Complete androgen insensitivity syndrome caused by c.1769-1G > C mutation and activation of a cryptic splice acceptor site in the androgen receptor gene

A spectrum of epididymis and vas deferens anomalies among children with cryptorchidism: a retrospective multi-center study

Background

Vasoepididymal anomalies are not rare among children with cryptorchidism. They may affect fertility following orchiopexy. Herein, we describe the cases of abnormalities of the vas deferens and epididymis in children undergoing orchidopexy for cryptorchidism. Data were collected retrospectively from six centers providing care for patients with undescended testicles from September 2017 to February 2019. All patients whose congenital anomalies of the epididymis or vas deferens were discovered incidentally during operative intervention for cryptorchidism and where photographs of the anomalies were taken were included.

Results

The total incidence of congenital anomalies on the 467 testicles which had operations was 13.2%. Congenital epididymal and vas deferens anomalies were more common on the left side than the right side in patients with cryptorchidism (P = 0.038). Attachment anomalies between the epididymis and testis were the most common epididymal anomaly (36.3%), while a vanished vas deferens was the most frequent vas deferens anomaly (18%). Three patients had absent vas deferens, two had curled vas deferens, two had vas deferens separated from the epididymis, and one had a duplicated vas deferens. Three patients had an epididymal cyst, one had an enlarged appendix of the epididymis, and one had epididymal agenesis.

Conclusion

Attention must be paid during any surgery on an undescended testicle as an anomaly of the vas deferens could lead to unexpected complications. Anomalies of the vas deferens or epididymis that present in cases of cryptorchidism occur mostly on the left side.

A novel cryptic splice site mutation in COL1A2 as a cause of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is an inherited genetic disorder characterized by frequent bone fractures and reduced bone mass. Most cases of OI are caused by dominantly inherited heterozygous mutations in one of the two genes encoding type I collagen, COL1A1 and COL1A2. Here we describe a five-year-old boy with typical clinical, radiological and bone ultrastructural features of OI type I. Establishing the molecular genetic cause of his condition proved difficult since clinical exome and whole exome analysis was repeatedly reported negative. Finally, manual analysis of exome data revealed a silent COL1A2 variant c.3597 T > A (NM_000089.4), which we demonstrate activates a cryptic splice site. The newly generated splice acceptor in exon 50 is much more accessible than the wild-type splice-site between the junction of exon 49 and 50, and results in an in-frame deletion of 24 amino acids of the C-terminal propeptide. In vitro collagen expression studies confirmed cellular accumulation and decreased COL1A2 secretion to 45%. This is the first report of a cryptic splice site within the coding region of COL1A2. which results in abnormal splicing causing OI. The experience from this case demonstrates that routine diagnostic approaches may miss cryptic splicing mutations in causative genes due to the lack of universally applicable algorithms for splice-site prediction. In exome-negative cases, in-depth analysis of common causative genes should be conducted and trio-exome analysis is recommended.

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Our study highlights a new category of mutations found in COL1A2.

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Manual screening of WES data identified the cryptic splice site in COL1A2

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NGS may miss cryptic splicing mutations in causative genes

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Universally applicable algorithms for splice-site prediction are needed

Analysis of testosterone pathway genes in dogs (78,XY; SRY-positive) with ambiguous external genitalia revealed a homozygous animal for 2-bp deletion causing premature stop codon in HSD17B3

The genetic background of disorders of sex development (DSD) in dogs with a normal male sex chromosome set (78,XY) is poorly described. In this study, we present for the first time, an analysis of six genes of the testosterone pathway, encoding enzymes (CYP17A1, HSD3B2, HSD17B3, SRD5A2) and transcription factors (NR5A1, AR). The entire coding sequence and flanking regions of the introns, 5'-UTR and 3'-UTR were analyzed in five DSD dogs (78,XY, SRY-positive) with ambiguous external genitalia and in 15 control dogs. A homozygous deletion of 2 bp in exon 2 of HSD17B3 (hydroxysteroid 17-beta dehydrogenase 3) was found in a Dachshund dog with enlarged clitoris, vulva and abdominal gonads and decreased serum testosterone level. In silico analysis revealed that this deleterious variant causes truncation of the encoded polypeptide (from 306 to 65 amino acids) and deprivation of the active site of the encoded enzyme. Genotyping of 23 control Dachshund dogs showed a normal homozygous genotype. Thus, we assumed that the 2-bp deletion is the causative variant. Moreover, 24 SNPs (four in CYP17A1, three in HSD3B2, six in HSD17B3, five in SRD5A2, one in AR and five in NR5A1), two intronic indels (one in HSD3B2 and one in SRD5A2) and two microsatellite polymorphisms in exon 1 of AR were found. Six SNPs appeared to be novel. No association with DSD phenotype was observed. Identification of the first case of DSD in domestic animals caused by a deleterious variant of a gene involved in testosterone synthesis showed that these genes are important candidates in such studies.

New mutation causing androgen insensitivity syndrome - a case report and review of literature

Androgen insensitivity syndrome (AIS) is a congenital disorder in which a defect in the androgen receptor (AR) gene leads to cellular resistance to androgens. Defects in the AR gene, located on the X chromosome, result in the development of a feminine phenotype in chromosomally male (46, XY) individuals. In this case report, we present a 44 years old patient with complete androgen insensitivity syndrome (CAIS) initially presenting with primary amenorrhea. The patient underwent a full clinical evaluation, revealing hypoplastic vagina and a lack of uterus and ovaries. Hormonal evaluation revealed markedly elevated testosterone, FSH, and LH serum concentrations. Diagnostic imaging, including pelvic MRI, confirmed the presence of two solid masses in the inguinal canals (right 26 × 13 mm, left 25 × 15 mm). The patient underwent genetic testing, revealing a 46 XY karyotype and an as of yet unprecedented androgen receptor mutation. The type of the mutation was a single-base exchange - the substitution from cytosine to thymine in chromosome X:66942710 position (referred to human reference genome GRCh37), which has resulted in an amino acid changes from leucine (CTT) to phenyloalanine (TTT) in ligand-binding domain.