Heterozygous mutations in the cholesterol side-chain cleavage enzyme gene (CYP11A1) can cause transient adrenal insufficiency and life-threatening failure to thrive

Differential tissue expression of sex steroid-synthesizing enzyme CYP11A1 in male Tibetan sheep (Ovis aries)

Steroid metabolism is a fundament to testicular development and function. The cytochrome P450, family 11, subfamily A, polypeptide 1 (CYP11A1) is a key rate-limiting enzyme for catalyzing the conversion of cholesterol to pregnenolone. However, despite its importance, what expression and roles of CYP11A1 possesses and how it regulates the testicular development and spermatogenesis in Tibetan sheep remains largely unknown. Based on this, we evaluated the expression and localization patterns of CYP11A1 in testes and epididymides of Tibetan sheep at three developmental stages (three-month-old, pre-puberty; one-year-old, sexual maturity and three-year-old, adult) by quantitative real-time PCR (qPCR), western blot and immunofluorescence. The results showed that CYP11A1 mRNA and protein were expressed in testes and epididymides throughout the development stages and obviously more intense in one- and three-year-old groups than three-month-old group (except for the caput epididymidis). Immunofluorescence assay showed that the CYP11A1 protein was mainly located in Leydig cells and epididymal epithelial cells. In addition, positive signals of CYP11A1 protein were observed in germ cells, epididymal connective tissue and sperms stored in the epididymal lumen. Collectively, these results suggested that the CYP11A1 gene might be mainly involved in regulating spermatogenesis and androgen synthesis in developmental Tibetan sheep testis and epididymis.

Side-chain cleavage enzyme deficiency: Systematic review and case series

OBJECTIVE

P450 side-chain cleavage deficiency (SCCD) patients present with primary adrenal insufficiency (PAI) with or without undervirilized external genitalia. The distinction between classic and nonclassic steroidogenic acute regulatory protein deficiency has been described, whereas in SCCD is unclear. The data on gonadal function and its correlation with SCCD genotype has not been studied. We describe our experience and perform a systematic review of genetically proven SCCD patients to determine the distinct phenotypic and genotypic characteristics of 46,XY SCCD patients with typical male external genitalia (SCCD-TMG) and atypical (SCCD-AG) external genitalia.

DESIGN, PATIENTS AND MEASUREMENTS

Retrospective review of three genetically proven SCCD patients from our centre and per-patient data analysis from a systematic review of 52 probands was performed. SCCD-TMG (n = 19) was defined as external genitalia of Sinnecker score 1 with 46,XY  karyotype; the rest (Sinnecker 2-5) were classified as SCCD-AG (n = 15).

RESULTS

We report two new Indian cases of SCCD with three novel likely pathogenic variants and pubertal follow-up of a previously reported patient. In systematic review, age at diagnosis of PAI and elevated renin were not different between 46,XY  SCCD-TMG (n = 19) and SCCD-AG (n = 15), whereas spontaneous puberty (9/9 vs. 0/3, p = .0045), normal prepubertal (5/5 vs. 6/6, p = .002), pubertal gonadotropins (2/9 vs. 0/3, p = 1) and normal pubertal testosterone (9/11 vs. 0/3, p = .027) were more common in SCCD-TMG. Testicular adrenal rest tumours were exclusive to SCCD-TMG (n = 4). SCCD-TMG was associated with four particular genotypes [monoallelic p.Glu314Lys with another deleterious variant on the second allele (p.Glu314Lys/X-CHS: X-compound heterozygous state), biallelic p.Arg451Trp, p.Phe215Ser/p.Arg232Ter and monoallelic p.Val79Ile]. 46,XX SCCD  patients with p.Glu314Lys/X-CHS also had normal gonadotropins with spontaneous puberty.

CONCLUSION

SCCD-TMG is associated with four specific genotypes and distinct gonadal characteristics from SCCD-AG with overlapping features of PAI.

Computational analysis on two putative mitochondrial protein-coding genes from the Emydura subglobosa genome: A functional annotation approach

Rapid advancements in automated genomic technologies have uncovered many unique findings about the turtle genome and its associated features including olfactory gene expansions and duplications of toll-like receptors. However, despite the advent of large-scale sequencing, assembly, and annotation, about 40-50% of genes in eukaryotic genomes are left without functional annotation, severely limiting our knowledge of the biological information of genes. Additionally, these automated processes are prone to errors since draft genomes consist of several disconnected scaffolds whose order is unknown; erroneous draft assemblies may also be contaminated with foreign sequences and propagate to cause errors in annotation. Many of these automated annotations are thus incomplete and inaccurate, highlighting the need for functional annotation to link gene sequences to biological identity. In this study, we have functionally annotated two genes of the red-bellied short-neck turtle (Emydura subglobosa), a member of the relatively understudied pleurodire lineage of turtles. We improved upon initial ab initio gene predictions through homology-based evidence and generated refined consensus gene models. Through functional, localization, and structural analyses of the predicted proteins, we discovered conserved putative genes encoding mitochondrial proteins that play a role in C21-steroid hormone biosynthetic processes and fatty acid catabolism-both of which are distantly related by the tricarboxylic acid (TCA) cycle and share similar metabolic pathways. Overall, these findings further our knowledge about the genetic features underlying turtle physiology, morphology, and longevity, which have important implications for the treatment of human diseases and evolutionary studies.

Cyp11a2 Is Essential for Oocyte Development and Spermatogonial Stem Cell Differentiation in Zebrafish

Cytochrome P45011A1, encoded by Cyp11a1, converts cholesterol to pregnenolone (P5), the first and rate-limiting step in steroidogenesis. In zebrafish, cyp11a1 is maternally expressed and cyp11a2 is considered the ortholog of Cyp11a1 in mammals. A recent study has shown that depletion of cyp11a2 resulted in steroidogenic deficiencies and the mutants developed into males with feminized secondary sexual characteristics. Here, we independently generated cyp11a2 mutants in zebrafish and showed that the mutants can develop into males and females in the juvenile stage, but finally into infertile males with defective mating behavior in the adult stage. In the developing ovaries, the cyp11a2 mutation led to stage I oocyte apoptosis and final sex reversal, which could be partially rescued by treatment with P5 but not estradiol. In the developing testes, depletion of cyp11a2 resulted in dysfunction of Sertoli cells and lack of functional Leydig cells. Spermatogonial stem cells (SSCs) in the mutant testes underwent active self-renewal but no differentiation, resulting in a high abundance of SSCs in the testis, as revealed by immunofluorescence staining with Nanos2 antibody. The high abundance and differentiation competence of SSCs in the mutant testes were verified by a novel testicular cell transplantation method developed in this study, by transplanting mutant testicular cells into germline-depleted wild-type (WT) fish. The transplanted mutant SSCs efficiently differentiated into functional spermatids in WT hosts. Overall, our study demonstrates the functional importance of cyp11a2 in early oogenesis and differentiation of SSCs.

A Novel Homozygous Mutation in CYP11A1 Gene is Associated with Severe Adrenal Insufficiency in 46, XX Patient

One of the causes of congenital adrenal insufficiency, a genetically heterogeneous disorder is a mutation in the CYP11A1 gene, which is responsible for the initiation of steriodogenesis by converting cholesterol to pregnenolone. Case: In a now 3 years and 3 months-old girl, adrenal insufficiency was diagnosed in the neonatal period. Clinical exome sequencing for primary adrenal insufficiency revealed a homozygous p.Thr330Met (c.989C>T) variant in the CYP11A1 (NM_000781) gene. Conclusion: Different types of inheritance patterns have been observed in CYP11A1-related adrenal insufficiency cases. We consider our case is an due to an autosomal recessive inheritance.

Congenital Adrenal Hyperplasias Presenting in the Newborn and Young Infant

Congenital adrenal hyperplasia includes autosomal recessive conditions that affect the adrenal cortex steroidogenic enzymes (cholesterol side-chain cleavage enzyme; 3β-hydroxysteroid dehydrogenase; 17α-hydroxylase/17,20 lyase; P450 oxidoreductase; 21-hydroxylase; and 11β-hydroxylase) and proteins (steroidogenic acute regulatory protein). These are located within the three major pathways of the steroidogenic apparatus involved in the production of mineralocorticoids, glucocorticoids, and androgens. Many countries have introduced newborn screening program (NSP) based on 17-OH-progesterone (17-OHP) immunoassays on dried blood spots, which enable faster diagnosis and treatment of the most severe forms of 21-hydroxylase deficiency (21-OHD). However, in several others, the use of this diagnostic tool has not yet been implemented and clinical diagnosis remains challenging, especially for males. Furthermore, less severe classic forms of 21-OHD and other rarer types of CAHs are not identified by NSP. The aim of this mini review is to highlight both the main clinical characteristics and therapeutic options of these conditions, which may be useful for a differential diagnosis in the neonatal period, while contributing to the biochemical evolution taking place in the steroidogenic field. Currently, chromatographic techniques coupled with tandem mass spectrometry are gaining attention due to an increase in the reliability of the test results of NPS for detecting 21-OHD. Furthermore, the possibility of identifying CAH patients that are not affected by 21-OHD but presenting elevated levels of 17-OHP by NSP and the opportunity to include the recently investigated 11-oxygenated androgens in the steroid profiles are promising tools for a more precise diagnosis and monitoring of some of these conditions.