Structure-Based Analysis of Five Novel Disease-Causing Mutations in 21-Hydroxylase-Deficient Patients

Carolina Minutolo,Noemí Buzzalino,Eduardo H Charreau,Liliana Alba,Cecilia Fernández,Bárbara Casali,Liliana Dain,Melisa Taboas,Susana Belli,Alejandro D Nadra

doi:10.1371/journal.pone.0015899

Abstract

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is the most frequent inborn error of metabolism, and accounts for 90–95% of CAH cases. The affected enzyme, P450C21, is encoded by the CYP21A2 gene, located together with a 98% nucleotide sequence identity CYP21A1P pseudogene, on chromosome 6p21.3. Even though most patients carry CYP21A1P-derived mutations, an increasing number of novel and rare mutations in disease causing alleles were found in the last years. In the present work, we describe five CYP21A2 novel mutations, p.R132C, p.149C, p.M283V, p.E431K and a frameshift g.2511_2512delGG, in four non-classical and one salt wasting patients from Argentina. All novel point mutations are located in CYP21 protein residues that are conserved throughout mammalian species, and none of them were found in control individuals. The putative pathogenic mechanisms of the novel variants were analyzed in silico. A three-dimensional CYP21 structure was generated by homology modeling and the protein design algorithm FoldX was used to calculate changes in stability of CYP21A2 protein. Our analysis revealed changes in protein stability or in the surface charge of the mutant enzymes, which could be related to the clinical manifestation found in patients.

Highlights

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (OMIM 201910) accounts for 90–95% of CAH cases [1,2]
This combined strategy revealed the presence of five novel mutations in four nonclassical form of CAH (NCCAH) and one SW 21-hydroxylase-deficient patients from our cohort
In patient 2, g.940C.T mutation located in exon 4 replaces an arginine residue with a cysteine at position 149, and in patient 3, g.1695A.G mutation in exon 7 leads to a change in residue M283 to V283

Summary

Introduction

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (OMIM 201910) accounts for 90–95% of CAH cases [1,2]. This autosomal recessive disorder, which is the most frequent inborn error of metabolism, has a broad spectrum of clinical forms, ranging from severe or classical, which includes the salt-wasting (SW) and simple virilising (SV) forms, to the mild late onset or nonclassical form of CAH (NCCAH) [1]. With or without aldosterone deficiency, results in chronic stimulation of the adrenal cortex by corticotropin (ACTH). The moderate enzyme deficiency that results in NCCAH is characterized by signs of hyperandrogenism such as early pubarche, hirsutism, oligomenorrhea or amenorrhea, polycystic ovaries, acne, and/or infertility

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Conclusion