An integrated single-cell analysis of human adrenal cortex development.

The adrenal glands synthesize and release essential steroid hormones such as cortisol and aldosterone, but many aspects of human adrenal gland development are not well understood. Here, we combined single-cell and bulk RNA sequencing, spatial transcriptomics, IHC, and micro-focus computed tomography to investigate key aspects of adrenal development in the first 20 weeks of gestation. We demonstrate rapid adrenal growth and vascularization, with more cell division in the outer definitive zone (DZ). Steroidogenic pathways favored androgen synthesis in the central fetal zone, but DZ capacity to synthesize cortisol and aldosterone developed with time. Core transcriptional regulators were identified, with localized expression of HOPX (also known as Hop homeobox/homeobox-only protein) in the DZ. Potential ligand-receptor interactions between mesenchyme and adrenal cortex were seen (e.g., RSPO3/LGR4). Growth-promoting imprinted genes were enriched in the developing cortex (e.g., IGF2, PEG3). These findings reveal aspects of human adrenal development and have clinical implications for understanding primary adrenal insufficiency and related postnatal adrenal disorders, such as adrenal tumor development, steroid disorders, and neonatal stress.

Pathogenic variants in the human m6A reader YTHDC2 are associated with primary ovarian insufficiency.

Primary ovarian insufficiency (POI) affects 1% of women and carries significant medical and psychosocial sequelae. Approximately 10% of POI has a defined genetic cause, with most implicated genes relating to biological processes involved in early fetal ovary development and function. Recently, Ythdc2, an RNA helicase and N6-methyladenosine reader, has emerged as a regulator of meiosis in mice. Here, we describe homozygous pathogenic variants in YTHDC2 in 3 women with early-onset POI from 2 families: c. 2567C>G, p.P856R in the helicase-associated (HA2) domain and c.1129G>T, p.E377*. We demonstrated that YTHDC2 is expressed in the developing human fetal ovary and is upregulated in meiotic germ cells, together with related meiosis-associated factors. The p.P856R variant resulted in a less flexible protein that likely disrupted downstream conformational kinetics of the HA2 domain, whereas the p.E377* variant truncated the helicase core. Taken together, our results reveal that YTHDC2 is a key regulator of meiosis in humans and pathogenic variants within this gene are associated with POI.

Clinical and genetic heterogeneity of HNF4A/HNF1A mutations in a multicentre paediatric cohort with hyperinsulinaemic hypoglycaemia.

OBJECTIVE: The phenotype mediated by HNF4A/HNF1A mutations is variable and includes diazoxide-responsive hyperinsulinaemic hypoglycaemia (HH) and maturity-onset diabetes of the young (MODY). DESIGN: We characterised an international multicentre paediatric cohort of patients with HNF4Aor HNF1Amutations presenting with HH over a 25-year period (1995-2020). METHODS: Clinical and genetic analysis data from five centres were obtained. Diazoxide responsiveness was defined as the ability to maintain normoglycaemia without intravenous glucose. Macrosomia was defined as a birth weight ≥90th centile. SPSS v.27.1 was used for data analysis. RESULTS: A total of 34 patients (70.6% female, n = 24) with a mean age of 7.1 years (s.d. 6.4) were included. A total of 21 different heterozygous HNF4Amutations were identified in 29 patients (four novels). Four different previously described heterozygous HNF1A mutations were detected in five patients. Most (97.1%, n = 33) developed hypoglycaemia by day 2 of life. The mean birth weight was 3.8 kg (s.d. 0.8), with most infants macrosomic (n = 21, 61.8%). Diazoxide was commenced in 28 patients (82.3%); all responded. HH resolved in 20 patients (58.8%) following a median of 0.9 years (interquartile range (IQR): 0.2-6.8). Nine patients (n = 9, 26.5%) had developmental delay. Two patients developed Fanconi syndrome (p.Arg63Trp, HNF4A) and four had other renal or hepatic findings. Five (14.7%) developed MODY at a median of 11.0 years (IQR: 9.0-13.9). Of patients with inherited mutations (n = 25, 73.5%), a family history of diabetes was present in 22 (88.0%). CONCLUSIONS: We build on the knowledge of the natural history and pancreatic and extra-pancreatic phenotypes of HNF4A/HNF1Amutations and illustrate the heterogeneity of this condition.

Pathogenic variants in RNPC3 are associated with hypopituitarism and primary ovarian insufficiency.

PURPOSE: We aimed to investigate the molecular basis underlying a novel phenotype including hypopituitarism associated with primary ovarian insufficiency. METHODS: We used next-generation sequencing to identify variants in all pedigrees. Expression of Rnpc3/RNPC3 was analyzed by in situ hybridization on murine/human embryonic sections. CRISPR/Cas9 was used to generate mice carrying the p.Leu483Phe pathogenic variant in the conserved murine Rnpc3 RRM2 domain. RESULTS: We described 15 patients from 9 pedigrees with biallelic pathogenic variants in RNPC3, encoding a specific protein component of the minor spliceosome, which is associated with a hypopituitary phenotype, including severe growth hormone (GH) deficiency, hypoprolactinemia, variable thyrotropin (also known as thyroid-stimulating hormone) deficiency, and anterior pituitary hypoplasia. Primary ovarian insufficiency was diagnosed in 8 of 9 affected females, whereas males had normal gonadal function. In addition, 2 affected males displayed normal growth when off GH treatment despite severe biochemical GH deficiency. In both mouse and human embryos, Rnpc3/RNPC3 was expressed in the developing forebrain, including the hypothalamus and Rathke's pouch. Female Rnpc3 mutant mice displayed a reduction in pituitary GH content but with no reproductive impairment in young mice. Male mice exhibited no obvious phenotype. CONCLUSION: Our findings suggest novel insights into the role of RNPC3 in female-specific gonadal function and emphasize a critical role for the minor spliceosome in pituitary and ovarian development and function.

Premature ovarian insufficiency.

The natural lifespan of the ovary is occasionally interrupted by pathological processes; some are known, but many are unknown. Premature ovarian insufficiency (POI) can be a devastating diagnosis for an adolescent or for someone who has yet to start a family. Common causes of POI include genetic and chromosomal defects, autoimmune damage, and cancer treatments. Knowledge of the pathogenesis of this condition and an awareness of contemporary hormone replacement and fertility options are required to design a multidisciplinary therapeutic approach comprising reproductive medicine, endocrinology, clinical psychology, and assisted fertility expertise.

Mosaic PRKACA duplication causing a novel and distinct phenotype of early-onset Cushing's syndrome and acral cutaneous mucinosis.

SIGNIFICANCE STATEMENT: We describe a mosaic PRKACA duplication in a young infant who presented with a Carney-like complex: bilateral non-pigmented micronodular adrenal hyperplasia, severe early-onset Cushing's syndrome, and distinct acral soft tissue overgrowth due to cutaneous mucinosis. This represents a novel manifestation of PRKACA disruption and broadens the extra-adrenal phenotype of PRKACA-associated Cushing's syndrome. Our data suggest that Cushing's syndrome phenotypes arising from somatic and germline PRKACA abnormalities can exist on a spectrum. We emphasise the value of ascertaining a genetic diagnosis for PRKACA-mediated adrenal and extra-adrenal disease to guide individualised and targeted care.