Genotype-phenotype correlation in 27 pediatric patients in congenital adrenal hyperplasia due to 21-hydroxylase deficiency in a single center

Challenges of CYP21A2 genotyping in children with 21-hydroxylase deficiency: determination of genotype-phenotype correlation using next generation sequencing in Southeastern Anatolia

BACKGROUND/PURPOSE

Although it is known that there is generally a good correlation between genotypes and phenotypes, the number of studies reporting discrepancies has recently increased, exclusively between milder genotypes and their phenotypes due to the complex nature of the CYP21A2 gene and methodological pitfalls. This study aimed to assess CYP21A2 genotyping in children with 21-hydroxylase deficiency (21-OHD) and establish their predictive genotype-phenotype correlation features using a large cohort in Southeastern Anatolia's ethnically diverse population.

METHODS

The patients were classified into three groups: salt-wasting (SW), simple virilizing (SV) and non-classical (NC). The genotypes were categorized into six groups due to residual enzyme activity: null-A-B-C-D-E. CYP21A2 genotyping was performed by sequence-specific primer and sequenced with next generation sequencing (NGS), and the expected phenotypes were compared to the observed phenotypes.

RESULTS

A total of 118 unrelated children with 21-OHD were included in this study (61% SW, 24.5% SV and 14.5% NC). The pathogenic variants were found in 79.5% of 171 mutated alleles (60.2%, 22.2%, and 17.6% in SW, SV and NC, respectively). Patient distribution based on genotype groups was as follows: null-16.1%, A-41.4%, B-6.0%, C-14.4%, E-22%). In2G was the most common pathogenic variant (33.9% of all alleles) and the most common variant in the three phenotype groups (SW-38.8%, SV-22.2% and NC-23.3%). The total genotype-phenotype correlation was 81.5%. The correlations of the null and A groups were 100% and 76.1%, respectively, while it was lower in group B and poor in group C (71.4% and 23.5%, respectively).

CONCLUSION

This study revealed that the concordance rates of the severe genotypes with their phenotypes were good, while those of the milder genotypes were poor. The discrepancies could have resulted from the complex characteristics of 21-OHD genotyping and the limitations of using NGS alone without integrating with other comprehensive methods.

Outcome of Newborn Screening for Congenital Adrenal Hyperplasia at Two Time Points

BACKGROUND/AIMS

Screening newborns for congenital adrenal hyperplasia (CAH) is problematic owing to the dynamic changes in serum 17-hydroxyprogesterone (17-OHP) levels following birth. Our study objectives were to determine the accuracy of screening, severity of CAH, and biochemical and clinical outcomes of cases detected by our program which collects specimens at 2 time periods following birth.

METHODS

We reviewed all CAH cases detected in the Northwest Regional Newborn Screening Program from 2003 through 2017. Comparison was made of screening and confirmatory serum 17-OHP, neonatal, maternal, and follow-up auxologic data, steroid treatment doses, and 21-hydroxylase genotype in cases detected on the first versus second test.

RESULTS

Out of 164 cases of CAH, 25% were detected on the second screen. Infants detected on the second test had a lower screening 17-OHP (147 vs. 294 ng/mL), lower confirmatory serum 17-OHP (7,772 vs. 14,622 ng/dL), and were more likely to have simple virilizing CAH. There were no identifiable neonatal or maternal factors associated with detection on the second test. 21-Hydroxylase genotypes overlapped in first versus second screen cases.

CONCLUSION

Early collection of specimens necessitated by early discharge resulted in milder CAH cases falling below the screening 17-OHP cutoff. In our program 25% of cases were detected on a routine second screen.

Genotype and clinical outcomes in children with congenital adrenal hyperplasia

BACKGROUND

The study aimed to delineate the genotypic features and endocrine / metabolic profiles in patients with 21-hydroxylase deficiency.

METHODS

Subjects were diagnosed with 21-hydroxylase deficiency by direct Sanger sequencing or multiple ligation-dependent probe amplification analysis and followed up in Pusan National University Children's Hospital from July 2008 to April 2019. The genotype, phenotype, and endocrine and metabolic profiles in children and young adults with congenital adrenal hyperplasia were investigated.

RESULTS

Of a total of 33 patients, 16 (48.5%) were males. Median age was 7.4 years (range, 0.1-23.8 years). Thirty (90.9%) had salt-wasting phenotypes. Eleven (33.3%) initially presented with abnormality in a neonatal screening test without other symptoms. Among the 17 girls, seven received genital surgery. Sixty-five alleles from the 33 patients were evaluated. The distribution of CYP21A2 gene mutations revealed an intron 2 splice site (c.293-13A>G or c.293-13C>G) mutation as the most common one (22, 33.8%), followed by c.518T>A (10, 15.4%) and a large deletion / conversion (7, 10.8%), in order. One novel mutation was detected, c.332del(p.G111fs). Among the 27 patients aged >2 years, fifteen (55.6%) were obese / overweight, and ten (37.0%) needed growth hormone therapy due to short stature. Among the seven subjects aged >2 years and having high-risk genotype, five had impaired fasting glucose, three had precocious puberty, and four used growth hormone. A greater proportion of the high current corticosteroid dose group had impaired fasting glucose than in the low-dose group (64.3 vs 23.1%, P = 0.031).

CONCLUSIONS

Early monitoring of endocrine and metabolic complications from childhood might benefit patients with congenital adrenal hyperplasia.

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

Steroid 21-hydroxylase deficiency accounts for 95% of congenital adrenal hyperplasia (CAH) cases. Newborn screening has allowed for early detection of the disease, and currently, molecular analysis can identify the genotypes of these patients. Phenotype-genotype correlation has been well described in previous studies. In Costa Rica, there is no data about the genetic background of these patients, nor their phenotypic correlation.

Design

Observational, retrospective, descriptive study based on the review of patient records who had a diagnosis of CAH and were performed molecular analysis using gene sequencing or MLPA during the period from 2006 to 2018 (N = 58).

Objective

To describe the clinical and genetic characteristics of CAH patients due to 21-hydroxylase deficiency at the National Children's Hospital “Dr. Carlos Sáenz Herrera”, Caja Costarricense de Seguro Social (CCSS) in Costa Rica.

Results

53% (31/58) of the patients were male and 80% (37/46) were born full term; 72% (42/58) had salt wasting phenotype, 9% (5/58) simple virilizing phenotype and 19% (11/58) non-classic phenotype. The most frequent variants were c.292+5G>A in 26% (15/58) of patients and Del/Del in 21% (12/58) of them.

Conclusions

The most frequent mutation in our study population was the c.292+5G>A, which was found in 15/58 patients. This rare variant has only been reported in three other studies so far but as an infrequent mutation in CAH patients. The genetic characteristics of Costa Rican patients differ from what has been documented worldwide and could respond to a founder effect.

The distribution of intrafamilial CYP21A2 mutant alleles and investigation of clinical features in Turkish children and their siblings in Southeastern Anatolia

Background The genotype-phenotype relationship shows regional variability in 21-hydroxylase deficiency (21-OHD) caused by mutations in the CYP21A2 gene. This study focuses on the genotype-phenotype compatibility between patients and their siblings in a region where consanguineous marriage is common. Methods The most common mutations (I2G-P30L-I172N-V237E-M239K-V281L-Q318X-R356W-F306 + nt) were studied in 60 children with 21-OHD and 40 siblings (12 symptomatic and 28 asymptomatic; mean age 5.89 ± 4.63 and 8.34 ± 2.22 years, respectively). The allele number (patients; 93 siblings; 70 alleles) was counted for each case. Salt wasting (SW; n = 38), simple virilizing (SV; n = 11) and non-classical congenital adrenal hyperplasia (NCCAH; n = 11) types were compared with their genotypes classified into groups Null-AB-C-D-E based on enzyme impairment. Results Disease-causing mutations were identified in unrelated alleles: 80 out of 93 alleles (86%) in the patients: SW, 51/56 (91%); SV, 14/16 (87.4%) and NCCAH, 15/21 (71.4%). There were 43 out of 70 alleles (61.4%) in the siblings (asymptomatic, 25/50 [50%]; symptomatic, 18/20 [90%]). The most frequently detected mutations in the patients were: I2G (22%), Q318X-P30L-V281L (13% each). The distribution of the most common mutations by clinical types was: SW: I2G-Q318X (30.2%-19.6%), SV: I172NI2G (37.5%-18.7%), NCCAH: V281L-P30L (33.3%-28.5%). In patients and symptomatic siblings, the concordance percentages by genotype groups were: Null (100%-100%), A (85%-60%), B (100%-Not applicable), C (41.6%-50%). Eleven out of 28 asymptomatic siblings had disease-causing mutations (four, severe; one, moderate; six, mild). The distribution of genotypes by phenotypes were: SW: Null-A (88%), SV: B-A (50%-41.6%), NCCAH: C (100%). Conclusions This study showed that the most common alleles were IN2G-Q381X-R356W-P30L-V281L in the children with 21-OHD and asymptomatic siblings, and that the phenotype can be predicted from the genotype except for the P30L-V281L. This result suggests that the most common mutations in 21-OHD are similar to previous reports, but that the genotype-phenotype compatibility is good except for group C showing regional variability, and that genotyping of siblings discovered new patients.

Translating genomics to the clinical diagnosis of disorders/differences of sex development

The medical and psychosocial challenges faced by patients living with Disorders/Differences of Sex Development (DSD) and their families can be alleviated by a rapid and accurate diagnostic process. Clinical diagnosis of DSD is limited by a lack of standardization of anatomical and endocrine phenotyping and genetic testing, as well as poor genotype/phenotype correlation. Historically, DSD genes have been identified through positional cloning of disease-associated variants segregating in families and validation of candidates in animal and in vitro modeling of variant pathogenicity. Owing to the complexity of conditions grouped under DSD, genome-wide scanning methods are better suited for identifying disease causing gene variant(s) and providing a clinical diagnosis. Here, we review a number of established genomic tools (karyotyping, chromosomal microarrays and exome sequencing) used in clinic for DSD diagnosis, as well as emerging genomic technologies such as whole-genome (short-read) sequencing, long-read sequencing, and optical mapping used for novel DSD gene discovery. These, together with gene expression and epigenetic studies can potentiate the clinical diagnosis of DSD diagnostic rates and enhance the outcomes for patients and families.

Congenital Adrenal Hyperplasia with Non-functional Mutations in Both Alleles in a Clinically Unaffected Infant

BACKGROUND

Results in neonatal screening programs aiming at detection of congenital adrenal hyperplasia (CAH) can only report elevated levels of 17-hydroxy-progesterone (17-OHP), without being able to differentiate presence or absence of salt loss.

AIM

To predict presence or absence of salt loss in newborn infants with CAH.

METHODS

The first specimen of suspected CAH in samples sent from People's Democratic Republic of Laos (Lao PDR) was investigated for known mutations in CAH associated with salt loss.

RESULTS

Molecular genetic diagnosis revealed mutations associated with loss of function in both alleles; however, the infant was clinically unaffected even without any corticosteroid substitution therapy.

CONCLUSIONS

Although molecular genetic methods can theoretically predict loss of function in CAH, our infant was clinically unaffected even without therapy at 6 years of age. We speculate that in CAH, remaining enzyme activity can be sufficiently high, despite the presence of loss of function mutations, which do not affect infants clinically.

High-Dose Hook Effect in 17-Hydroxyprogesterone Assay in a Patient with 21-Hydroxylase Deficiency

Congenital adrenal hyperplasia (CAH) describes a group of disorders characterized by enzyme defects in adrenal steroidogenesis. 21-hydroxylase deficiency (21-OHD) is the most commonly encountered form. The analysis of steroids in pediatric cases requires high-sensitivity assays. A 14-year-old Syrian girl was referred for evaluation of short stature, amenorrhea, and hirsutism. On physical examination, breast development was Tanner stage 1. She had a phallic clitoris with a single urogenital orifice. Laboratory findings revealed primary adrenal deficiency with high androgen levels and low levels of 17-hydroxyprogesterone (17-OHP), (<0.05 ng/mL) and estrogen. This unexpected result led to suspicion of a high-dose hook effect. The measurement was repeated after 1/10 dilution of serum, and a high level of 17-OHP (115.4 ng/mL) was detected with the same test-enzyme-linked immunosorbent assay (ELISA). Simple virilizing form of CAH (21-OHD) was suspected and confirmed with genetic analysis. After initiation of glucocorticoid therapy, breast development was noted along with a decrease in testosterone level and an increase in estrogen level. To our knowledge, this is the first case report of hook effect for 17-OHP immunoassay in a patient with 21-OHD. High-dose hook effect should be suspected in patients with CAH when the test results are incompatible with one another. Additionally, this case demonstrates that a high testosterone level can block aromatase activity and consequently also estrogen production and breast development.

CYP21A2 mutation analysis in Korean patients with congenital adrenal hyperplasia using complementary methods: sequencing after long-range PCR and restriction fragment length polymorphism analysis with multiple ligation-dependent probe amplification assay

CYP21A2 mutation analysis of congenital adrenal hyperplasia (CAH) is challenging because of the genomic presence of a homologous CYP21A2 pseudogene and the significant incidence of pseudogene conversion and large deletions. The objective of this study was to accurately analyze the CYP21A2 genotype in Korean CAH patients using a combination of complementary methods. Long-range PCR and restriction fragment length polymorphism analyses were performed to confirm valid amplification of CYP21A2 and to detect large gene conversions and deletions before direct sequencing. Multiple ligation-dependent probe amplification (MLPA) analysis was conducted concurrently in 14 CAH-suspected patients and six family members of three patients. We identified 27 CYP21A2 mutant alleles in 14 CAH-suspected patients. The c.293-13A>G (or c.293-13C>G) was the most common mutation, and p.Ile173Asn was the second, identified in 25% and 17.9% of alleles, respectively. A novel frame-shift mutation of c.492delA (p.Glu 164Aspfs*24) was detected. Large deletions were detected by MLPA in 10.7% of the alleles. Mutation studies of the six familial members for three of the patients aided in the identification of haplotypes. In summary, we successfully identified CYP21A2 mutations using both long-range PCR and sequencing and dosage analyses. Our data correspond relatively well with the previously reported mutation spectrum analysis.