MYRF mutation leads to a single manifestation of sexual development and mimics partial androgen insensitivity syndrome: a case report and literature review

OBJECTIVE

To highlight the challenges in diagnosing 46, XY disorder of sex development related to MYRF mutation.

METHODS

We present an unusual case of a 12-year-old female child came for enlargement of clitoris and initially diagnosed as partial androgen insensitivity syndrome (AIS).

RESULTS

On examination, the patient's vulva was found virilized with 3cm-long clitoris. Her peripheral blood karyotype was 46, XY. The ultrasound showed an empty pelvis and hormone results confirmed hyperandrogenism. Therefore, the partial AIS was suspected, but the following whole exon sequencing indicates a pathological missense mutation in MYRF. Further investigation and surgery did not reveal any brain, heart, lung or diaphragm lesions related to MYRF, but only maldeveloped internal genitalia and a persistent urachus. Her serum testosterone dropped to normal after surgical removal of the remaining ipsilateral testis and epididymitis without spermatogenesis as shown by pathology.

CONCLUSION

Due to the karyotype, hyperandrogenism, empty pelvis but a virilism after puberty, the patient was initially diagnosed as partial AIS. This misleading clinical diagnose will not be verified as the MYRF mutation if without the whole exon sequencing, particularly in the absence of obvious brain, heart, lung and diaphragm lesions as in this case.

A Novel Intronic Splice-Site Mutation of the CYP11A1 Gene Linked to Adrenal Insufficiency with 46,XY Disorder of Sex Development

A novel CYP11A1: c.1236 + 5G > A was identified, expanding the mutation spectrum of the congenital adrenal insufficiency with 46,XY sex reversal. In a now 17-year-old girl delivered full-term (G2P2, parents unrelated), adrenal failure was diagnosed in the first year of life based on clinical picture of acute adrenal crisis with vomiting, dehydration, weight loss, hypotension, and electrolyte disturbances. At the time, hormonal tests revealed primary adrenocortical insufficiency and steroid profiles showed lack of products of steroidogenesis, and since then the patient has been treated with substitution doses of hydrocortisone and fludrocortisone. At the age of 14, considering the absence of puberty symptoms, extended diagnostic tests revealed elevated LH levels (26.5 mIU/mL) with pre-puberty FSH levels (4.9 mIU/mL), low estradiol (28 pmol/L), testosterone (<2.5 ng/mL), and extremely high levels of ACTH (4961 pg/mL). A cytogenetic study revealed a 46 XY karyotype. A molecular examination confirmed the missense mutation and a novel splice-site mutation of CYP11A1 gene. Compound heterozygosity for the CYP11A1 gene with a known pathogenic variant in one allele and a novel splice site mutation in the second allele is most probably responsible for congenital adrenal insufficiency with 46,XY sex reversal. We discuss the necessity of cytogenetic test in the case of early onset of adrenal failure in the absence of steroidogenesis metabolites in the steroid profile.

Analysis of XX SRY-Negative Sex Reversal Dogs

Simple Summary

The study of XX SRY-negative sex reversal cases is of great interest because testicular tissue develops in these subjects in the absence of SRY gene, thus allowing us to deepen the knowledge of all the other genes involved in the development of testes and the structures related to the male reproductive apparatus. This paper reports the results of the study of four new canine disorders of sex development (DSDs) XX SRY-negative cases in which 11 copy number variations (CNVs) are observed, five of which are never described.

Abstract

Impaired fertility associated with disorders of sex development (DSDs) due to genetic causes in dogs are more and more frequently reported. Affected dogs are usually of specific breeds thus representing a cause of economic losses for breeders. The aim of this research is to report the clinical, cytogenetic and molecular genetic findings of four XX SRY-negative DSD dog cases. All the subjects showed a female aspect and the presence of an enlarged clitoris with a penis bone. Morphopathological analyses performed in three of the four cases showed the presence of testes in two cases and ovotestis in another. Conventional and R-banded cytogenetic techniques were applied showing that no chromosome abnormalities were involved in these DSDs. CGH arrays show the presence of 11 copy number variations (CNVs), one of which is a duplication of 458 Kb comprising the genomic region between base 17,503,928 and base 17,962,221 of chromosome 9 (CanFam3 genome assembly). This CNV, confirmed also by qPCR, includes the promoter region of SOX9 gene and could explain the observed phenotype.

COG6-CDG: Expanding the phenotype with emphasis on glycosylation defects involved in the causation of male disorders of sex development

COG6-congenital disorder of glycosylation (COG6-CDG) is caused by biallelic mutations in COG6. To-date, 12 variants causing COG6-CDG in less than 20 patients have been reported. Using whole exome sequencing we identified two siblings with a novel homozygous deletion of 26 bp in COG6, creating a splicing variant (c.518_540 + 3del) and a shift in the reading frame. The phenotype of COG6-CDG includes growth and developmental retardation, microcephaly, liver and gastrointestinal disease, hypohydrosis and recurrent infections. We report two patients with novel phenotypic features including bowel malrotation and ambiguous genitalia, directing attention to the role of glycoprotein metabolism in the causation of disorders of sex development (DSD). Searching the glycomic literature, we identified 14 CDGs including males with DSD, a feature not previously accentuated. This study broadens the genetic and phenotypic spectrum of COG6-CDG and calls for increasing awareness to the central role of glycosylation processes in development of human sex and genitalia.

Cytogenetic Analyses in Ewes with Congenital Abnormalities of the Genital Apparatus

Simple Summary

The disorders of sex development (DSDs) are congenital conditions characterized by inconsistency among chromosomal, gonadal, and anatomical sex development. Reproduction and prolificacy are two main parameters in the sheep industry; thus, DSDs in sheep are very detrimental. Interestingly, no DSDs-associated gene mutations have been reported in sheep so far, probably due to the fact that affected animals are not detected and studied. With the aim to deepen the knowledge about DSDs in sheep and improve diagnostic tools, screening of a sheep farm aimed to detect and study DSDs in ovine species has been started, and the actual findings relative to the first two sheep flocks analysed are reported here. In our opinion, this study demonstrates that, despite the low number of studies on ovine DSDs, if compared with other species, this problem is actually present and needs more attention.

Abstract

The Disorders of Sex Development (DSDs) are congenital conditions characterized by inconsistency among chromosomal, gonadal, and anatomical sex development. The aim of this research is to report the clinical and cytogenetic findings of four DSD cases and 13 couples of heterosexual twins in sheep. To this purpose, C- and R-banding techniques were used, and the analyses of the SRY (Sex Determining Region Y) and AMEL (Amelogenin) genes were carried out. Moreover, morphopathological analyses were performed in one case. The four DSD sheep cases were registered as females at birth, and for none of them it was possible to establish whether the subjects were born from heterosexual multiple births. Three of the four cases were diagnosed as XX/XY blood lymphocyte chimaeras, while the fourth case was diagnosed as a 54, XY SRY-positive DSD sheep. None of the heterosexual twins showed XX/XY blood chimaerism. This finding suggests that the blood chimaeric cases detected could also be due to a zygote/embryo fusion. Moreover, no gene variants involved in sheep DSD are known, the identification of which would be very useful for the sheep industry.

Technical note: Droplet digital PCR as a new molecular method for a simple and reliable diagnosis of freemartinism in cattle

Freemartinism is the most common type of disorder of sex development in cattle. It leads to sterility in the female co-twin in heterosexual twin pregnancy, and is thus a serious problem in cattle production. The incidence of freemartin syndrome is directly dependent on the prevalence of twinning, which has increased in dairy cattle populations in recent years. Thus, early and rapid identification of freemartins is needed to reduce economic loss. Of the various methods used to diagnose this condition, identifying the XX and XY cell lines in blood samples using cytogenetic techniques is the gold standard; however, this technique is time consuming. Faster and more reliable techniques are thus being sought. Droplet digital PCR (ddPCR) is a third-generation PCR method and it has not previously been used to detect XX/XY leukocyte chimerism in cattle. The aim of the present study was to verify the usefulness of ddPCR to detect and quantify leukocyte chimerism in this species. The X and Y copy numbers were estimated by identifying the copy numbers of 2 genes located on the sex chromosomes: amelogenin X-linked (AMELX) on the X chromosome and amelogenin Y-linked (AMELY) on the Y chromosome. In the first step, we performed ddPCR on samples prepared from female DNA mixed with male DNA in serially diluted proportions. We determined that the sensitivity of this method was sufficient to detect a low-frequency (<5%) cell line. In the next step, ddPCR was used to analyze 22 Holstein Friesian freemartins. Cytogenetic evaluation of these cases revealed leukocyte chimerism; the proportion of XX and XY metaphase spreads varied over a wide range, from XX (98%)/XY (2%) to XX (4%)/XY (96%). The use of ddPCR facilitated the precise estimation of the ratio of the copy number of X to Y sex chromosomes. In all cases, the XX/XY chimerism detected by cytogenetic analysis was confirmed using ddPCR. The method turned out to be very simple, accurate, and sensitive. In conclusion, we recommend the ddPCR method for fast and reliable detection of XX/XY leukocyte chimerism in cattle.

Management of disorders of sex development - With a focus on development of the child and adolescent through the pubertal years

Disorders of sex development, congenital conditions in which chromosomal, gonadal or anatomic sex is atypical at birth, require urgent assessment by a multidisciplinary team, to define whether there is a life threatening disorder of congenital adrenal hyperplasia or a healthy child with a complex condition. Uncertainty, stigma and taboo complicate counselling which must be knowledgeable, comprehensive and sensitive to different circumstances, religions and cultures. This articles will discuss clinical and genetic diagnosis, decisions regarding sex of rearing, ethical dilemmas, medical management of the infant and of the child or adolescent presenting for the first time with a DSD. Surgical options, timing and management are outlined.

Molecular genetics of hypospadias and cryptorchidism recent developments

During the last decade, a tremendous amount of work has been devoted to the study of the molecular genetics of isolated hypospadias and cryptorchidism, two minor forms of disorders of sex development (DSD). Beyond the genes involved in gonadal determination and sex differentiation, including those underlying androgen biosynthesis and signaling, new genes have been identified through genome-wide association study and familial clustering. Even if no single genetic defect can explain the whole spectrum of DSD, these recent studies reinforce the strong role of the genetic background in the occurrence of these defects. The timing of signaling disruption may explain the different phenotypes.

Androgen insensitivity syndrome

Androgen insensitivity syndrome (AIS) results from androgen receptor dysfunction and is a common cause of disorder of sex development. The AIS phenotype largely depends on the degree of residual androgen receptor (AR) activity. This review describes the molecular action of androgens and the range of androgen receptor gene mutations, essential knowledge to understand the pathogenesis of the complete and partial forms of this syndrome. A multidisciplinary approach is recommended for clinical management from infancy through to adulthood. Hormone replacement therapy is needed following gonadectomy. Patients who choose to retain the gonads are at risk of developing germ cell tumors for which sensitive circulating tumor markers may soon become available. Whilst the contribution of AR dysfunction to complete AIS is well understood, the involvement of the AR and associated proteins as contributors to partial AIS is an area of active research. Disorders of sex development such as AIS which are related to AR dysfunction offer a breadth of manifestations for the clinician to manage and opportunities for further research on the mechanism of androgen action.