To analyze the mutational spectrum of steroid 21-hydroxylase (CYP21) and the genotype- phenotype correlation in patients with congenital adrenal hyperplasia (CAH) registered in the Middle European Society for Pediatric Endocrinology CAH database, and to design a reliable and rational approach for CYP21 mutation detection in Middle European populations.
Molecular analysis of the CYP21 gene was performed in 432 CAH patients and 298 family members. Low-resolution genotyping was performed to detect the eight most common point mutations. High-resolution genotyping, including Southern blotting and sequencing was performed to detect CYP21 gene deletions, conversions, point mutations or other sequence changes.
CYP21 gene deletion and In2 and Ile172Asn mutation accounted for 72.7% of the affected alleles in the whole study group. A good genotype-phenotype correlation was observed, with the exception of Ile172Asn and Pro30Leu mutations. In 37% of patients low resolution genotyping could not identify the causative mutation or distinguish homozygosity from hemizygosity. Using high-resolution genotyping, the causative mutations could be identified in 341 out of 348 analyzed patients. A novel mutation Gln315Stop was found in one simple virilising CAH (SV-CAH) patient from Austria. In the remaining seven patients polymorphisms were identified as the leading sequence alteration. The presence of elevated basal and ACTH-stimulated 17-hydroxyprogesterone, premature pubarche, advanced bone age and clitoral hypertrophy directly implicated Asn493Ser polymorphism in the manifestation of nonclassical- (NC) and even SV-CAH.
By genotyping for the most common point mutations, CYP21 gene deletion/conversion and the 8 bp deletion in exon 3, it should be possible to identify the mutation in 94-99% of the diseased alleles in any investigated Middle European population. In patients with a mild form of the disease and no detectable mutation CYP21 gene polymorphisms should be considered as a plausible disease-causing mutation.
"The incidence of classical CAH is 1:30,000, which is much less than expected compared with other Mediterranean countries (Forest, 2004; van der Kamp and Wit, 2004; Merke and Bornstein, 2005). We have recently reported that IVS2-13A/C > G can be considered the most frequent molecular defect in the SW form, and its high frequency is consistent with most studies reported so far (Owerbach et al., 1992; Speiser et al., 1992; Ezquieta et al., 1995; Wilson et al., 1995a, 1995b; Carrera et al., 1996; Dardis et al., 1997; Jaaskelainen et al., 1997; Bachega et al., 1998; Fardella et al., 1998; Lako et al., 1999; Krone et al., 2000; Dracopoulou-Vabouli et al., 2001; Kotaska et al., 2003; Dolzan et al., 2005; Skordis et al., 2011a; Wilson et al., 1995b). Large lesions are quite rare in the Greek-Cypriot population and are less frequent than the ones observed either in the Hellenic population (14.3%) or in other ethnic groups (Carrera et al., 1996; Dardis et al., 1997; Fardella et al., 1998; Dracopoulou- Vabouli et al., 2001); this can be attributed to either differences in the genetic background or the poor number of patients screened (Skordis et al., 2011a). "
[Show abstract][Hide abstract] ABSTRACT: Aim:
Hereditary endocrinopathies in Cyprus exhibit evidence of a founder effect and display the influence of past migration patterns. The genetic frequency and mutation pattern of a specific disorder of sex development (DSD), which is classified as 46,XX DSD or 46,XY DSD, and the non-classic form of congenital adrenal hyperplasia (NC-CAH) outline a type of genetic drift.
Not only the high prevalence of the NC-CAH p.V281L mutation but also the rarity of CAH large lesions present a genetic diversity similar to that observed in the Middle Eastern countries. In addition, both the high frequency of the 5-alpha steroid reductase deficiency (5αSRD) IVS1-2A>G mutation and the carrier frequency of the 17-beta hydroxysteroid dehydrogenase 3 (17β-HSD-3) p.R80Q mutation are good examples of a founder effect. p.R80Q can be considered a founder mutation, even though it has been identified in patients of Dutch, Brazilian, and Portuguese origin. This has led to the speculation that it has a Phoenician origin. Phoenicians as ancient traders migrated around 750 BC from present day Syria, Lebanon, and Israel toward Portugal, Spain, and also to nearby Cyprus. While the 5αSRD IVS1-2A>G mutation has already been extensively reported in Turkish patients, it is very common in the Eastern Mediterranean region.
This short article portrays clearly, through specific endocrine genetic disorders, the past migration trends in Cyprus that shaped the present-day gene pool of the Greek-Cypriot population.
"I172N is the only one mutation specifically associated with the SV form of the disease, and mutation of this hydrophobic residue to a polar residue results in an enzyme with approximately 1% or normal activity. The frequency of p.P30L mutation was relatively high in our study, when compared with other studies. This mutation was first described in a nonclassic CAH patient and considered as a part of larger gene conversion or a chimeric CYP21A1P/CYP21A2 gene. "
[Show abstract][Hide abstract] ABSTRACT: Congenital adrenal hyperplasia (CAH) is one of the inborn errors of metabolic disorder inherited in an autosomal recessive manner caused by the defects in the steroid 21 hydroxylase CYP21A2 gene. We analyzed the genotype of 62 patients with classic CAH.
To find out the underlying mutations of CYP21A2 gene.
Cohort of CAH patients.
Sixty-two patients with CAH were recruited from the endocrine clinic at AIIMS. Electrochemiluminiscence method was used for estimating the levels of cortisol. Radioimmunoassay kit-based method was used for estimating the 17 OHP levels. Polymerase chain reaction amplification was done using specific primers to amply the CYP21A2 gene.
Statistical analysis was done by using Epi Info Version 22.214.171.1248.
Out of 62 patients, 50 were simple virilizers (SV) and 12 were salt wasters (SW). Fifty-six were females and six were males. Five 46, XX children were reared as males. Age at presentation varied from 8 months to 38 years. Molecular genetic analysis revealed that the highest number of patients harboured (In 2) IVS2-13 A/C > G (48%), followed by p.P30L (46%), p.Q318X (35%), (D 8 bp) deletion 8 bp (26%), p.I172N (26%), and p. R356W (20%) mutations.
This is among the few studies to analyze the mutational spectrum of CYP21A2 gene in a large CAH cohort from India. Molecular diagnosis of CYP21A2 gene should be considered as part of the CAH evaluation to assess the risk of the patients/parents/siblings and to offer genetic counseling.
"Similar findings were also reported by Krone et al. , where the prediction of genotype phenotype correlation in patients with the NC-CAH form was stronger when the p.P30L mutation was excluded . The presence of p.P30L was found in 23 out of 93 patients with the SV form either in homozygosity or in a compound heterozygote state with a second mutation or gene deletion/conversion . The diversity of the clinical phenotype in patients carrying the p.P30L mutation is further supported by its presence in patients with all forms of CAH . "
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to identify the molecular defect in a group of 37 unrelated Greek Cypriot patients affected by NC-CAH and evaluate the relationship between the genotype, phenotype and adrenal androgen levels.
Clinical evaluation, biochemical analysis of 17-OHP, Testosterone, Androstenedione, DHEA-S, direct DNA sequencing and MLPA analyses.
Eleven known mutations were identified with the p.V281L being the most predominant and observed in 68.9% of the alleles. There was no difference between the two genotypes (mild/mild and mild/severe) with clinical presentation, whereas a proportional relationship between the type of mutation and adrenal androgen levels was found.
The frequency of the underlying genetic defect in our patients with NC-CAH is similar to that observed in most Mediterranean populations. Although the genotype cannot solely explain the clinical expression of NC-CAH, discrimination between mild and severe alleles is crucial in antenatal diagnosis and genetic counselling.
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