Management of a girl with delayed puberty and elevated gonadotropins

A girl presenting with delayed puberty and elevated gonadotropins may have a range of conditions such as Turner Syndrome (TS), Primary Ovarian Insufficiency (POI) and 46,XY DSD. An organized and measured approach to investigation can help reach a timely diagnosis. Management of young people often requires specialist multidisciplinary input to address the endocrine and non-endocrine features of these complex conditions, as well as the psychological challenges posed by their diagnosis. Next generation sequencing within the research setting has revealed several genetic causes of POI and 46,XY DSD which may further facilitate an individualized approach to care of these young people in the future. Pubertal induction is required in many and the timing of this may need to be balanced with other issues specific to the condition (e.g., allowing time for information-sharing in 46,XY DSD, optimizing growth in TS). Shared decision-making and sign-posting to relevant support groups from the outset can help empower young people and their families to manage these conditions. We describe three clinical vignettes of girls presenting with delayed puberty and hypergonadotropic amenorrhea and discuss their clinical management in the context of current literature and guidelines

ZSWIM7 Is associated with human female meiosis and familial primary ovarian insufficiency

Background Primary ovarian insufficiency (POI) affects 1% of women and is associated with significant medical consequences. A genetic cause for POI can be found in up to 30% of women, elucidating key roles for these genes in human ovary development. Objective We aimed to identify the genetic mechanism underlying early-onset POI in 2 sisters from a consanguineous pedigree. Methods Genome sequencing and variant filtering using an autosomal recessive model was performed in the 2 affected sisters and their unaffected family members. Quantitative reverse transcriptase PCR (qRT-PCR) and RNA sequencing were used to study the expression of key genes at critical stages of human fetal gonad development (Carnegie Stage 22/23, 9 weeks post conception (wpc), 11 wpc, 15/16 wpc, 19/20 wpc) and in adult tissue. Results Only 1 homozygous variant cosegregating with the POI phenotype was found: a single nucleotide substitution in zinc finger SWIM-type containing 7 (ZSWIM7), NM_001042697.2: c.173C > G; resulting in predicted loss-of-function p.(Ser58*). qRT-PCR demonstrated higher expression of ZSWIM7 in the 15/16 wpc ovary compared with testis, corresponding to peak meiosis in the fetal ovary. RNA sequencing of fetal gonad samples showed that ZSWIM7 has a similar temporal expression profile in the developing ovary to other homologous recombination genes. Main conclusions Disruption of ZSWIM7 is associated with POI in humans. ZSWIM7 is likely to be important for human homologous recombination; these findings expand the range of genes associated with POI in women

Pathogenic variants in the human m(6)A 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 meiosisassociated 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

Genetic mechanisms of human ovary development and function: A life course approach

Adult ovary function requires appropriate gonad development, folliculogenesis, and oogenesis, which all begin in fetal life. Genetic mechanisms underlying these processes are interrelated and, when disrupted, result in primary ovarian insufficiency (POI). POI is early-onset in 10% (EO-POI), presenting with primary amenorrhoea or pubertal failure. Clinically, a genetic cause is currently seldom sought. Developing new treatments requires improved molecular insight on an individual basis. Here, several complementary studies are presented with impact for understanding ovarian function across the lifecourse. Firstly, a bulk RNAseq time-series transcriptomic analysis of developing human ovary, testes, and control samples (n=47, four stages between 7/8 and 15/16 weeks post conception) was combined with single-nuclei RNA sequencing (snRNAseq) of two 46,XX ovaries. The fetal ovary was transcriptomically distinct from testis and enriched for specific subsets of nuclear receptors, transcription factors, and meiotic genes. New candidate genes (e.g. meiotic pathways) and novel regulatory networks (e.g. neuroendocrine signaling) were identified. Secondly, X chromosome gene expression was examined. Enrichment of X chromosome genes was seen, particularly those escaping X-inactivation. snRNAseq analysis, including two 45,X ovaries, suggested mechanisms of ovarian dysfunction in Turner Syndrome beyond X chromosome asynapsis: dysregulated proteostasis, mitochondrial insufficiency, and abnormal methylation. Thirdly, exome sequencing of women with EO-POI (n=149) established a molecular aetiology in 29.7% with sporadic POI and 58.8% of kindred with familial POI. A further 30.5% women had a potential genetic aetiology identified. POI was heterogeneous genetically, with pathogenic variants in 73 genes identified and frequent polygenicity. The DNA repair gene, ZSWIM7, and RNA helicase, YTHDC2, were studied in detail and identified as novel causes of POI. Taken together, this work demonstrates a remarkably complex genetic landscape of fetal ovary development and ovarian insufficiency in humans. It highlights the value of integrating genetic analysis in a clinical context with transcriptomic data and suggests directions for future work