Exon 7 Nco l Restriction Site within CYP21B (Steroid 21-Hydroxylase) Is a Normal Polymorphism (original) (raw)
Related papers
Human Molecular Genetics, 1996
Steroid 21-hydroxylase deficiency is among the most common inborn errors of metabolism in man. Characterization of mutations in the 21-hydroxylase gene (CYP21) has permitted genetic diagnosis, facilitated by the polymerase chain reaction (PCR). The most common mutation is conversion of an A or C at nt656 to a G in the second intron causing aberrant splicing of mRNA. Homozygosity for nt656G is associated with profoundly deficient adrenal cortisol and aldosterone synthesis, secondary hypersecretion of adrenal androgens, and a severe form of congenital adrenal hyperplasia (CAH) characterized by ambiguous genitalia and/or sodium wasting in newborns. During the course of genetic analysis of CYP21 mutations in CAH families, we and others have noticed a number of relatives genotyped as nt656G homozygotes, yet showing no clinical signs of disease. A number of lines of evidence have led us to propose that the putative asymptomatic nt656G/G individuals are incorrectly typed due to dropout of one haplotype during PCR amplification of CYP21. For prenatal diagnosis, we recommend that microsatellite typing be used as a supplement to CYP21 genotyping in order to resolve ambiguities at nt656.
Hormone Research, 2000
Molecular defects in the gene encoding steroid 21hydroxylase (CYP21) result in impairment of adrenal steroid synthesis in patients affected with autosomal-recessive congenital adrenal hyperplasias (CAH). In this study, we report on the molecular screening of six point mutations, large deletions, gene conversion events and duplications in 25 unrelated Lebanese families affected by CAH due to steroid 21-hydroxylase. The methods used (PCR-digestion and southern blot) allowed the detection of 96% of the disease chromosomes. In classical forms, the most frequent mutation was the splice site mutation in intron 2 accounting for 39% of the disease alleles. Gene conversion events accounted for 14% of the alleles, but no large deletions were found. In nonclassical forms, the V281L mutation in exon 7 represent 86% of the tested alleles. Genotype-phenotype correlations were as expected: ¢8nt, Q318X and gene conversion correspond to SW forms, whereas the intron 2 splice site mutation may give either SW or SV forms; the V281L mutation was responsible for nonclassical forms. The spectrum of mutations underlines the genetic diversity of the Lebanese population. No correlation could be drawn out between mutations and some specific religious communities, except for the ¢8nt mutation, which is present only in the Christian Maronite group. Molecular study of the CYP21 gene might constitute a good support for clinicians, especially in consanguineous families, for whom we could provide genetic counselling.
American journal of human genetics, 1989
The gene CYP21B, encoding the steroid 21-hydroxylase enzyme of adrenal steroid biosynthesis, has been mapped to the human major histocompatibility complex (MHC). Deficiency of this enzyme leads to congenital adrenal hyperplasia (CAH). We report the phenotypes of the HLA and complement C4 and Bf genes, which are closely linked to the CYP21B gene, together with a detailed analysis of the CYP21 and C4 RFLP, in 17 Finnish families with CAH. The RFLP analysis with six restriction enzymes suggested that, altogether, 35% of the affected chromosomes had a CYP21B + C4B gene deletion, 9% an obvious gene conversion of the CYP21B gene to a CYP21A-like gene, and 3% a CYP21A + C4B duplication. The remaining 53% gave the RFLP patterns also found in nonaffected chromosomes. We also found that a 14.0-kb EcoRI RFLP marker of the CYP21 genes was strongly associated with the presence of a short C4B gene, suggesting that some of the RFLP markers found with the CYP21 probe may actually derive from C4B ge...
Molecular Diagnosis & Therapy, 2018
Congenital adrenal hyperplasia (CAH) comprises a group of autosomal recessive disorders caused by complete or partial defects in one of the several steroidogenic enzymes involved in the synthesis of cortisol from cholesterol in the adrenal glands. More than 95-99% of all cases of CAH are caused by deficiency of steroid 21-hydroxylase, an enzyme encoded by the CYP21A2 gene. Currently, CYP21A2 genotyping is considered a valuable complement to biochemical investigations in the diagnosis of 21-hydroxylase deficiency. More than 200 mutations have been described in literature reports, and much energy is still focused on the clinical classification of new variants. In this review, we focus on molecular genetic features of 21-hydroxylase deficiency, performing an extensive survey of all clinical pathogenic variants modifying the whole sequence of the CYP21A2 gene. Our aim is to offer a very useful tool for clinical and genetic specialists in order to ease clinical diagnosis and genetic counseling. Key Points An extensive effort was made in order to collect literature data reporting CYP21A2 pathogenic variants. We were able to provide 233 pathogenic CYP21A2 variants and their clinical classification.
Clinical Chemistry and Laboratory Medicine, 2010
Congenital adrenal hyperplasia (CAH) is characterized by impaired biosynthesis of cortisol. 21hydroxylase deficiency is the most common cause of CAH affecting 1 in 10000-15000 live births over the world. The frequency of the disorder is very high in Iran due to frequent consanguineous marriages. Although biochemical tests are used to confirm the clinical diagnosis, molecular methods could help to define accurate diagnosis of the genetic defect. Recent molecular approaches such as polymerase chain reaction based methods could be used to detect carriers and identify different genotypes of the affected individuals in Iran which may cause variable degrees of clinical expression of the condition. Molecular tests are also applied for prenatal diagnosis, and genetic counseling of the affected families. Here, we are willing to delineate mechanisms underlying the disease, genetic causes of CAH, genetic approaches being used in the country and recommendations for health care improvement on the basis of the molecular and clinical genetics to control and diminish such a high prevalent disorder in Iran. Also, the previous studies on CAH in Iran are gathered and a diagnostic algorithm for the genetic causes is proposed.
BMC Medical Genetics, 2009
Background: More than 90% of Congenital Adrenal Hyperplasia (CAH) cases are associated with mutations in the 21-hydroxylase gene (CYP21A2) in the HLA class III area on the short arm of chromosome 6p21.3. In this region, a 30 kb deletion produces a non functional chimeric gene with its 5' and 3' ends corresponding to CYP21A1P pseudogene and CYP21A2, respectively. To date, five different CYP21A1P/CYP21A2 chimeric genes have been found and characterized in recent studies. In this paper, we describe a new CYP21A1P/CYP21A2 chimera (CH-6) found in an Italian CAH patient.
Phoenix Medical Journal, 2020
Congenital adrenal hyperplasia (CAH) belongs to the group of familial diseases with autosomal recessive inheritance, which is caused by a disorder of adrenal steroid production. It is caused by the deficiency of any of the five enzymes that provide cortisol synthesis from cholesterol in the adrenal cortex. Characteristic of CAH is ambiguous genital structure and impaired sexual development. The most common cause of CAH is 21-hydroxylase enzyme deficiency. The CAH, which is caused by 21-hydroxylase deficiency, has 2 types as 'classic' and 'non-classical'. The differences in the clinical picture depend on the structural and functional changes caused by mutations in the 21-hydroxylase gene. The two steroid 21-hydroxylase genes (CYP21A2 active gene, CYP21P pseudogene) are located on the short arm of chromosome 6. The mutations that cause defect of the active gene are due to the fact that active and pseudogene are very close and quite homologous. Deletions, duplications, gene conversions and point mutations occur as a result of intergenic recombination of the DNA sequence. Due to the presence of CYP21A2 pseudogene; there are often problems in diagnosing CAH, which develops due to 21-hydroxylase deficiency only with sequence analysis studies for the CYP21A2 gene.
A Novel 13-bp Deletion in Exon 1 of CYP21 Gene Causing Severe Congenital Adrenal Hyperplasia
Diagnostic Molecular Pathology, 2005
Congenital adrenal hyperplasia (CAH) is a common autosomal recessive disorder mainly caused by defects in the steroid 21-hydroxylase gene (CYP21). In most cases, this defect is the result of gene conversion events between the functional CYP21 gene and the adjacent inactive pseudogene (CYP21P). Previous screening for mutations of 21-hydroxylase gene in 51 unrelated Tunisian CAH patients revealed 4 novel mutations that have not been reported to occur in the CYP21P pseudogene. The present paper describes the fifth new small 13-bp deletion in exon 1 found after sequencing the CYP21 gene of a Tunisian patient suffering from the salt-wasting form of CAH. The patient is a girl born to consanguineous parents; she is homozygous for a novel deletion. The 13-bp deletion causes a stop codon at amino acid 47, which is likely to result in an enzyme with no activity. Both parents are heterozygous for the small deletion as confirmed by nested PCR method. This novel mutation has not been reported to occur in the CYP21P pseudogene, indicating a casual mutagenic event rather than a conversion one.
Brazilian Journal of Medical and Biological Research, 2003
Deficiency of 21-hydroxylase is the most common form of congenital adrenal hyperplasia (CAH-21OH). We determined by allele-specific PCR the frequency of microconversion in the CYP21A2 gene in 50 Brazilian patients with the classical (salt wasting: SW and simple virilizing: SV) forms and nonclassical (NC) form of CAH-21OH and correlated genotype with phenotype. Genotypes were classified into three mutation groups (A, B, and C) based on the amount of enzymatic activity in in vitro studies using adrenal cells. In 94 unrelated alleles, we diagnosed 76% of the affected alleles after screening for 7 microconversions. The most frequent point mutations observed in this series were I172N (19%), V281L (18%), and IVS2,A/C>G,-12 (15%). In the SW form, the most frequent mutation was IVS2,A/C>G,-12 (38%), in the SV form it was I172N (53%), and in the NC form it was V281L (57.7%). We observed a good correlation between genotype and phenotype. Discordance between genotype and phenotype was found in one SV patient with a mild mutation in one of the alleles (R356W/V281L). However, we cannot rule out the presence of an additional mutation in these alleles. We also observed a good correlation of genotype with 17α-hydroxyprogesterone, testosterone, and androstenedione levels. The severity of external genitalia virilization correlated with the severity of mutation. In conclusion, the frequencies described in the present study did not differ from worldwide studies, including the Brazilian population. The few differences observed may reflect individual sample variations. This new Brazilian cohort study suggests the presence of new mutations in Brazilian patients with different forms of CAH-21OH.
Rare mutations in the CYP21A2 gene detected in congenital adrenal hyperplasia
Clinical Biochemistry, 2009
The purpose of this study was to identify and determine the frequencies of rare CYP21A2 gene mutations in patients with 21-hydroxylase deficiency (21-OHD) in the Cypriot population.Direct sequencing and MLPA analysis of the CYP21A2 gene.A group of families with 21-OHD were screened for the presence of rare CYP21A2 gene mutations. The rare V304M missense mutation was detected as compound heterozygous in two females with the nonclassical (NC) form of congenital adrenal hyperplasia (CAH). The rare F306insT was also detected in a female with severe salt wasting in the homozygous state and in cis in both alleles with the V281L mutation. Lastly, the rare A391T missense mutation was reported in a female patient with NC-CAH. A carrier rate of 2.1% for the V304M was also observed in a cohort of healthy controls.The frequency of V304M mutation among Cypriots is high and the first reported so far and patients characterized as compound heterozygotes or heterozygotes are most readily identified by a mild phenotype of CAH. Thus, V304M should be included in the panel of mutations associated with the NC forms of 21-OHD.