HLA-A, B, C, DR alleles in congenital adrenal hyperplasia

Congenital Adrenal Hyperplasia and Human Leukocyte Antigen B: A Meta-Analysis

The link between specific human leukocyte antigen (HLA)-B genes and congenital adrenal hyperplasia (CAH) has been a subject of interest. This study investigates the association between specific HLA-B haplotypes and CAH through a meta-analysis. Google Scholar was used as a database. Articles were included if the research was conducted between 1970 and 2022, was not a meta-analysis, and had odds ratios or enough data points to calculate an odds ratio. The National Institutes of Health (NIH) quality assessment tool of case-control studies was used to evaluate the risk of bias in individual studies, and MetaXL was used to generate data and create a forest plot for analysis. Twelve studies met the selection criteria and were included in the study (641 patients and 3,614 controls). Two HLA-B haplotypes showed increased odds of CAH compared to controls: B14 (OR=3.81; 95%CI=2.88, 5.05; I2=3%) and B35 (OR=1.88; 95%CI=1.22, 2.90; I2=25%). All other HLAs either showed no significant effect or had high heterogeneity. The results suggest that specific HLA-B haplotypes have increased odds of developing CAH, specifically B14 and B35. These findings may prove helpful in the pre- and post-natal diagnosis of CAH as well as the identification of carriers and prediction of patient prognosis.

Diagnosis of homozygosity and heterozygosity in congenital adrenal hyperplasia (CAH) and control of treatment

In congenital adrenal hyperplasia the incidence of 21-hydroxylase deficiency is very high (approximately 1:7,000), whereas other enzyme defects such as 11-hydroxylase deficiency, 17-hydroxylase deficiency and 3 beta-hydroxysteroid dehydrogenase deficiency are much less frequent. The various forms of enzyme defects can be diagnosed by determining specific plasma steroids or specific urinary steroid metabolites. A new semi-automatic capillary gas liquid chromatography method has been introduced for the diagnosis of CAH and assessment of therapy. Heterozygous carriers of 21-hydroxylase deficiency can be detected in the general population by measuring 17-hydroxyprogesterone plasma levels after ACTH stimulation; however, results overlap with the general population. In families with a CAH index case, heterozygosity and homozygosity for the 21-hydroxylase deficiency gene can be detected by HLA-typing. 21-hydroxylase deficiency can be diagnosed prenatally by HLA-typing or by determining 17 OH-progesterone levels in the amniotic fluid.

Extended MHC haplotypes in 21-hydroxylase-deficiency congenital adrenal hyperplasia: shared genotypes in unrelated patients

HLA, complement, and glyoxalase I alleles were studied in 29 families in which at least one member has classical 21-hydroxylase-deficiency congenital adrenal hyperplasia. A rare complement allele, C4B*31, was found in over 20% of the haplotypes defined in these families and was always part of the complement haplotype BF*F, C2*C, C4A*Q0, C4B*31 (abbreviated FCO,31). The haplotype containing this rare set of complement alleles always carried the rare HLA allele, HLA-Bw47, usually carried HLA-A3, and almost always had the alleles HLA-Cw6, HLA-DR7, and the glyoxalase I (GLO) allele GLO1. Thus over 20% of the haplotypes in the population studied contained all or almost all of the rare extended haplotype HLA-(A3), Bw47, Cw6,DR7, FCO,31, GLO 1. 3 other haplotypes were each found twice in unrelated patients concordant for their disease phenotype and ethnic background. Extended MHC haplotypes may be markers for different genetic mutations causing 21-hydroxylase deficiency.

HLA genotypes and HLA-linked genetic markers in Italian patients with classical 21-hydroxylase deficiency

HLA genotype and HLA-linked marker data for 40 unrelated patients from central Italy and 2 unrelated patients from Sardinia with congenital adrenal hyperplasia due to 21-hydroxylase deficiency (21-OH-def) were analyzed. The results confirm that the HLA-linked 21-OH-def gene is associated with several different HLA determinants and complete HLA haplotypes, although the only determinant with significantly increased frequency was the complement C2 allele C2B. The HLA antigens B8 and DR3 were found in significantly decreased frequencies. The haplotype A3, Cw6, Bw47, BfF, DR7, which is exceptionally rare in the general population but which has been found in many other 21-OH-def patients from diverse geographical origins, was also found in one of the Italian patients. This and other HLA haplotype associations found among the Italian patients may represent mutations that have occurred on HLA haplotypes with genetic linkage disequilibrium or, alternatively, may represent mutations that have not yet had time to become randomly associated with different HLA complex determinants. The marked negative associations with B8 and DR3 could, however, result from an interaction between the gene products of the HLA complex and the 21-OH-def phenotype.

Prenatal diagnosis of congenital adrenal hyperplasia (21-OH deficiency type) by HLA typing

The close genetic linkage between HLA-B and congential adrenal hyperplasia due to 21-hydroxylase deficiency permits prenatal diagnosis of an affected fetus by HLA typing of amniotic fluid cells in pregnancies at risk. Some families at risk, especially those with an affected girl with ambiguous genitalia, will only plan another pregnancy if a prenatal diagnosis is possible. After HLA typing of the index case, parents and eventually grandparents, the family were informed of the possibility of a prenatal diagnosis. Fibroblast cell lines were initiated from skin biopsies of the index cases and parents and were used as controls in the tests. HLA typing of the fetus was done on amniotic fluid cells grown in vitro using first, a microcytotoxicity test and second quantitative microabsorption test. Ten prenatal diagnoses are reported. In two cases the HLA genotype indicated an affected fetus, examination of the aborted fetuses was in agreement with the diagnosis. In one case an affected male fetus was diagnosed, the pregnancy is in progress. In seven cases an unaffected infant was predicted (four carriers and three homozygous normal infants).