Knockout mice with pituitary malformations help identify human cases of hypopituitarism.

BACKGROUND: Congenital hypopituitarism (CH) and its associated syndromes, septo-optic dysplasia (SOD) and holoprosencephaly (HPE), are midline defects that cause significant morbidity for affected people. Variants in 67 genes are associated with CH, but a vast majority of CH cases lack a genetic diagnosis. Whole exome and whole genome sequencing of CH patients identifies sequence variants in genes known to cause CH, and in new candidate genes, but many of these are variants of uncertain significance (VUS). METHODS: The International Mouse Phenotyping Consortium (IMPC) is an effort to establish gene function by knocking-out all genes in the mouse genome and generating corresponding phenotype data. We used mouse embryonic imaging data generated by the Deciphering Mechanisms of Developmental Disorders (DMDD) project to screen 209 embryonic lethal and sub-viable knockout mouse lines for pituitary malformations. RESULTS: Of the 209 knockout mouse lines, we identified 51 that have embryonic pituitary malformations. These genes not only represent new candidates for CH, but also reveal new molecular pathways not previously associated with pituitary organogenesis. We used this list of candidate genes to mine whole exome sequencing data of a cohort of patients with CH, and we identified variants in two unrelated cases for two genes, MORC2 and SETD5, with CH and other syndromic features. CONCLUSIONS: The screening and analysis of IMPC phenotyping data provide proof-of-principle that recessive lethal mouse mutants generated by the knockout mouse project are an excellent source of candidate genes for congenital hypopituitarism in children.

Pituitary stalk interruption syndrome due to novel ROBO1 mutation presenting as combined pituitary hormone deficiency and central diabetes insipidus.

OBJECTIVES: The genetic causes of pituitary stalk interruption syndrome (PSIS) remain elusive in 95 % of cases. The roundabout receptor-1 gene (ROBO1) plays critical roles in axonal guidance and cell migration. Recently, mutations in the ROBO1 gene have been reported patients with PSIS. CASE PRESENTATION: We report a 2.9-year-old boy with PSIS who presented with combined pituitary hormone deficiency, central diabetes insipidus, and the classical triad of MRI findings. Through clinical exome sequencing using next-generation sequencing techniques, a previously unidentified novel heterozygous frame shift mutation in the ROBO1 gene was identified. This is the first report of ROBO1 mutation associated with posterior pituitary dysfunction. CONCLUSIONS: We conclude and emphasize that ROBO1 should be investigated in patients with PSIS. Our case is unique in the published literature in that we are first time reporting posterior pituitary dysfunction as manifestation of ROBO1 mutation. The full clinical spectrum of the mutations may not be fully known.

Re-analysis of gene mutations found in pituitary stalk interruption syndrome and a new hypothesis on the etiology.

Background: Pituitary stalk interruption syndrome (PSIS) is a complex clinical syndrome characterized by varied pituitary hormone deficiencies, leading to severe manifestations across multiple systems. These include lifelong infertility, short stature, mental retardation, and potentially life-threatening pituitary crises if not promptly diagnosed and treated. Despite extensive research, the precise pathogenesis of PSIS remains unclear. Currently, there are two proposed theories regarding the pathogenic mechanisms: the genetic defect theory and the perinatal injury theory. Methods: We systematically searched English databases (PubMed, Web of Science, Embase) and Chinese databases (CNKI, WanFang Med Online, Sinomed) up to February 24, 2023, to summarize studies on gene sequencing in PSIS patients. Enrichment analyses of reported mutated genes were subsequently performed using the Metascape platform. Results: Our study included 37 articles. KEGG enrichment analysis revealed mutated genes were enriched in the Notch signaling pathway, Wnt signaling pathway, and Hedgehog signaling pathway. GO enrichment analysis demonstrated mutated genes were enriched in biological processes such as embryonic development, brain development, axon development and guidance, and development of other organs. Conclusion: Based on our summary and analyses, we propose a new hypothesis: disruptions in normal embryonic development, partially stemming from the genetic background and/or specific gene mutations in individuals, may increase the likelihood of abnormal fetal deliveries, where different degrees of traction during delivery may lead to different levels of pituitary stalk interruption and posterior lobe ectopia. The clinical diversity observed in PSIS patients may result from a combination of genetic background, specific mutations, and variable degrees of traction during delivery.

SEC31A may be associated with pituitary hormone deficiency and gonadal dysgenesis.

PURPOSE: Disorders/differences of sex development (DSD) result from variants in many different human genes but, frequently, have no detectable molecular cause. METHODS: Detailed clinical and genetic phenotyping was conducted on a family with three children. A Sec31a animal model and functional studies were used to investigate the significance of the findings. RESULTS: By trio whole-exome DNA sequencing we detected a heterozygous de novo nonsense SEC31A variant, in three children of healthy non-consanguineous parents. The children had different combinations of disorders that included complete gonadal dysgenesis and multiple pituitary hormone deficiency. SEC31A encodes a component of the COPII coat protein complex, necessary for intracellular anterograde vesicle-mediated transport between the endoplasmic reticulum (ER) and Golgi. CRISPR-Cas9 targeted knockout of the orthologous Sec31a gene region resulted in early embryonic lethality in homozygous mice. mRNA expression of ER-stress genes ATF4 and CHOP was increased in the children, suggesting defective protein transport. The pLI score of the gene, from gnomAD data, is 0.02. CONCLUSIONS: SEC31A might underlie a previously unrecognised clinical syndrome comprising gonadal dysgenesis, multiple pituitary hormone deficiencies, dysmorphic features and developmental delay. However, a variant that remains undetected, in a different gene, may alternatively be causal in this family.

A Novel RNPC3 Gene Variant Expands the Phenotype in Patients with Congenital Hypopituitarism and Neuropathy.

INTRODUCTION: Pathogenic biallelic RNPC3 variants cause congenital hypopituitarism (CH) with congenital cataracts, neuropathy, developmental delay/intellectual disability, primary ovarian insufficiency, and pituitary hypoplasia. Here, we aimed to evaluate the clinical and molecular characteristics of 2 patients with CH and neuropathy. MATERIALS AND METHODS: Proband was evaluated by clinical, laboratory, and radiological exams, followed by exome sequencing (ES). Clinical investigation of an affected sibling and variant segregation in the family was performed by Sanger sequencing. A three-dimensional protein model study was conducted to predict the effect of the variant on the function of the RNPC3 peptide. RESULTS: Proband was a 16-month-old girl who was referred for the evaluation of failure to thrive. Her height, weight, and head circumference were 55.8 cm (-7.6 SDS), 6.5 kg (-3.6 SDS), and 41.8 cm (-3.82), respectively. She had a developmental delay and intellectual disability. Central hypothyroidism, growth hormone, and prolactin deficiencies were identified, and MRI revealed pituitary hypoplasia. Electroneuromyography performed for the gait abnormality revealed peripheral neuropathy. A homozygous novel variant c.484C>T/p.(Pro162Ser) in the RNPC3 was detected in the ES. Her brother had the same genotype, and he similarly had pituitary hormone deficiencies with polyneuropathy. CONCLUSION: Expanding our knowledge of the spectrum of RNPC3 variants, and apprehending clinical and molecular data of additional cases, is decisive for accurate diagnosis and genetic counseling.

SALL4 Phenotype in Four Generations of One Family: An Interplay of the Upper Limb, Kidneys, and the Pituitary.

INTRODUCTION: The SALL4 gene encodes a transcription factor that is essential for early embryonic cellular differentiation of the epiblast and primitive endoderm. It is required for the development of neural tissue, kidney, heart, and limbs. Pathogenic SALL4 variants cause Duane-radial ray syndrome (Okihiro syndrome), acro-renal-ocular syndrome, and Holt-Oram syndrome. We report a family with vertical transmission of a SALL4 pathogenic variant leading to radial hypoplasia and kidney dystopia in several generations with additional growth hormone deficiency (GHD) in the proband. CASE PRESENTATION: Our male proband was born at the 39th week of gestation. He was born small for gestational age (SGA; birth weight 2,550 g, -2.2 SDS; length 47 cm, -2.0 SDS). He had bilateral asymmetrical radial ray malformation (consisting of radial hypoplasia, ulnar flexure, and bilateral aplasia of the thumb) and pelvic kidney dystopia, but no cardiac malformations, clubfoot, ocular coloboma, or Duane anomaly. He was examined for progressive short stature at the age of 3.9 years, where his IGF-1 was 68 µg/L (-1.0 SD), and growth hormone (GH) after stimulation 6.2 µg/L. Other pituitary hormones were normal. A brain CT revealed normal morphology of the cerebral midline and the pituitary. He had a dental anomaly - a central mandibular ectopic canine. MRI could not be done due to the presence of metal after multiple corrective plastic surgeries of his hands. His mother's and father's heights are 152.3 cm (-2.4 SD) and 177.8 cm (-0.4 SD), respectively. His father has a milder malformation of the forearm. The affected paternal grandfather (height 164 cm; -2.3 SD) has a radial ray defect with missing opposition of the thumb. The family reports a similar phenotype of radial dysplasia in the paternal grandfather's mother. The proband started GH therapy at age 6.5 years when his height was 109 cm (-2.8 SDS) and he experienced catch-up growth as expected in GHD. Puberty started spontaneously at the age of 12.5 years. At age 13, his height was 158.7 cm (-0.2 SDS). Whole-exome sequencing revealed a nonsense variant in the SALL4 gene c.1717C>T (p.Arg573Ter) in the proband, his father, and paternal grandfather. CONCLUSION: This is the first observation of a patient with a congenital upper limb defect due to a pathogenic SALL4 variant who has isolated GHD with no apparent cerebral or facial midline anomaly and has been successfully treated with growth hormone.

Phenotype-Genotype Correlations of GH1 Gene Variants in Patients with Isolated Growth Hormone Deficiency or Multiple Pituitary Hormone Deficiency.

INTRODUCTION: Genetic forms of growth hormone deficiency (GHD) may occur as isolated GHD (IGHD) or as a component of multiple pituitary hormone deficiency (MPHD). This study aimed to present the clinical and molecular characteristics of patients with IGHD/MPHD due to the GH1 gene variants. METHODS: A gene panel accommodating 25 genes associated with MPHD and short stature was used to search for small sequence variants. Multiplex ligation-dependent probe amplification was performed in patients with normal panel results to investigate gross deletion/duplications. Segregation in the family was performed by Sanger sequencing. RESULTS: The GH1 gene variants were detected in 5 patients from four unrelated families. One patient had IGHD IA due to homozygous whole GH1 gene deletion and one had IGHD IB due to novel homozygous c.162C>G/p.(Tyr54*) variant. Two patients from a family had previously reported heterozygous c.291+1G>A/p.(?) variant in which clinical and genetic characteristics were compatible with IGHD II accompanying MPHD. One patient had clinical and laboratory characteristics of IGHD II with MPHD but the heterozygous c.468 C>T/p.(R160W) variant had conflicting results about the relationship with the phenotype. CONCLUSION: Expanding our knowledge of the spectrum of GH1 gene variants by apprehending clinical and molecular data of more cases, helps to identify the genotype-phenotype correlation of IGHD/MPHD and the GH1 gene variants. These patients must be regularly followed up for the occurrence of additional pituitary hormone deficiencies.

Exome sequencing in 16 patients with pituitary stalk interruption syndrome: A monocentric study.

Pituitary stalk interruption syndrome (PSIS) is a rare disorder characterized by an absent or ectopic posterior pituitary, absent or interrupted pituitary stalk and anterior pituitary hypoplasia on magnetic resonance imaging (MRI), as well in some cases a range of heterogeneous somatic anomalies. The triad can be incomplete. Here, we performed exome sequencing on 16 sporadic patients, aged 0.4 to 13.7 years diagnosed with isolated or complex PSIS. Growth hormone deficiency was isolated in 10 cases, or associated with thyrotropin deficiency in 6 others (isolated (2 cases), associated with adrenocorticotropin deficiency (1 case), gonadotropins deficiency (1 case), or multiple deficiencies (2 cases)). Additional phenotypic anomalies were present in six cases (37.5%) including four with ophthalmic disorders. In 13 patients variants were identified that may contribute to the phenotype. However, only a single individual carried a variant classified as pathogenic. This child presented with the typical clinical presentation of Okur-Chung neurodevelopmental syndrome due to a CSNK2A1 missense variant. We also identified variants in the holoprosencephaly associated genes GLI2 and PTCH1. A likely pathogenic novel splice site variant in the GLI2 gene was observed in a child with PSIS and megacisterna magna. In the remaining 11 cases 26 variants in genes associated with pituitary development or function were identified and were classified of unknown significance. Compared with syndromic forms the diagnostic yield in the isolated forms of PSIS is low. Although we identified rare or novel missense variants in several hypogonadotropic hypogonadism genes (e.g. FGF17, HS6ST1, KISS1R, CHD7, IL17RD) definitively linking them to the PSIS phenotype is premature. A major challenge remains to identify pathogenic variants in cases with isolated PSIS.

Genetic diagnosis of congenital hypopituitarism in Turkish patients by a target gene panel: novel pathogenic variants in GHRHR, GLI2, LHX4 and POU1F1 genes.

Objective: Congenital hypopituitarism (CH) is a rare disease characterized by one or more hormone deficiencies of the pituitary gland. To date, many genes have been associated with CH. In this study, we identified the allelic variant spectrum of 11 causative genes in Turkish patients with CH. Materials and methods: This study included 47 patients [21 girls (44.6%) and 26 boys (55.4%)] from 45 families. To identify the genetic etiology, we screened 11 candidate genes associated with CH using next-generation sequencing. To confirm and detect the status of the specific familial variant in relatives, Sanger sequencing was also performed. Results: We identified 12 possible pathogenic variants in GHRHR, GH1, GLI2, PROP-1, POU1F1, and LHX4 in 11 patients (23.4%), of which six were novel variants: two in GHRHR, two in POU1F1, one in GLI2, and one in LHX4. In all patients, these variants were most frequently found in GLI2, followed by PROP-1 and GHRHR. Conclusion: Genetic causes were determined in only 23.4% of all patients with CH and 63% of molecularly diagnosed patients (7/11) from consanguineous families. Despite advances in genetics, we were unable to identify the genetic etiology of most patients with CH, suggesting the effect of unknown genes or environmental factors. More genetic studies are necessary to understand the etiology of CH.

The benefit of rhGH therapy in a Chinese child with 12q14 microdeletion syndrome: a case report.

OBJECTIVES: The 12q14 microdeletion syndrome is a rare genetic condition characterized by intrauterine growth restriction, proportionate short stature, failure to thrive, and intellectual disability. Few reports have discussed the therapeutic aspect of patients with 12q14 microdeletion syndrome. Herein, we report the first case of 12q14 microdeletion patient treated with rhGH without growth hormone deficiency. CASE PRESENTATION: The patient presented with feeding difficulties during infancy, failure to thrive, intellectual disability and subtle dysmorphic facial features. The patient first visited the clinic at 5 years and 3 months, his height was 91.4 cm (-4.9 SD) and weight 10.0 kg (-2.86 SD). The growth hormone level was within the normal range. Bone radiological testing revealed no significant abnormalities. Genetic analysis identified a 6.97 Mb deletion at the chromosome 12q14.1-q14.3 region in the proband. Recombinant human growth hormone therapy was initiated, which lasted for 12 months, and the new height was 101.0 cm (-4.0 SD) and weight 12.0 kg (-3.6 SD). CONCLUSIONS: This report first showed that patient with 12q14 microdeletion, although without growth hormone deficiency, can benefit from human growth hormone therapy.

A case of osteogenesis imperfecta caused by a COL1A1 variant, coexisting with pituitary stalk interruption syndrome.

Osteogenesis imperfecta (OI) is a rare hereditary bone fragility disorder that affects 6-7 per 100,000 populations, and pituitary stalk interruption syndrome (PSIS) is a rare congenital defect with varying degrees of pituitary hormone deficiency, affecting approximately 0.5 in every 100,000 births. Currently, only two cases of these complications have been reported. A 46-year-old male who had experienced more than 20 fractures (peripheral and vertebral) during adolescence visited our hospital for close examination. He presented with blue sclerae and long bone deformations. We suspected OI because his mother and sister, who were being treated for osteoporosis, also had blue sclerae. Genetic testing identified a heterozygous variant (c.757C > T, p.Arg253Ter) in the COL1A1 gene, leading to the diagnosis of OI. His mother and sister also had the same variant. Considering that he underwent GH replacement therapy for his short stature during his childhood, his pituitary hormone levels were also evaluated to know if GH deficiency impacted low bone density; hypopituitarism was then suspected. The pituitary function test results led to the diagnoses of hypothalamic GH deficiency, hypogonadism, hypothyroidism, and hypoadrenocorticism. Furthermore, magnetic resonance imaging showed anterior pituitary atrophy, pituitary stalk loss, and ectopic posterior pituitary, leading to the diagnosis of PSIS. The combination of OI and hypopituitarism may have caused further bone fragility. Therefore, although rare, clinicians should keep in mind that patients with OI can possibly have concomitant pituitary insufficiency, which can lead to developmental and growth retardation.

Combined pituitary hormone deficiency harboring CHD7 gene missense mutation without CHARGE syndrome: a case report.

BACKGROUND: Heterozygous loss-of-function mutations in the chromodomain helicase DNA-binding protein 7 (CHD7) gene cause CHARGE syndrome characterized by various congenital anomalies. A majority of patients with CHARGE syndrome present with congenital hypogonadotropic hypogonadism (HH), and combined pituitary hormone deficiency (CPHD) can also be present. Whereas CHD7 mutations have been identified in some patients with isolated HH without a diagnosis of CHARGE syndrome, it remains unclear whether CHD7 mutations can be identified in patients with CPHD who do not fulfill the criteria for CHARGE syndrome. CASE PRESENTATION: A 33-year-old woman was admitted to our hospital. She had primary amenorrhea and was at Tanner stage 2 for both pubic hair and breast development. She was diagnosed with CPHD (HH, growth hormone deficiency, and central hypothyroidism), and a heterozygous rare missense mutation (c.6745G > A, p.Asp2249Asn) in the CHD7 gene was identified. Our conservation analysis and numerous in silico analyses suggested that this mutation had pathogenic potential. She had mild intellectual disability, a minor feature of CHARGE syndrome, but did not fulfill the criteria for CHARGE syndrome. CONCLUSIONS: We report a rare case of CPHD harboring CHD7 mutation without CHARGE syndrome. This case provides valuable insights into phenotypes caused by CHD7 mutations. CHD7 mutations can have a continuous phenotypic spectrum depending on the severity of hypopituitarism and CHARGE features. Therefore, we would like to propose a novel concept of CHD7-associated syndrome.

Identification of genetic variants and phenotypic characterization of a large cohort of patients with congenital hypopituitarism and related disorders.

PURPOSE: Congenital hypopituitarism (CH) disorders are phenotypically variable. Variants in multiple genes are associated with these disorders, with variable penetrance and inheritance. METHODS: We screened a large cohort (N = 1765) of patients with or at risk of CH using Sanger sequencing, selected according to phenotype, and conducted next-generation sequencing (NGS) in 51 families within our cohort. We report the clinical, hormonal, and neuroradiological phenotypes of patients with variants in known genes associated with CH. RESULTS: We identified variants in 178 patients: GH1/GHRHR (51 patients of 414 screened), PROP1 (17 of 253), POU1F1 (15 of 139), SOX2 (13 of 59), GLI2 (7 of 106), LHX3/LHX4 (8 of 110), HESX1 (8 of 724), SOX3 (9 of 354), OTX2 (5 of 59), SHH (2 of 64), and TCF7L1, KAL1, FGFR1, and FGF8 (2 of 585, respectively). NGS identified 26 novel variants in 35 patients (from 24 families). Magnetic resonance imaging showed prevalent hypothalamo-pituitary abnormalities, present in all patients with PROP1, GLI2, SOX3, HESX1, OTX2, LHX3, and LHX4 variants. Normal hypothalamo-pituitary anatomy was reported in 24 of 121, predominantly those with GH1, GHRHR, POU1F1, and SOX2 variants. CONCLUSION: We identified variants in 10% (178 of 1765) of our CH cohort. NGS has revolutionized variant identification, and careful phenotypic patient characterization has improved our understanding of CH. We have constructed a flow chart to guide genetic analysis in these patients, which will evolve upon novel gene discoveries.

Association of Homozygous PROP1 Mutation in a Saudi Family with Combined Pituitary Hormone Deficiency.

Background and Objectives: Combined pituitary hormone deficiency (CPHD) is a rare heterogeneous disease. It is characterized by the deficiency of growth hormone (GH) and shortage of at least one or more other hormones of the pituitary gland including thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin. Rare pathogenic variants in nearly 30 genes have been identified as an underlying cause of CPHD pathogenicity. Among these genes, paired-like homeobox 1 (PROP1) has been reported to be the most common cause of CPHD. Materials and Methods: In the present study, we investigated a large family of Saudi origin with three adult sisters suffering from short stature in combination of secondary amenorrhea. Results: Whole-exome sequencing followed by Sanger sequencing shows a homozygous missense variant (NM_006261.5; c.211C > T; p.R71C) in the PROP1 gene segregating with the disease phenotype within the family. In silico analysis studies show that this variant is highly conserved among several orthologues and is predicted as likely pathogenic using various bioinformatics tools. Conclusions: Our finding presents the first Saudi familial case of autosomal recessive form of CPHD caused by the PROP1 variant.

Copy number variation in pituitary stalk interruption syndrome: A large case series of sporadic non-syndromic patients and literature review.

Abnormal hypothalamic/posterior pituitary development appears to be a major determinant of pituitary stalk interruption syndrome (PSIS). The observation of familial cases and associated congenital abnormalities suggests a genetic basis. Single-gene mutations explain less than 5% of the cases, and whole exome sequencing has shown heterogeneous results. The present study aimed to assess copy number variation (CNV) using array-based comparative genomic hybridization (aCGH) in patients with non-syndromic PSIS and comprehensively review data from the literature on CNV analysis in congenital hypopituitarism (CH) patients. Twenty-one patients with sporadic CH from our outpatient clinics presented with ectopic posterior pituitary (EPP) and no central nervous system abnormalities on magnetic resonance image (MRI) or any other malformations on physical examination at presentation were enrolled in the study. aCGH using a whole-genome customized 400K oligonucleotide platform was performed in our patients. For the literature review, we searched for case reports of patients with CH and CNV detected by either karyotype or aCGH reported in PubMed up to November 2021. Thirty-five distinct rare CNVs were observed in 18 patients (86%) and two of them (6%) were classified as pathogenic: one deletion of 1.8 Mb in chromosome 17 (17q12) and one deletion of 15 Mb in chromosome 18 (18p11.32p11.21), each one in a distinct patient. In the literature review, 67 pathogenic CNVs were published in 83 patients with CH, including the present study. Most of these patients had EPP (78% out of the 45 evaluated by sellar MRI) and were syndromic (70%). The most frequently affected chromosomes were X, 18, 20 and 1. Our study has found that CNV can be a mechanism of genetic abnormality in non-syndromic patients with CH and EPP. In future studies, one or more genes in those CNVs, both pathogenic and variant of uncertain significance, may be considered as good candidate genes.

Heterozygous variants in SIX3 and POU1F1 cause pituitary hormone deficiency in mouse and man.

Congenital hypopituitarism is a genetically heterogeneous condition that is part of a spectrum disorder that can include holoprosencephaly. Heterozygous mutations in SIX3 cause variable holoprosencephaly in humans and mice. We identified two children with neonatal hypopituitarism and thin pituitary stalk who were doubly heterozygous for rare, likely deleterious variants in the transcription factors SIX3 and POU1F1. We used genetically engineered mice to understand the disease pathophysiology. Pou1f1 loss-of-function heterozygotes are unaffected; Six3 heterozygotes have pituitary gland dysmorphology and incompletely ossified palate; and the Six3+/-; Pou1f1+/dw double heterozygote mice have a pronounced phenotype, including pituitary growth through the palate. The interaction of Pou1f1 and Six3 in mice supports the possibility of digenic pituitary disease in children. Disruption of Six3 expression in the oral ectoderm completely ablated anterior pituitary development, and deletion of Six3 in the neural ectoderm blocked the development of the pituitary stalk and both anterior and posterior pituitary lobes. Six3 is required in both oral and neural ectodermal tissues for the activation of signaling pathways and transcription factors necessary for pituitary cell fate. These studies clarify the mechanism of SIX3 action in pituitary development and provide support for a digenic basis for hypopituitarism.

Growth hormone deficiency in a case of septo-optic-dysplasia due to SOX2 mutation: should we re-test patients during the transition period?

Gene mutations encoding transcription factors, including SOX2, have been associated with growth hormone deficiency (GHD) and abnormal pituitary development. Guidelines on GHD management in the transition period state that patients with genetic-based childhood-onset GHD can skip retesting due to a high likelihood of permanent GHD. We describe a case of septo-optic-dysplasia due to SOX2 mutation characterised by childhood-onset GHD, which showed a normal somatotropic function at the transition period. This case raises the opportunity to retest for GHD during the transition period, even in patients with a known genetic cause, in order to avoid inappropriate GH treatment.

POU1F1/Pou1f1 c.143-83A > G Variant Disrupts the Branch Site in Pre-mRNA and Leads to Dwarfism.

POU Class 1 Homeobox1 (POU1F1/Pou1f1) is a well-established pituitary-specific transcription factor, and causes, when mutated, combined pituitary hormone deficiency in humans and mice. POU1F1/Pou1f1 has 2 isoforms: the alpha and beta isoforms. Recently, pathogenic variants in the unique coding region of the beta isoform (beta domain) and the intron near the exon-intron boundary for the beta domain were reported, although their functional consequences remain obscure. In this study, we generated mice carrying the Pou1f1 c.143-83A>G substitution that recapitulates the human intronic variant near the exon-intron boundary for the beta domain. Homozygous mice showed postnatal growth failure, with an average body weight that was 35% of wild-type littermates at 12 weeks, which was accompanied by anterior pituitary hypoplasia and deficiency of circulating insulin-like growth factor 1 and thyroxine. The results of RNA-seq analysis of the pituitary gland were consistent with reduction of somatotrophs, and this was confirmed immunohistochemically. Reverse transcription polymerase chain reaction of pituitary Pou1f1 mRNA showed abnormal splicing in homozygous mice, with a decrease in the alpha isoform, an increase in the beta isoform, and the emergence of the exon-skipped transcript. We further characterized artificial variants in or near the beta domain, which were candidate positions of the branch site in pre-mRNA, using cultured cell-basis analysis and found that only c.143-83A>G produced transcripts similar to the mice model. Our report is the first to show that the c.143-83A>G variant leads to splicing disruption and causes morphological and functional abnormalities in the pituitary gland. Furthermore, our mice will contribute understanding the role of POU1F1/Pou1f1 transcripts in pituitary development.

Novel genes and variants associated with congenital pituitary hormone deficiency in the era of next-generation sequencing.

Combined pituitary hormone deficiency (CPHD) is not a rare disorder, with a frequency of approximately 1 case per 4,000 live births. However, in most cases, a genetic diagnosis is not available. Furthermore, the diagnosis is challenging because no clear correlation exists between the pituitary hormones affected and the gene(s) responsible for the disorder. Next-generation sequencing (NGS) has recently been widely used to identify novel genes that cause (or putatively cause) CPHD. This review outlines causative genes for CPHD that have been newly reported in recent years. Moreover, novel variants of known CPHD-related genes (POU1F1 and GH1 genes) that contribute to CPHD through unique mechanisms are also discussed in this review. From a clinical perspective, variants in some of the recently identified causative genes result in extra-pituitary phenotypes. Clinical research on the related symptoms and basic research on pituitary formation may help in inferring the causative gene(s) of CPHD. Future NGS analysis of a large number of CPHD cases may reveal new genes related to pituitary development. Clarifying the causative genes of CPHD may help to understand the process of pituitary development. We hope that future innovations will lead to the identification of genes responsible for CPHD and pituitary development.