Two Novel Pathogenic Variants Confirm RMND1 Causative Role in Perrault Syndrome with Renal Involvement.

RMND1 (required for meiotic nuclear division 1 homolog) pathogenic variants are known to cause combined oxidative phosphorylation deficiency (COXPD11), a severe multisystem disorder. In one patient, a homozygous RMND1 pathogenic variant, with an established role in COXPD11, was associated with a Perrault-like syndrome. We performed a thorough clinical investigation and applied a targeted multigene hearing loss panel to reveal the cause of hearing loss, ovarian dysfunction (two cardinal features of Perrault syndrome) and chronic kidney disease in two adult female siblings. Two compound heterozygous missense variants, c.583G>A (p.Gly195Arg) and c.818A>C (p.Tyr273Ser), not previously associated with disease, were identified in RMND1 in both patients, and their segregation with disease was confirmed in family members. The patients have no neurological or intellectual impairment, and nephrological evaluation predicts a benign course of kidney disease. Our study presents the mildest, so far reported, RMND1-related phenotype and delivers the first independent confirmation that RMND1 is causally involved in the development of Perrault syndrome with renal involvement. This highlights the importance of including RMND1 to the list of Perrault syndrome causative factors and provides new insight into the clinical manifestation of RMND1 deficiency.

Perrault syndrome is caused by recessive mutations in CLPP, encoding a mitochondrial ATP-dependent chambered protease.

Perrault syndrome is a genetically and clinically heterogeneous autosomal-recessive condition characterized by sensorineural hearing loss and ovarian failure. By a combination of linkage analysis, homozygosity mapping, and exome sequencing in three families, we identified mutations in CLPP as the likely cause of this phenotype. In each family, affected individuals were homozygous for a different pathogenic CLPP allele: c.433A>C (p.Thr145Pro), c.440G>C (p.Cys147Ser), or an experimentally demonstrated splice-donor-site mutation, c.270+4A>G. CLPP, a component of a mitochondrial ATP-dependent proteolytic complex, is a highly conserved endopeptidase encoded by CLPP and forms an element of the evolutionarily ancient mitochondrial unfolded-protein response (UPR(mt)) stress signaling pathway. Crystal-structure modeling suggests that both substitutions would alter the structure of the CLPP barrel chamber that captures unfolded proteins and exposes them to proteolysis. Together with the previous identification of mutations in HARS2, encoding mitochondrial histidyl-tRNA synthetase, mutations in CLPP expose dysfunction of mitochondrial protein homeostasis as a cause of Perrault syndrome.

46,XX DSD: the masculinised female.

The 46,XX disorders of sex development (DSDs) cause virilisation or masculinisation of the female foetus. The final common pathway of all 46,XX DSDs is excess dihydrotestosterone (DHT) or potent foreign androgen in the genital tissue during the critical period of sexual differentiation. Whereas the foetal testis is source of androgen in the male, it is the foetal adrenal that produces the DHT precursors in the female. By understanding the principles of human steroid biosynthesis, the pathogenesis of each disorder may be logically deduced, and treatment strategies are rationally constructed. In practice, however, therapies for many of these diseases are fraught with complications and caveats, and current approaches leave much room for improvement. This review discusses these diseases, their pathogenesis and approaches to therapy. We emphasise areas where improved treatments are sorely needed.

Three out of four: a case discussion on ambiguous genitalia.

Disorders of sex development (DSD) include a heterogeneous group of heritable disorders of sex determination and differentiation. This includes chromosomal as well as monogenic disorders, which inhibit or change primarily genetic or endocrine pathways of normal sex development. However, in many patients affected, no definitive cause for the disorder can be found. Therefore, the birth of a child with ambiguous genitalia still represents an enormous challenge. For the structuring of diagnostic procedures, decision making and also therapeutic interventions, a highly specialised team of physicians of different subspecialties and experts for psychosocial care is needed to counsel parents and patients accordingly. This article presents a case with 46,XX DSD and androgen excess. After making the diagnosis on clinical and biochemical grounds, the family refused further genetic testing. The outcome of subsequent pregnancies confirmed the working diagnosis of an autosomal form of 46,XX DSD. However, the family still refused prenatal testing and treatment on religious grounds. The case discussion further illuminates the possible influence of religion in prenatal testing and concludes with the approach to the parents for comprehensive counselling in decision making for their child.

Predictive value of anatomical findings and karyotype analysis in the diagnosis of patients with disorders of sexual development.

We assessed the predictive value of anatomical findings and karyotype for establishing a diagnostic orientation in patients with disorders of sex development (DSD). We performed a retrospective chart analysis of 228 patients, grouped into 4 categories: 46,XX DSD, non-dysgenetic testicular DSD, dysgenetic testicular DSD and ovotesticular DSD. Degree of virilisation, presence of vagina, presence of palpable gonads, size of gonads and a plain karyotype was available for all cases. 46,XX DSD due to congenital adrenal hyperplasia counted for 59.2% of the cases, non-dysgenetic testicular DSD for 13.6%, dysgenetic testicular DSD for 21.5% and ovotesticular DSD for 5.7%. Excluding congenital adrenal hyperplasia (CAH), a karyotype with at least one 46,XX cell line had a high diagnostic efficiency for ovotesticular DSD. In these patients, anatomical findings were not as useful to predict the gonadal phenotype. The existence of a 45,X cell line predicted with very high efficiency dysgenetic testicular DSD. Genital palpation was only partially helpful to predict the existence of testicular tissue. Non-dysgenetic testicular DSD could be ruled out with high efficiency in patients with an abnormal karyotype. Anatomical findings were helpful in 46,XY patients: palpated masses predicted non-dysgenetic testes with high accuracy. In all cases assessment of gonadal volume was less useful.

[XY type gonadal dysgenesis, trisomy X and variants].

Sex determination and differentiation depend on differentiation of the indifferent gonad to the testis or ovary, which leads to masculine or feminine differentiation of internal and external genitalia. Recently, genes involved in this cascade have been identified with the advance of molecular genetical analysis. XY gonadal dysgenesis, this is a condition that has XY chromosome but is characterized by the indifferent testis. There are complete and incomplete types. Complete type has bilateral gonads of cordee, does not show physical characteristics of Turner's syndrome, has the uterus and ovaries, and has the vagina in female type, though the external genitalia are immature. Incomplete type is characterized by bilateral testicular hypoplasia(male pseudohermaphroditism) or unilateral testicular hypoplasia and bilateral restiform gonads(mixed gonadal dyspenesis), and the sexuality of the external genitalia is unclear. XX gonadal dysgenesis, complete type is characterized by bilateral restiform gonads, female type internal and external genitalia and sexual immaturity, though it does not show any characteristics of Turner's syndrome. It presents hypergonadotropic hypogonadism endocrinologically. It shows a familial incidence with autosomal recessive inheritance, and sensorineural deafness is accompanied in some cases. Incomplete type has rudimentary ovaries and show a varying degree of secondary sexual characteristics. Mixed dysgenesis, many cases have XO/XY mosaic and this dysgenesis is characterized by unilateral hypoplastic testis and contralateral restiform gonad. It may occur in cases of incomplete type XY gonadal dysgenesis. Trisomy X, cases of trisomy X have three X chromosomes as this term indicates. There are some cases of polisomy with four or more X chromosomes. The frequency of trisomy X has been reported to be one in 1,000 births of female, which means that it is a relatively common chromosomal aberration. It has been reported that about 20% of cases of trisomy X have sexual dysfunction, predominantly with primary amenorrha.

Feminizing genitoplasty in patients with 46XX congenital adrenal hyperplasia.

Congenital adrenal hyperplasia (CAH) is the most common cause of ambiguous genitalia in newborns. This paper is based upon review of the literature and personal experience. We focus upon the surgical anatomy, pre-operative evaluation, including imaging, mainly by transabdominal ultrasound, and upon the goals and the history of surgical reconstruction. The various surgical techniques are mentioned with a detailed description of our technique used in 52 patients. The timing and staging of the operation and the implications of prenatal therapy are discussed. In conclusion, we believe that infants with 46XX CAH can undergo one-stage feminizing genitoplasty very early in life with satisfactory cosmetic and functional results.