriers of LOAH, as determined by endocrine and HLA results. The probands appear to be compound heterozygotes carrying a 21-OH gene for LOAH and a deletion of the homologous gene. However, concordance between an abnormal 21-OH gene ratio and the inheritance of the LOAH gene does not appear to be complete, as demonstrated by this family study. Further studies of the feasibility of screening carriers for 21-OH deficiencies with the CYP21A/CYP21B ratio or other molecular probes must be performed.- - - - - - - - - - ranking = 5keywords = antigen (Clic here for more details about this article) |
9/9. female pseudohermaphroditism due to congenital adrenal hyperplasia complicated by adenocarcinoma of the prostate and clear cell carcinoma of the endometrium.The presence of prostatic glandular tissue in female pseudohermaphrodites has previously been documented. However, prostatic neoplasia in this clinical setting has not been reported. A karyotypic female with congenital adrenal hyperplasia due to 21-hydroxylase deficiency developed a prostatic adenocarcinoma associated with elevated serum prostatic specific antigen levels and osteoblastic skeletal metastases. This demonstrates that this tissue in pseudohermaphrodites can become malignant. In addition, the patient subsequently developed clear cell carcinoma of the endometrium, possibly related to radiation therapy for the prostatic adenocarcinoma. This demonstrates that female pseudohermaphrodites may be at risk not only for malignancies seen in genotypic females but also prostate cancer.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |