Detected heterozygotes during the molecular analysis of the common CYP21A2 point mutations in Macedonian patients with congenital adrenal hyperplasia and their relatives.

Background: Deficiency of 21-hydroxylase is present in 90-95% cases of congenital adrenal hyperplasia (CAH), an autosomal recessive disorder. Eleven common pseudogene-derived mutations account for approximately 95% of all affected CYP21A2 alleles in all three clinical forms of the disease.

Objective: To analyse the detected heterozygotes during the molecular analysis of eleven CYP21A2 common pseudogene-derived point mutations in Macedonian CAH patients and their relatives, using the PCR-ACRS protocol.

Methods: We performed direct molecular detection of CYP21A2 mutations: p.P30L, IVS2-655 C/A→G, G110Δ8nt, p.I172N, p.I236N, p.V237E, p.M239K, p.F306+t, p.V281L, p.Q318X and p.R356W, in 51 CAH Macedonian patients and their 70 healthy relatives (parents and siblings), using the differential PCR-ACRS protocol.

Results: Six of the analysed mutations were detected in 29.4% (15/51) of the patients, in the heterozygous state, with the following distribution: IVS2-655 C/A→G (13.7%), p.P30L (11.8%), p.Q318X (9.8%), p.I172N (3.9%), p.R356W (3.9%) and p.V281L (1.96%). Six cases (6/15) were compound heterozygotes and nine (9/15) were simple heterozygotes. Genotype-phenotype correlation was observed in all of our detected compound heterozygote patients. Their clinical presentation was correlated with the less severely mutated allele. Four of the analysed mutations (p.P30L 20%, IVS2-655 C/A→G 12.9%, p.Q318X 7.1% and p.R356W 2.9%) appeared in thirty healthy relatives (42.9%), in the heterozygous state.

Conclusions: Distribution of the analysed CYP21A2 mutations among CAH patients and their relatives is comparable to studies from other populations. As expected, high carrier frequency of alleles causing 21-hydroxylase deficiency was observed in relatives of CAH patients.