Fernández CS, Taboas M, Bruque CD, et al. - Given that 21‐hydroxylase deficiency is the most common cause of congenital adrenal hyperplasia, researchers sought to examine the CYP21A2 gene defects in a large cohort of Argentine individuals. They analyzed molecular characterization of 628 patients (168 classical, 460 nonclassical (NC), representing 1203 non‐related alleles), 398 relatives, 126 partners. Genetic variants have been evaluated by allele‐specific PCR, PCR‐RFLP or direct sequencing. Data reported that p.V282L (58%) in NC alleles and c.293‐13 A/C>G (31.8%) and p.I173N (21.1%) in classical were the most frequent pathogenic variants. Genotype‐phenotype correlation was noted in 98.6% of the cases, 11 asymptomatic first‐degree relatives had pathogenic variants in both alleles and 21/126 partners were carriers. They performed a comprehensive genetic characterization of the largest cohort of 21‐hydroxylase patients from the region. In particular, they add to the molecular characterization of a large number of NC individuals and to the estimation of the frequency of the disease carrier in the population.