Total DNA isolated from the peripheral blood of the two probands was screened for potential mutations in the following susceptibility genes of CAH: CYP21A2, CYP11B1, CYP17A1, HSD17B3, HSD3B2, ARMC5, and STAR using Target Capture-Based Deep Sequencing; and Sanger sequencing was conducted for the family members to detect the potential mutations.
Sequencing of the AR gene in five unrelated CAH girls with the I172N mutation in CYP21 and minimal virilization did not reveal any additional deviations from the normal reference sequence.
Most cases of congenital adrenal hyperplasia (CAH) are caused by mutations in this gene, and most mutations appear to arise from gene conversion-like events involving the transfer of deleterious sequences from the pseudogene, CYP21P, which is located within 30 kb of CYP21.
Because many women with 21-hydroxylase (21-OH)-deficient nonclassic adrenal hyperplasia (NCAH) carry at least one allele affected by a severe mutation of CYP21, they are at risk for giving birth to infants with classic adrenal hyperplasia (CAH).
Many patients with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency have CAH-X syndrome, a connective tissue dysplasia consistent with hypermobility-type Ehlers-Danlos syndrome due to a contiguous gene deletion involving the adjacent CYP21A2 and TNXB genes.
It has been demonstrated that one reaction for PCR amplification of the CYP21 gene and the chimeric CYP21P/CYP21 gene using mixed primers in combination with nested PCR and single-strand conformation polymorphism is considered highly efficient and accurate for molecular diagnosis of CAH due to 21-hydroxylase deficiency.
In order to test the hypothesis that mutations in the 5' non-coding region of CYP21 gene could contribute to the various spectrum of disease presentation due to 21-OH deficiency, the 400bp nucleotide sequence upstream of the ATG codon of CYP21 gene has been characterized in 28 CAH patients who have previously been genotyped by screening for the ten most frequent CYP21 mutations.
Congenital adrenal hyperplasia (CAH) due to CYP21A2 gene mutations is associated with a variety of clinical phenotypes (salt wasting, SW; simple virilizing, SV; nonclassical, NC) depending on residual 21-hydroxylase activity.
A point mutation within exon 7 producing an amino acid coding change and a recognition site for the endonuclease Ncol has been reported in the HLA-Bw47-linked CYP21A pseudogene and some mutant CYP21B (steroid 21-hydroxylase) genes of patients with congenital adrenal hyperplasia (CAH).
The correlation of genotype to phenotype in congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency has been investigated thoroughly since the mapping of the CYP21 gene to the short arm of chromosome 6.
This study assessed the clinical and laboratory factors involved in BMD of 45 patients at the Pediatric Unit of Endocrinology, UNICAMP, who had been diagnosed as having classical CAH due to CYP21A2 deficiency including molecular characterization.
By sequence analysis of the CYP21A2 gene, we identified two novel (I171N and L446P) and two rare (R341P and R426H) mutations in seven Italian patients with CAH.
Here we report on a three-generation family with a heterozygous deletion encompassing CYP21A2 and TNXB that initially came to medical attention due to the diagnosis of CAH in the proposita.
The second CYP21A2 was free ofCAH-causing mutations and produced mRNA in the adrenal gland, confirming its functionality and ability to rescue the carriers from CAH.
We conclude that a single, unequal crossingover between the CYP21A and the CYP21B genes yields deletion of the active CYP21 gene and salt-losing CAH and that these crossingovers do not occur randomly within the CYP21 genes of our patients.
Detection of underlying mutations in CYP21A2 gene encoding steroid 21-hydroxylase enzyme is helpful both for confirmation of diagnosis and management of CAH patients.
The contiguous gene deletion syndrome (CAH-X) was described in a subset (7%) of congenital adrenal hyperplasia (CAH) patients with a TNXA/TNXB chimera, resulting in deletions of CYP21A2, encoding 21-hydroxylase necessary for cortisol biosynthesis, and TNXB, encoding the extracellular matrix glycoprotein tenascin-X (TNX).