Pituitary Transcription Factor Genes Research Articles

RF17 | PMON23 Argentinian multicentric genetic study of pituitary hormonal deficiencies using a custom panel based on single molecule molecular inversion probes

Abstract Hypopituitarism with deficiency of one or more pituitary hormones (combined pituitary hormone deficiency or CPHD) can vary in severity and age at presentation. Additionally, the hormone abnormalities may evolve with time necessitating frequent evaluation. These hormonal deficits can also be present as part of a syndrome, with patients showing extrapituitary abnormalities such as eye or forebrain malformations. Over the past decade, there has been an explosion in the knowledge of the genetic cascade that orchestrates hypothalamic and pituitary development. Several transcription factors and signaling molecules are critical for cell differentiation and proliferation at a very early stage of gestation. However, more genes remain to be identified in order to provide patients with a definitive aetiology. We studied 95 children with congenital hypopituitarism from seven pediatric hospitals from Argentina. Children with non-endocrine, non-familial idiopathic short stature served as a control group (n=100). A custom exon capture panel based on single-molecule molecular inversion probes sequencing (MIPS) was performed in probands and parents. This panel tests 104 genes: including a selection of reported and candidate genes chosen from our knowledge of pituitary development in mice and PROP1 interacting proteins. We found at least 1 variant in 50 probands. The prevalence of known variants in the pituitary transcription factor genes PROP1 and PIT1 (frequently mutated in CPHD) was low in our cohort. A significant number of disease-causing variants were found in LHX3, LHX4, GLI2 and OTX2. An important advance of our study is the identification of pathogenic variants in recently discovered and novel genes. We found an heterozygous variant in the Roundabout (ROBO) receptor homolog 1 gene: ROBO1;p.Arg1504* in a patient with CPHD and septo-optic dysplasia (SOD); two variants in Steroid Receptor SRA1: p. Ile179Thr and p.Val110delinsArgLeu in a patient with CPHD and hypogonadism hypogonadotropic and a missense variant in Semaphorin 3A SEMA3A: p.Val588Leu in a case of CPHD and aortic coarctation. Our findings support evidence that the etiology of congenital hypopituitarism is highly heterogeneous and may be infrequently monogenic with full penetrance, underlying a more complex pathogenesis. Presentation: Sunday, June 12, 2022 12:36 p.m. - 12:41 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Genetic analysis of adult Slovenian patients with combined pituitary hormone deficiency.

Among genetic causes of combined pituitary hormone deficiency (CPHD), mutations of genes coding for transcription factors involved in pituitary development have been implicated. Congenital CPHD is a rare disease; therefore, it is important to expand the knowledge about incidence and regional distribution of specific mutations. The aim of this paper is to report results of genetic analyses of adult Slovenian patients with CPHD. Twenty-three adult Slovenian patients with early childhood onset CPHD were included in the study. Blood samples were collected through the GENHYPOPIT network to assess possible mutations of six genes (PROP1/HESX1/LHX4/LHX3/POU1F1) involved in the pituitary development following an established algorithm. In seven out of 23 patients (30%) a specific mutation in genes encoding pituitary transcription factors was discovered. In five patients, two different mutations of the PROP1 gene (c.150delA and c.301-302delAG) were identified. One patient was heterozygous for a missense variant in the LHX4 gene. Additionally, one patient was positive for a mutation in the gene coding for prokineticin receptor-2. Our study confirms that the two most common mutations of the PROP1 gene globally are also the most frequent mutations in the cohort of adult Slovenian patients with CHPD. Other mutations of pituitary transcription factor genes are extremely rare.

Genetic factors in hypopituitarism. The role of transcription factors in pituitary hormone deficiency

Developmental disorders affecting the hypothalamic-pituitary system can result in pituitary hormone deficiency showing a diverse clinical presentation. A significant majority of these disorders are closely linked to defects in transcription factor genes which play a major role in pituitary development. Those affecting the early phase of organogenesis typically lead to complex conditions affecting the pituitary as well as structures in the central nervous system. Transcription factors involved in the late phase can result in combined but rarely isolated pituitary hormone deficiency without extra-pituitary manifestation. Identifying the defects in these pituitary transcription factor genes may provide a useful tool in predicting disease progression as well as screening family members. Several pituitary transcription factors can be detected in the adult gland as well which is strongly emphasized in the World Health Organization's most recent guideline for pituitary tumor classification. Our review summarizes the current essential knowledge relevant for clinical endocrinologists. Orv Hetil. 2018; 159(7): 278-284.

Rare Frequency of Mutations in Pituitary Transcription Factor Genes in Combined Pituitary Hormone or Isolated Growth Hormone Deficiencies in Korea.

PurposeCongenital hypopituitarism is caused by mutations in pituitary transcription factors involved in the development of the hypothalamic-pituitary axis. Mutation frequencies of genes involved in congenital hypopituitarism are extremely low and vary substantially between ethnicities. This study was undertaken to compare the clinical, endocrinological, and radiological features of patients with an isolated growth hormone deficiency (IGHD) or combined pituitary hormone deficiency (CPHD).Materials and MethodsThis study included 27 patients with sporadic IGHD and CPHD. A mutation analysis of the POU1F1, PROP1, LHX3, LHX4, and HESX1 genes was performed using genomic DNA from peripheral blood leukocytes.ResultsIGHD and CPHD were observed in 4 and 23 patients, respectively. Mean age at diagnosis was 8.28±7.25 years for IGHD and 13.48±10.46 years for CPHD (p=0.37). Serum insulin-like growth factor-1 and peak growth hormone (GH) levels following GH stimulation tests were significantly lower in patients with CPHD than in those with IGHD (p<0.05). Sellar MRI findings revealed structural abnormalities in 3 patients with IGHD (75%) and 21 patients with CPHD (91.3%) (p=0.62). A mutation analysis identified homozygous p.R109Q mutations in HESX1 in a patient with CPHD. Patients with CPHD had more severe GHD than those with IGHD.ConclusionThe frequency of defects in the genes encoding pituitary transcription factors was extremely low in Korean patients with congenital hypopituitarism. Environmental factors and the impact of other causative genes may contribute to this clinical phenotype.

PROP1 triggers epithelial-mesenchymal transition-like process in pituitary stem cells.

Mutations in PROP1 are the most common cause of hypopituitarism in humans; therefore, unraveling its mechanism of action is highly relevant from a therapeutic perspective. Our current understanding of the role of PROP1 in the pituitary gland is limited to the repression and activation of the pituitary transcription factor genes Hesx1 and Pou1f1, respectively. To elucidate the comprehensive PROP1-dependent gene regulatory network, we conducted genome-wide analysis of PROP1 DNA binding and effects on gene expression in mutant mice, mouse isolated stem cells and engineered mouse cell lines. We determined that PROP1 is essential for stimulating stem cells to undergo an epithelial to mesenchymal transition-like process necessary for cell migration and differentiation. Genomic profiling reveals that PROP1 binds to genes expressed in epithelial cells like Claudin 23, and to EMT inducer genes like Zeb2, Notch2 and Gli2. Zeb2 activation appears to be a key step in the EMT process. Our findings identify PROP1 as a central transcriptional component of pituitary stem cell differentiation.

Genetic background of inherited multiple pituitary hormone deficiency. Mutations ofPROP1gene in Hungary

In this work I analysed the outcome of growth hormone replacement treatment in patients with inherited form of multiple pituitary hormone deficiency and examined diseased-causing mutations of pituitary transcription factor genes which may underlie this disorder. The results showed that after treatment for a longer than 7-year period with a growth hormone preparation available under well-controlled distribution, the mean height of children with growth hormone deficiency reached the normal national reference range adjusted for age and sex. After establishment of clinical criteria for screening PROP1 gene mutations, I performed mutational analysis of all coding exons of this gene in 35 patients with inherited form of multiple pituitary hormone deficiency. With these studies, diseases-causing PROP1 gene mutations were detected in 15 of the 35 patients (43%). It was also found that more than 80% of mutant alleles were accounted for by those containing the 150delA and 301-302delGA mutations of the PROP1 gene. Importantly, these findings indicated a high relevance of mutational "hot spots" of the PROP1 gene in Hungarian patients with inherited form of multiple pituitary hormone deficiency and they also offered an opportunity for the development of rational and cost-effective screening strategy. When clinical and hormonal findings of patients with and without PROP1 gene mutations were compared, results showed that growth hormone deficiency was diagnosed at earlier age of life in patients with PROP1 gene mutations, but the severity of growth retardation at the time of diagnosis of growth hormone deficiency or the age of patients at the time of manifestation of other pituitary hormone deficiencies (TSH, LH, FSH and ACTH) were similar in the two groups of patients. In 15 patients inherited form of multiple pituitary hormone deficiency who had no PROP1 gene mutations, exon 6 of the POU1F1 gene containing a mutational "hot spot" was also examined but no mutations were found. Thus, these results do not support a significant role of the mutational "hot spot" of the POU1F1 gene in Hungarian patients with inherited form of multiple pituitary hormone deficiency. Finally, I introduced a method for the detection of mutations of the PITX2 gene, a pituitary transcription factor that plays a role not only in pituitary development and differentiation but also in the lateralization of organs. With the use of this method, I performed mutational analysis of all coding exons of this gene in an exceptionally unique patient who had both situs inversus totalis and inherited form of multiple pituitary hormone deficiency, but no mutation was found. Thus, the findings in this patient failed to indicate that mutation of the PITX2 gene is involved in the pathomechanism of situs inversus totalis associated with inherited form of multiple pituitary hormone deficiency.

Pituitary stalk interruption syndrome in 83 patients: novel HESX1 mutation and severe hormonal prognosis in malformative forms

Pituitary stalk interruption syndrome (PSIS) is a particular entity in the population of patients with hypopituitarism. Only rare cases have a known genetic cause. i) To compare subgroups with or without extra-pituitary malformations (EPM) in a cohort of PSIS patients to identify predictive factors of evolution, ii) to determine the incidence of mutations of the known pituitary transcription factor genes in PSIS. Study design We analyzed features of 83 PSIS patients from 80 pedigrees and screened HESX1, LHX4, OTX2, and SOX3 genes. PSIS had a male predominance and was rarely familial (5%). Pituitary hypoplasia was observed only in the group with EPM. Multiple hormone deficits were observed significantly more often with versus without EPM (87.5 vs 69.5% respectively). Posterior pituitary location along the stalk was a significant protective factor regarding severity of hormonal phenotype. A novel HESX1 causative mutation was found in a consanguineous family, and two LHX4 mutations were present in familial PSIS. PSIS patients with EPM had a more severe hormonal disorder and pituitary imaging status, suggesting an antenatal origin. HESX1 or LHX4 mutations accounted for <5% of cases and were found in consanguineous or familial cases.

Mutation and Gene Copy Number Analyses of Six Pituitary Transcription Factor Genes in 71 Patients with Combined Pituitary Hormone Deficiency: Identification of a Single Patient withLHX4Deletion

Mutations of multiple transcription factor genes involved in pituitary development have been identified in a minor portion of patients with combined pituitary hormone deficiency (CPHD). However, copy number aberrations involving such genes have been poorly investigated in patients with CPHD. We aimed to report the results of mutation and gene copy number analyses in patients with CPHD. Seventy-one Japanese patients with CPHD were examined for mutations and gene copy number aberrations affecting POU1F1, PROP1, HESX1, LHX3, LHX4, and SOX3 by PCR-direct sequencing and multiplex ligation-dependent probe amplification. When a deletion was indicated, it was further studied by fluorescence in situ hybridization, oligoarray comparative genomic hybridization, and serial sequencing for long PCR products encompassing the deletion junction. We identified a de novo heterozygous 522,009-bp deletion involving LHX4 in a patient with CPHD (GH, TSH, PRL, LH, and FSH deficiencies), anterior pituitary hypoplasia, ectopic posterior pituitary, and underdeveloped sella turcica. We also identified five novel heterozygous missense substitutions (p.V201I and p.H387P in LHX4, p.T63M and p.A322T in LHX3, and p.V53L in SOX3) that were assessed as rare variants by sequencing analyses for control subjects and available parents and by functional studies and in silico analyses. The results imply the rarity of abnormalities affecting the six genes in patients with CPHD and the significance of the gene copy number analysis in such patients.

The natural history of the R120C PROP1 mutation reveals a wide phenotypic variability in two untreated adult brothers with combined pituitary hormone deficiency

Combined pituitary hormone deficiency (CPHD) corresponds to impaired production of growth hormone (GH) and other anterior pituitary hormones. The genetic form of CPHD may result from mutations in pituitary transcription factor genes, and PROP1 is the most commonly mutated gene in these cases. Patients with PROP1 mutations may have variable CPHD phenotypes but, because they are usually treated in childhood, the wide phenotypic variability caused by these mutations may not be thoroughly appreciated. Clinical follow-up and molecular analysis of PROP1 in two adult brothers with CPHD, born from consanguineous parents, and not treated until late adulthood. The homozygous R120C mutation was identified in the brothers. Their clinical follow-up showed a wide phenotypic variability: hypogonadism was severe and prevented pubertal development in both, but their final heights were remarkably different, pointing to different degrees in severity of GH/TSH deficiencies; cortisol deficiency developed late in both, but at least 10 yr apart. The lack of treatment in childhood and adolescence allowed the appreciation of the entire natural history of the CPHD caused by the R120C mutation, and it revealed a remarkable phenotypic variability even in siblings with a very similar genetic background.

Genetic characterization of growth hormone deficiency and resistance: implications for treatment with recombinant growth hormone.

Growth failure can be caused by deficient growth hormone production or action. The genes involved in pituitary development, somatotrope function, as well as growth hormone synthesis, secretion, and action have recently been characterized in considerable detail. Familial growth failure has played an important role in identifying these genes, and a large number of mutations adversely affecting the development and function of the growth hormone/insulin-like growth factor axis have been discovered. Inactivating mutations leading to growth retardation in humans have been identified in several pituitary transcription factor genes (HESX1, PITX2, LHX3, PROP1, POU1F1) as well as in genes encoding the growth hormone-releasing hormone receptor (GHRH-R), the G(s) protein alpha subunit (GNAS1), growth hormone itself (GH-1), the growth hormone receptor (GHR), and in a single case each, the insulin-like growth factor I (IGF-I) and the IGF-I receptor. Mutations in pituitary transcription factors cause developmental abnormalities of the pituitary and deficiency of multiple pituitary hormones [growth hormone (GH), prolactin (Prl), thyrotropin (TSH) and lutropin/follitropin (LH/FSH)]. Most of the syndromes respond well to therapy with recombinant GH; exceptions are antibody-mediated resistance in GHD type IA (not all patients) and cases of Laron syndrome (GHR deficiency). Such patients respond to IGF-I therapy. This review summarizes the molecular genetics, functional defects, phenotypes, diagnostic considerations and therapeutic aspects of syndromes associated with mutations in the relevant genes.