CYP21A2 mutations in pediatric patients with congenital adrenal hyperplasia in Costa Rica

Characterization of the CYP21A2 Gene Mutations in Children with Classic Congenital Adrenal Hyperplasia

OBJECTIVE

To characterize the CYP21A2 gene mutations in children with classic congenital adrenal hyperplasia (CAH).

METHODS

A prospective, cross-sectional study was conducted on 24 children with classic CAH. Molecular characterization of the CYP21A2 gene was carried out by Sanger sequencing, multiplex ligation-dependent probe amplification (MLPA), or clinical exome sequencing. Another 21 previously mutation-proven CAH patients were also included and a combined result was drawn.

RESULTS

Out of 45 children, pathogenic variants in the CYP21A2 gene were identified in 43 patients (95.5%). Homozygous, probable compound heterozygous, and heterozygous variants were seen in 69%, 22%, and 18% of patients, respectively. The most common variant was c.293-13C/A>G (33%), followed by deletion/duplication (24%), and c.955C>T (p.Gln319Ter) (21%), similar to previous Indian studies. Allelic frequencies of c.332_339del and c.518 T>A (p.Ile173Asn) were 9% and 4%, respectively. Less common variants were c.923dupT (p.Leu308PhefsTer6), c.92C>T (p.Pro31Leu), c.1069C>T (p.Arg357Trp), c.1267G>C (p.Gly423Arg), and c.710_719delins (p.Ile237_Met240delinsAsnGluGluLys). A good genotype-phenotype correlation was observed; only p.Pro31Leu and p.Ile173Asn variants showed discordance. The diagnostic yield of Sanger sequencing alone, Sanger sequencing with MLPA, and clinical exome alone was 85%, 100%, and 100%, respectively.

CONCLUSIONS

All children, except two, diagnosed clinically as classic CAH, showed pathogenic variants in the CYP21A2 gene; the most common variant was c.293-13 C/A>G. The results suggest a broad mutation spectrum in the authors' single-center cohort of children with CAH. Clinical exome sequencing is the preferred stand-alone method for molecular diagnosis of CAH.

Characteristics of Congenital Adrenal Hyperplasia Diagnosed in Adulthood: A Literature Review and Case Series

Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders characterized by impaired cortisol synthesis. CAH, depending on its clinical form, is usually diagnosed in the neonatal period, later in childhood, in adolescence, or in young adults. Herein, we report a case series of eight individuals in whom CAH was diagnosed between the ages of 18 and 81 years.

METHODS

We report on clinical presentations, hormonal tests, adrenal/gonadal imaging, and genetic findings. The clinical data of eight people with CAH, including four women (46, XX) and four men (46, XY), were reviewed. A genetic analysis of the cytochrome P450 family 21 subfamily A member 2 (CYP21A2) gene was performed in six patients. A comprehensive literature review was also conducted.

CASE SERIES

Partial cortisol deficiency was found in all patients. The most frequent genotype was the homozygotic I173N mutation in CYP21A2. Adrenal masses were detected in seven patients, except for the youngest. Most of the patients were of short stature. Hypogonadotropic hypogonadism was detected in two males, and three females presented with primary amenorrhea. Hirsutism was noticeable in three females. All of the patients developed insulin resistance, and half of them were obese.

CONCLUSIONS

The clinical presentations of different forms of CAH overlapped. Genotype-phenotype correlations were strong but not absolute. The management of CAH should be individualized and based on clinical and laboratory findings. Furthermore, the assessment of the cortisol response to adrenocorticotrophic hormone stimulation should be mandatory in all adults with CAH. Additionally, the regular long-term screening of cardiometabolic status is required in the CAH population.

Copy Number Variations in Genetic Diagnosis of Congenital Adrenal Hyperplasia Children

Background: Congenital adrenal hyperplasia (CAH) is a monogenic disorder caused by genetic diversity in the CYP21A2 gene, with 21-hydroxylase deficiency (21-OHD) as the most common type. Early sex assignment and early diagnosis of different genetic variations with a proper technique are important to reduce mortality and morbidity. Proper early sex identification reduces emotional, social, and psychological stress.

Aim: Detection of a spectrum of aberrations in the CYP21A2 gene, including copy number variations, gene conversion, chimeric genes, and point variations.

Methods: The CYP21A2 gene was screened using MLPA assay in 112 unrelated Egyptian children with 21-OHD CAH (33 males and 79 females).

Results: In the studied group, 79.5% were diagnosed within the first month of life. 46.8% of the genetic females were misdiagnosed as males. Among the copy number variation results, large deletions in 15.4% and three types of chimeric genes in 9% (CH-1, CH-7, and CAH-X CH-1) were detected. Regarding gene dosage, one copy of CYP21A2 was found in 5 cases (4.5%), three copies were detected in 7 cases (6.3%), and one case (0.9%) showed four copies. Eight common genetic variants were identified, I2G, large deletions, large gene conversion (LGC), I172N, F306 + T, -113 SNP, 8bp Del, and exon 6 cluster (V237E and M239K) with an allelic frequency of 32.62%, 15.45%, 7.30%, 3.00%, 2.58%, 2.15%, 0.86%, and 0.86%, respectively.

Conclusion: High prevalence of copy number variations highlights the added value of using MLPA in routine laboratory diagnosis of CAH patients.