LHX4 Mutations Research Articles

A patient with combined pituitary hormone deficiency and osteogenesis imperfecta associated with mutations in LHX4 and COL1A2

Genetic disorders have been shown to co-occur in individual patient. A Thai boy with features of osteogenesis imperfecta (OI) and combined pituitary hormone deficiency (CPHD) was identified. The causative mutations were investigated by whole exome and Sanger sequencing. Pathogenicity and pathomechanism of the variants were studied by luciferase assay. The proband was found to harbor a novel de novo heterozygous missense mutation, c.1531G > T (p.G511C), in COL1A2 leading to OI and a heterozygous missense variant, c.364C > T (p.R122W), in LHX4. The LHX4 p.R122W has never been reported to cause CPHD. The variant was predicted to be deleterious and found in the highly conserved LIM2 domain of LHX4. The luciferase assays revealed that the p.R122W was unable to activate POU1F1, GH1, and TSHB promoters, validating its pathogenic effect in CPHD. Moreover, the variant did not alter the function of wild-type LHX4, indicating its hypomorphic pathomechanism. In conclusion, the novel de novo heterozygous p.G511C mutation in COL1A2 and the heterozygous pathogenic p.R122W mutation in LHX4 were demonstrated in a patient with OI and CPHD. This study proposes that the mutations in two different genes should be sought in the patients with clinical features unable to be explained by a mutation in one gene.

LHX3 deficiency presenting in the United States with severe developmental delay in a child of Syrian refugee parents.

SummaryIn this case report, we present a novel mutation in Lim-homeodomain (LIM-HD) transcription factor, LHX3, manifesting as combined pituitary hormone deficiency (CPHD). This female patient was originally diagnosed in Egypt during infancy with Diamond Blackfan Anemia (DBA) requiring several blood transfusions. Around 10 months of age, she was diagnosed and treated for central hypothyroidism. It was not until she came to the United States around two-and-a-half years of age that she was diagnosed and treated for growth hormone deficiency. Her response to growth hormone replacement on linear growth and muscle tone were impressive. She still suffers from severe global development delay likely due to delay in treatment of congenital central hypothyroidism followed by poor access to reliable thyroid medications. Her diagnosis of DBA was not confirmed after genetic testing in the United States and her hemoglobin normalized with hormone replacement therapies. We will review the patient’s clinical course as well as a review of LHX3 mutations and the associated phenotype.Learning points:Describe an unusual presentation of undertreated pituitary hormone deficiencies in early lifeCombined pituitary hormone deficiency due to a novel mutation in pituitary transcription factor, LHX3Describe the clinical phenotype of combined pituitary hormone deficiency due to LHX3 mutations

Heterozygous LHX3 mutations may lead to a mild phenotype of combined pituitary hormone deficiency.

LHX3 is an LIM domain transcription factor involved in the early steps of pituitary ontogenesis. We report here functional studies of three allelic variants, including the first heterozygous variant of LHX3 NM_178138.5(LHX3):c.587T>C (p.(Leu196Pro)) that may be responsible for a milder phenotype of hypopituitarism. Our functional studies showed that NM_178138.5(LHX3):c.587T>C (p.(Leu196Pro)) was not able to activate target promoters in vitro, as it did not bind DNA, and likely affected LHX3 function via a mechanism of haplo-insufficiency. Our study demonstrates the possibility that patients with a heterozygous variant of LHX3 may have pituitary deficiencies, with a milder phenotype than patients with homozygous variants. It is thus of vital to propose an optimal follow-up of such patients, who, until now, were considered as not being at risk of presenting pituitary deficiency. The second variant NM_178138.5(LHX3):c.622C>G (p.(Arg208Gly)), present in a homozygous state, displayed decreased transactivating ability without loss of binding capacity in vitro, concordant with in silico analysis; it should thus be considered to affect LHX3 function. In contrast, the NM_178138.5(LHX3):c.929G>C (p.(Arg310Pro)) variant, in a heterozygous state, also predicted as deleterious in silico, proved functionally active in vitro, and should thus still be classified as a variant of unknown significance. Our study emphasizes the need for functional studies due to the limits of software-based predictions of new variants, and the possible association of a pituitary phenotype to heterozygous LHX3 variants.

Molecular analysis of brazilian patients with combined pituitary hormone deficiency and orthotopic posterior pituitary lobe reveals eight different PROP1 alterations with three novel mutations.

Mutations in PROP1, HESX1 and LHX3 are associated with combined pituitary hormone deficiency (CPHD) and orthotopic posterior pituitary lobe (OPP). To identify mutations in PROP1, HESX1 and LHX3 in a large cohort of patients with CPHD and OPP (35 Brazilian, two Argentinian). We studied 23 index patients with CPHD and OPP (six familial and 17 sporadic) as well as 14 relatives. PROP1 was sequenced by the Sanger method in all except one sporadic case studied using a candidate gene panel. Multiplex ligation-dependent probe amplification (MLPA) was applied to one familial case in whom PROP1 failed to amplify by PCR. In the 13 patients without PROP1 mutations, HESX1 and LHX3 were sequenced by the Sanger method. We identified PROP1 mutations in 10 index cases. Three mutations were novel: one affecting the initiation codon (c.1A>G) and two affecting splicing sites, c.109+1G>A and c.342+1G>C. The known mutations, c.150delA (p.Arg53Aspfs*112), c.218G>A (p.Arg73His), c.263T>C (p.Phe88Ser) and c.301_302delAG (p.Leu102Cysfs*8), were also detected. MLPA confirmed complete PROP1 deletion in one family. We did not identify HESX1 and LHX3 mutations by Sanger. PROP1 mutations are a prevalent cause of congenital CPHD with OPP, and therefore, PROP1 sequencing must be the first step of molecular investigation in patients with CPHD and OPP, especially in populations with a high frequency of PROP1 mutations. In the absence of mutations, massively parallel sequencing is a promising approach. The high prevalence and diversity of PROP1 mutations is associated with the ethnic background of this cohort.

Two novel LHX3 mutations in patients with combined pituitary hormone deficiency including cervical rigidity and sensorineural hearing loss

BackgroundCongenital combined pituitary hormone deficiency (CPHD) is a rare heterogeneous group of conditions. CPHD-type 3 (CPHD3; MIM# 221750) is caused by recessive mutations in LHX3, a LIM-homeodomain transcription factor gene. The isoforms of LHX3 are critical for pituitary gland formation and specification of the anterior pituitary hormone-secreting cell types. They also play distinct roles in the development of neuroendocrine and auditory systems.Case presentationHere, we summarize the clinical, endocrinological, radiological and molecular features of three patients from two unrelated families. Clinical evaluation revealed severe CPHD coupled with cervical vertebral malformations (rigid neck, scoliosis), mild developmental delay and moderate sensorineural hearing loss (SNHL). The patients were diagnosed with CPHD3 based on the array of hormone deficiencies and other associated syndromic symptoms, suggestive of targeted LHX3 gene sequencing. A novel missense mutation c.437G > T (p. Cys146Phe) and a novel nonsense mutation c.466C > T (p. Arg156Ter), both in homozygous forms, were found. The altered Cys146 resides in the LIM2 domain of the encoded protein and is a phylogenetically conserved residue, which mediates LHX3 transcription factor binding with a zinc cation. The p. Arg156Ter is predicted to result in a severely truncated protein, lacking the DNA binding homeodomain.ConclusionsConsidering genotype/phenotype correlation, we suggest that the presence of SNHL and limited neck rotation should be considered in the differential diagnosis of CPHD3 to facilitate molecular diagnosis. This report describes the first LHX3 mutations from Saudi patients and highlights the importance of combining molecular diagnosis with the clinical findings. In addition, it also expands the knowledge of LHX3-related CPHD3 phenotype and the allelic spectrum for this gene.

Contribution of LHX4 Mutations to Pituitary Deficits in a Cohort of 417 Unrelated Patients.

LHX4 encodes a LIM-homeodomain transcription factor that is implicated in early pituitary development. In humans, only 13 heterozygous LHX4 mutations have been associated with congenital hypopituitarism. The aims of this study were to evaluate the prevalence of LHX4 mutations in patients with hypopituitarism, to define the associated phenotypes, and to characterize the functional impact of the identified variants and the respective role of the 2 LIM domains of LHX4. We screened 417 unrelated patients with isolated growth hormone deficiency or combined pituitary hormone deficiency associated with ectopic posterior pituitary and/or sella turcica anomalies for LHX4 mutations (Sanger sequencing). In vitro studies were performed to assess the functional consequences of the identified variants. We identified 7 heterozygous variations, including p.(Tyr131*), p.(Arg48Thrfs*104), c.606+1G>T, p.Arg65Val, p.Thr163Pro, p.Arg221Gln, and p.Arg235Gln), that were associated with variable expressivity; 5 of the 7 were also associated with incomplete penetrance. The p.(Tyr131*), p.(Arg48Thrfs*104), p.Ala65Val, p.Thr163Pro, and p.Arg221Gln LHX4 variants are unable to transactivate the POU1F1 and GH promoters. As suggested by transactivation, subcellular localization, and protein-protein interaction studies, p.Arg235Gln is probably a rare polymorphism. Coimmunoprecipitation studies identified LHX3 as a potential protein partner of LHX4. As revealed by functional studies of LIM-defective recombinant LHX4 proteins, the LIM1 and LIM2 domains are not redundant. This study, performed in the largest cohort of patients screened so far for LHX4 mutations, describes 6 disease-causing mutations that are responsible for congenital hypopituitarism. LHX4 mutations were found to be associated with variable expressivity, and most of them with incomplete penetrance; their contribution to pituitary deficits that are associated with an ectopic posterior pituitary and/or a sella turcica defect is ∼1.4% in the 417 probands tested.

Whole-exome sequencing identifies homozygous GPR161 mutation in a family with pituitary stalk interruption syndrome.

Pituitary stalk interruption syndrome (PSIS) is a rare, congenital anomaly of the pituitary gland characterized by pituitary gland insufficiency, thin or discontinuous pituitary stalk, anterior pituitary hypoplasia, and ectopic positioning of the posterior pituitary gland (neurohypophysis). The clinical presentation of patients with PSIS varies from isolated growth hormone (GH) deficiency to combined pituitary insufficiency and accompanying extrapituitary findings. Mutations in HESX1, LHX4, OTX2, SOX3, and PROKR2 have been associated with PSIS in less than 5% of cases; thus, the underlying genetic etiology for the vast majority of cases remains to be determined. We applied whole-exome sequencing (WES) to a consanguineous family with two affected siblings who have pituitary gland insufficiency and radiographic findings of hypoplastic (thin) pituitary gland, empty sella, ectopic neurohypophysis, and interrupted pitiutary stalk-characteristic clinical diagnostic findings of PSIS. WES was applied to two affected and one unaffected siblings. WES of two affected and one unaffected sibling revealed a unique homozygous missense mutation in GPR161, which encodes the orphan G protein-coupled receptor 161, a protein responsible for transducing extracellular signals across the plasma membrane into the cell. Mutations of GPR161 may be implicated as a potential novel cause of PSIS.

Lhx3 is required to maintain cancer cell development of high-grade oligodendroglioma

The LHX genes play a substantial role in an amount of adorning processes. Potential roles of LHXs have been accepted and approved in an assortment of neoplastic tissues as bump suppressors or promoters depending on bump cachet and types. The aim of this abstraction was to investigate the action role of LHXs in the animal High-grade Oligodendroglioma (HG-OT). The gene announcement changes of LHXs in HG-OT tissues compared with non-cancerous colorectal tissues were detected using application real-time quantitative about-face transcriptase-polymerase alternation acknowledgment (QRT-PCR) assay and immunohistochemistry. And we articulate the gene LHX3 that was decidedly up-regulated in HG-OT by QRT-PCR assay and immunohistochemistry. Furthermore, it was obvious that LHX3 responds to blight corpuscle admeasurement in vitro and LHX3 announcement activated with animated β-catenin levels in HG-OT and β-catenin action was appropriate for LHX3's oncogenic effects. Mechanistically, LHX3 facilitates TCF4 to bind to β-catenin and facilitates LHX3/TCF4/β-catenin circuitous and trans-active it's after ambition gene. LHX3 mutations that agitate the LHX3-β-catenin alternation partially anticipate its action in bump cells. All in all, LHX3 is a frequently activated bump apostle that actuates Wnt/β-catenin signaling in blight beef of HG-OT.

PO-0081 Pituitary Stalk Interruption Syndrome: Clinical, Radiologic And Therapeutic Particularity

Background Patients with congenital hypopituitarism might have the classic triad of pituitary stalk interruption syndrome (PSIS), which consists of: an interrupted or thin pituitarys talk, an absent or ectopic posterior pituitary (EPP), and anterior pituitary hypoplasia or aplasia. The most remarkable clinical manifestations of patients with PSIS was growth retardation. Objective To analyse the clinical, auxological and radiologic characteristics of the patients with PSIS to achieve better comprehension of this pathology. Methods Data of patients with PSIS were retrospectively analysed for the clinical, laboratory and imaging features. Results Five patients were included (4 girls and 1 boy). They are aged at the first clinical manifestation from 1 month to 3 years. The symptoms that led to the diagnosis were failure to thrive in four cases and polyuria-polydipsia syndrome in one case. A complete growth hormone deficiency was confirmed in four cases, one was complicated with central hypothyroidism and one was accompanied by central adrenocortical hypofunction. The last patient present only central diabetes insipidus. Hypothalamo-pituitary MRI was performed in all of the patients showed one or more elements of the classic triad. A causative mutation was studied in two patients. None HESX1 or LHX4 mutations was found. Conclusion The PSIS is relatively frequent. The outcome is progressive evolution towards panhypopituitarism. The treatment consists in hormone replacement therapy.

Oncogenicity of LHX4 in colorectal cancer through Wnt/β-catenin/TCF4 cascade.

The LHX genes play an important role in a number of developmental processes. Potential roles of LHXs have been demonstrated in various neoplastic tissues as tumor suppressors or promoters depending on tumor status and types. The aim of this study was to investigate the function role of LHXs in the human colorectal cancer (CRC). The gene expression changes of LHXs in CRC tissues compared with noncancerous colorectal tissues was detected using real-time quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) analysis and immunohositochemistry. And we identified the gene LHX4 that were significantly upregulated in CRC by QRT-PCR analysis and immunohistochemistry. Furthermore, we discovered that LHX4 promoted cancer cell proliferation in vitro, and LHX4 expression correlated with elevated β-catenin levels in CRC and β-catenin function was required for LHX4's oncogenic effects. Mechanistically, LHX4 facilitate TCF4 to bind to β-catenin and form a stable LHX4/TCF4/β-catenin complex and transactive its downstream target gene. LHX4 mutations that disrupt the LHX4-β-catenin interaction partially prevent its function in tumor cells. All in all, LHX4 is a commonly activated tumor promoter that activate Wnt/β-catenin signaling in cancer cells of CRC.

Molecular and Clinical Findings in Patients with LHX4 and OTX2 Mutations.

The pituitary gland produces hormones that play important roles in both the development and homeostasis of the body. Ontogeny of the anterior and posterior pituitary is orchestrated by inputs from neighboring tissues, cellular signaling molecules and transcription factors. Disruption of expression or function of these factors has been implicated in the etiology of combined pituitary hormone deficiency (CPHD). These include the transcription factors HESX1, PROP1, POU1F1, LHX3, LHX4, OTX2, SOX2, SOX3 and GLI2. This review focuses on summarizing most recent mutations in LHX4 and OTX2 responsible for pituitary hormone deficiency. In both genetic defects of LHX4 and OTX2, there is high variability in clinical manifestations even in the same family. In addition, there is no clear phenotype-genotype correlation. These findings indicate that the other genetic and/or environmental factors influence the phenotype. In addition, the variability might reflect a plasticity during pituitary development and maintenance. Over the past two decades, a genetic basis for pituitary hormone deficiency and the mechanism of pituitary development have been clarified. It should be kept in mind that this review is not comprehensive, and defects of other transcriptional factors have been described in patients with CPHD. Furthermore, the causes in many patients with CPHD have not yet been determined. Therefore, continuing efforts for the clarification of the etiology are necessary.

Molecular and Clinical Findings in Patients with <i>LHX4</i> and <i>OTX2</i> Mutations

The pituitary gland produces hormones that play important roles in both the development and homeostasis of the body. Ontogeny of the anterior and posterior pituitary is orchestrated by inputs from neighboring tissues, cellular signaling molecules and transcription factors. Disruption of expression or function of these factors has been implicated in the etiology of combined pituitary hormone deficiency (CPHD). These include the transcription factors HESX1, PROP1, POU1F1, LHX3, LHX4, OTX2, SOX2, SOX3 and GLI2. This review focuses on summarizing most recent mutations in LHX4 and OTX2 responsible for pituitary hormone deficiency. In both genetic defects of LHX4 and OTX2, there is high variability in clinical manifestations even in the same family. In addition, there is no clear phenotype-genotype correlation. These findings indicate that the other genetic and/or environmental factors influence the phenotype. In addition, the variability might reflect a plasticity during pituitary development and maintenance. Over the past two decades, a genetic basis for pituitary hormone deficiency and the mechanism of pituitary development have been clarified. It should be kept in mind that this review is not comprehensive, and defects of other transcriptional factors have been described in patients with CPHD. Furthermore, the causes in many patients with CPHD have not yet been determined. Therefore, continuing efforts for the clarification of the etiology are necessary.

Gradual Loss of ACTH Due to a Novel Mutation in LHX4: Comprehensive Mutation Screening in Japanese Patients with Congenital Hypopituitarism

Mutations in transcription factors genes, which are well regulated spatially and temporally in the pituitary gland, result in congenital hypopituitarism (CH) in humans. The prevalence of CH attributable to transcription factor mutations appears to be rare and varies among populations.This study aimed to define the prevalence of CH in terms of nine CH-associated genes among Japanese patients. We enrolled 91 Japanese CH patients for DNA sequencing of POU1F1, PROP1, HESX1, LHX3, LHX4, SOX2, SOX3, OTX2, and GLI2. Additionally, gene copy numbers for POU1F1, PROP1, HESX1, LHX3, and LHX4 were examined by multiplex ligation-dependent probe amplification. The gene regulatory properties of mutant LHX4 proteins were characterized in vitro. We identified two novel heterozygous LHX4 mutations, namely c.249-1G>A, p.V75I, and one common POU1F1 mutation, p.R271W. The patient harboring the c.249-1G>A mutation exhibited isolated growth hormone deficiency at diagnosis and a gradual loss of ACTH, whereas the patient with the p.V75I mutation exhibited multiple pituitary hormone deficiency. In vitro experiments showed that both LHX4 mutations were associated with an impairment of the transactivation capacities of POU1F1 andαGSU, without any dominant-negative effects. The total mutation prevalence in Japanese CH patients was 3.3%. This study is the first to describe, a gradual loss of ACTH in a patient carrying an LHX4 mutation. Careful monitoring of hypothalamic–pituitary -adrenal function is recommended for CH patients with LHX4 mutations.

Unilateral agenesis of internal carotid artery associated with congenital combined pituitary hormone deficiency and pituitary stalk interruption without HESX1, LHX4 or OTX2 mutation: a case report

Agenesis of internal carotid artery (ICA) is an unusual finding in subjects with congenital Combined Pituitary hormone deficiency (CPHD) with only nine cases being reported to date but to our best knowledge none of them was genetically investigated. A 10-years old girl presented with severe growth failure (height 103 cm) with substantial bone age delay (3 years). She had no history of perinatal insults or familial CPHD. There was no evidence of mental retardation or craniofacial dysmorphism or ophtalmological abnormalities. She was first diagnosed with GH and TSH deficiency. Cerebral magnetic resonance imaging (MRI) showed hypoplastic anterior pituitary, flat sella turcica, absent pituitary stalk with ectopic posterior pituitary as well as agenesis of the left ICA and the left carotid canal. Genomic analysis of pituitary transcription factor HESX1, LHX4 and OTX2 showed no mutations. Treatment with GH and thyroxine was started. The patient remained free of neurovascular symptoms for 5 years but she presented at the age of 15 years with delayed puberty related to an evolving gonadotropin deficiency. ICA agenesis associated with CPHD is unusual and is often asymptomatic in children. Since the CPHD with pituitary stalk interruption cannot be due to HESX1, LHX4 or OTX2 mutation in our case, other pathogenetic mechanisms may be responsible for CPHD associated with unilateral ICA agenesis.

Symptomatic Heterozygotes and Prenatal Diagnoses in a Nonconsanguineous Family with Syndromic Combined Pituitary Hormone Deficiency Resulting from Two NovelLHX3Mutations

Only 11 mutations have been reported in the transcription factor LHX3, known to be important for the development of the pituitary and motor neurons. All patients were homozygous, with various syndromic forms of combined pituitary hormone deficiency (CPHD), hampering to allocate, in these consanguineous patients, the respective contribution of LHX3 and additional genes to each symptom. The aim of the study was to report the family history and the molecular basis of a nonconsanguineous patient with syndromic CPHD. The patient, who presented at birth with respiratory distress, had a syndromic CPHD, including severe scoliosis, and normal intelligence. His father and paternal grandmother displayed limited head rotation. Two new LHX3 defects were identified. The paternally inherited c.252-3C>G mutation, which disrupts an acceptor splice site, would lead to severely truncated proteins containing a single LIM domain, resembling LIM-only proteins. Coexpression studies revealed the dominant-negative effect of this LIM-only protein over the wild-type LHX3. The maternally inherited p.Cys118Tyr mutation results in partial loss of transcriptional activity and synergy with POU1F1. Given the severity of the patient's phenotype, two prenatal diagnoses were performed: the first led to pregnancy interruption, the second to the birth of a healthy boy. This study of the first nonconsanguineous patient with LHX3 mutations demonstrates the pleiotropic roles of LHX3 during development and its full involvement in the complex disease phenotype. Isolated limitation of head rotation may exist in heterozygous carriers and would result from a dominant-negative effect. These data allowed the first prenatal diagnoses of this severe condition to be performed.

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.

A novel mutation of LHX3 is associated with combined pituitary hormone deficiency including ACTH deficiency, sensorineural hearing loss, and short neck—a case report and review of the literature

The LHX3 LIM-homeodomain transcription factor gene is required for normal pituitary and motoneuron development. LHX3 mutations are associated with growth hormone, prolactin, gonadotropin, and TSH deficiency; abnormal pituitary morphology; and may be accompanied with limited neck rotation and sensorineural hearing loss. We report on a boy, who presented with hypoglycemia in the newborn period. He is the second child of healthy unrelated parents. Short neck, growth hormone deficiency, and central hypothyroidism were diagnosed at a general pediatric hospital. Growth hormone and levothyroxine treatment were started, and blood sugar normalized with this treatment. On cerebral MRI, the anterior pituitary gland was hypoplastic. Sensorineural hearing loss was diagnosed by auditory testing. During follow-up, six repeatedly low morning cortisol levels (<1μg/dl) and low ACTH levels (<10pg/ml) were documented, so ACTH deficiency had developed over time and therefore hydrocortisone replacement was started at 1.5years of age. Mutation analysis of the LHX3 gene revealed a homozygous stop mutation in exon 2: c.229C>T (CGA > TGA), Arg77stop (R77X). A complete loss of function is assumed with this homozygous stop mutation. We report a novel LHX3 mutation, which is associated with combined pituitary hormone deficiency including ACTH deficiency, short neck, and sensorineural hearing loss. All patients with LHX3 defects should undergo longitudinal screening for ACTH deficiency, since corticotrope function may decline over time. All patients should have auditory testing to allow for regular speech development.

PROP1, HESX1, POU1F1, LHX3 and LHX4 Mutation and Deletion Screening and GH1 P89L and IVS3+1/+2 Mutation Screening in a Dutch Nationwide Cohort of Patients with Combined Pituitary Hormone Deficiency

Background/Aims: Mutation frequencies of genes involved in combined pituitary hormone deficiency (CPHD) vary substantially between populations. The HYPOPIT study aims to obtain an overall picture of known and new genetic defects and variations in a nationwide cohort of Dutch (mostly) sporadic CPHD patients. Methods: We screened 79 CPHD patients from 78 families (regardless of MRI and hormonal phenotype) for mutations and deletions in PROP1, HESX1, POU1F1, LHX3 and LHX4, as well as the P89L and IVS3+1/+2 mutations in GH1, recently described to cause pituitary hormone impairment in addition to GH deficiency. Results: We did not find any mutation or deletion in PROP1, HESX1, LHX3 or LHX4, nor GH1 P89L and GH1 IVS3+1/+2 mutations. Among 12 patients with a typical ‘POU1F1 phenotype’, 1 patient was formerly known to have a POU1F1 mutation. This results in a POU1F1 mutation frequency in these patients of 8.3%. Conclusion: Thorough screening for mutations and deletions in PROP1, HESX1, POU1F1, LHX3, LHX4, as well as screening for GH1 P89L or GH1 IVS3+1/+2 mutations, did not reveal any genetic defect in our cohort of CPHD patients except for one formerly known POU1F1 mutation in 1 patient. Future research should focus on alternative explanations for CPHD, like other genes or environmental factors.

A coding SNP of LHX4 gene is associated with body weight and body length in bovine

Heterozygous mutations in LHX4 are associated with combined pituitary hormone deficiency. In this study, the polymorphism of LHX4-HaeIII locus was revealed in 822 individuals from four Chinese cattle breeds. The PCR-RFLP analysis showed that there were three genotypes: GG, GA, AA. The frequencies of genotype GG ranged from 0.6620 to 0.9789 in analyzed populations. The genotypic frequencies of LHX4 locus in the four populations all agreed with Hardy-Weinberg equilibrium (P > 0.05). Distributions of genotypic frequencies of different breeds (QC, NY, JX, CH) at this locus were found to be significantly different based on a chi(2) test (P < 0.001). The genetic diversity analysis revealed the JX cattle possessed intermediate genetic diversity, and the other three Chinese cattle breeds belonged to poor genetic diversity. Correlation analysis with growth traits in the NY breed indicated that: the animals with genotype GA had greater body weight than those with genotype GG (P < 0.05); the animals with GA genotype owned significantly longer body length than the ones with GG genotype (P < 0.05) at 18 and 24 months.

Congenital pituitary hormone deficiencies: role of LHX3/LHX4 genes

LHX3 and LHX4 are LIM domain transcription factors involved in the early steps of pituitary organogenesis. They are necessary for the proper differentiation of Rathke’s pouch that gives rise to the anterior pituitary lobe. Mutations of these transcription factors are involved in congenital hypopituitarism: to date, nine mutations of LHX3 have been reported, responsible for variable pituitary hormone deficiencies and extrapituitary manifestations, including limited neck rotation. By contrast, only five LHX4 mutations have been reported, responsible for variable hormone deficiencies, and pituitary/intracranial abnormalities. Future investigations will aim to better understand human pituitary organogenesis and to shed light on the interspecies differences in the roles of these transcription factors.