Mutation analysis of POUF-1, PROP-1 and HESX-1 show low frequency of mutations in children with sporadic forms of combined pituitary hormone deficiency and septo-optic dysplasia

Comparison of clinical characteristics of a pediatric cohort with combined pituitary hormone deficiency caused by mutation of the PROP1 gene or of other origins

The most commonly identified genetic cause of combined pituitary hormone deficiency (CPHD) is PROP1 gene mutations. The aim of the study was to compare selected clinical features of patients with CPHD caused by variants of the PROP1 gene (CPHD-PROP1) and patients with inborn CPHD of other etiology (CPHD-nonPROP1).

MATERIAL AND METHODS

The retrospective analysis included childhood medical records of 74 patients (32 female) with CPHD, including 43 patients (23 female) with the mutation in the PROP1 gene.

RESULTS

Patients with CPHD-PROP1 compared to the CPHD-nonPROP1 presented with the following: significantly higher median birth weight (0.21 vs. - 0.29 SDS, p = 0.019), lower growth velocity within 3 years preceding growth hormone administration (- 2.7 vs. - 0.8 SDS, p < 0.001), higher mean maximal blood concentration of growth hormone within the stimulation process (1.2 vs. 1.08 ng/mL, p = 0.003), lower TSH (1.8 vs. 2.4 µIU/mL, p < 0.001), significantly lower prolactin concentrations (128 vs. 416.3 µIU/mL, p < 0.001), and less frequent typical signs of hypogonadism at birth in boys (n = 6; 30% vs. n = 12, 54%, p < 0.001). Secondary adrenal insufficiency was less frequent in CPHD-PROP1 (20 vs. 25 cases, p = 0.006) and occurred at a later age (13.4 vs. 10.4 years). MRI of the pituitary gland in CPHD-PROP1 revealed a small pituitary gland (21 cases), pituitary gland enlargement (eight cases), and one pituitary stalk interruption and posterior lobe ectopy, while it was normal in nine cases.

CONCLUSION

Patients with the PROP1 mutations present a clinical picture significantly different from that of other forms of congenital hypopituitarism. Certain specific clinical results may lead to the successful identification of children requiring diagnostics for the PROP1 gene mutation.

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.

Delineating septo-optic dysplasia

BACKGROUND

Septo-optic dysplasia (SOD), once a variable triad of septum pellucidum defects (SPDs), optic nerve hypoplasia (ONH), and hypopituitarism, has had multiple findings added, with uncertain causes, definitions, and limits.

METHOD

Literature review.

RESULTS

SOD is a complex vascular sequence with confounders.

CONCLUSIONS

Proximal anterior cerebral artery trunk disruptions cause overlapping primary effects, giving ONH alone most often, and isolated SPD less. ONH disruptions can spread to pituitary, SPD disruptions to the cerebral cortex, causing schizencephaly and related anomalies. Pituitary defects are rare without ONH, and cortical findings are rare without SPD. Extensions are unidirectional, so isolated pituitary or cortical defects are separate from SOD. Micro- an- ophthalmia, a suggested ONH variant, is not part of SOD. Disruption by-products can affect development, causing cognitive and endocrine issues, and structural anomalies such as corpus callosum thinning, ventriculomegaly, and hippocampal and olfactory findings. Limbic extensions may also contribute to the same structural defects as by-products. Midline CNS developmental anomalies can act as disruptive foci, most likely through vascular variants, but have separate pathogenesis. Relative frequencies of specific pituitary hormone defects change as SOD rates increase. Increasing relative rates of midline CNS developmental defects and cortical anomalies are consistent with rising levels of exogenous exposures sensitizing to midline predispositions.

Approach to the Patient: Management of Pituitary Hormone Replacement Through Transition

Hypopituitarism in childhood is a rare, complex disorder that can present with highly variable phenotypes, which may continue into adult life. Pituitary deficits can evolve over time, with unpredictable patterns resulting in significant morbidity and mortality. Hypopituitarism and hypothalamic dysfunction may be associated with challenging comorbidities such as obesity, learning difficulties, behavioral issues, sleep disturbance, and visual impairment. Transition is the purposeful planned movement of adolescents and young adults with chronic conditions from child-centered to adult-oriented health care systems with a shift from parent- to patient-focused care. To achieve effective transition within a health care setting, the inherent challenges involved in the evolution from a dependent child to an independent adult must be recognized. Transition is a critical time medically for patients with hypopituitarism. Complex issues with respect to puberty, attainment of optimal stature, adherence to treatment, and acceptance of the need for life-sustaining medications need to be addressed. For health care professionals, transition is an opportunity for reassessment of the pituitary deficits and the need for lifelong replacement therapies, often against a background of complex psychological issues. We present 4 illustrative cases of hypopituitarism of differing etiologies with diverse clinical presentations. Diagnostic and management processes from clinical presentation to young adulthood are discussed, with a particular focus on needs and outcomes through transition.

A Novel Splice-Site Deletion in the POU1F1 Gene Causes Combined Pituitary Hormone Deficiency in Multiple Sudanese Pedigrees

Pathogenic variants within the gene encoding the pituitary-specific transcription factor, POU class 1 homeobox 1 (POU1F1), are associated with combined pituitary hormone deficiency (CPHD), including growth hormone, prolactin, and thyrotropin stimulating hormone deficiencies. The aim of the study was to identify genetic aetiology in 10 subjects with CPHD from four consanguineous Sudanese families. Medical history, as well as hormonal and radiological information, was obtained from participants’ medical records. Targeted genetic analysis of the POU1F1 gene was performed in two pedigrees with a typical combination of pituitary deficiencies, using Sanger sequencing, and whole-exome sequencing was performed in the other two pedigrees, where hypocortisolism and additional neurologic phenotypes were also initially diagnosed. In POU1F1 gene (NM_001122757.2) a novel homozygous splice-site deletion—namely, c.744-5_749del—was identified in all 10 tested affected family members as a cause of CPHD. Apart from typical pituitary hormonal deficiencies, most patients had delayed but spontaneous puberty; however, one female had precocious puberty. Severe post-meningitis neurologic impairment was observed in three patients, of whom two siblings had Dyke–Davidoff–Masson syndrome, and an additional distantly related patient suffered from cerebral infarction. Our report adds to the previously reported POU1F1 gene variants causing CPHD and emphasises the importance of genetic testing in countries with high rates of consanguineous marriage such as Sudan. Genetic diagnostics elucidated that the aetiologies of hypopituitarism and brain abnormalities, identified in a subset of affected members, were separate. Additionally, as central hypocortisolism is not characteristic of POU1F1 deficiency, hydrocortisone replacement therapy could be discontinued. Elucidation of a genetic cause, therefore, contributed to the more rational clinical management of hypopituitarism in affected family members.

Congenital hypopituitarism due to novel compound heterozygous POU1F1 gene mutation: A case report and review of the literature

Failure to thrive is one of the most common complaints in the endocrinology and genetics clinic. An 8-month-old girl with presentation of motor developmental delay, failure to thrive, and midline facial defects, with history of hypoglycemia at birth and central congenital hypothyroidism (CCH), was brought to our genetic clinic. Hormone test demonstrated combined pituitary hormone deficiency with growth hormone deficiency (GHD), central hypothyroidism, and hypoprolactinemia. Brain magnetic resonance imaging (MRI) showed anterior pituitary hypoplasia (APH), abnormal pituitary stalk, and preserved posterior pituitary lobe. Whole exome sequence (WES) identified a compound heterozygous mutation of the POU1F1 gene: c.649C>T (p.Arg217Ter) and c.662T>C (p.Ile221Thr), which are de novo mutation and inherited from mother, respectively. The patient's phenotype was consistent clinically with congenital hypopituitarism due to the POU1F1 gene mutation. Based on our literature review, this is the first report of the c.662T>C mutation, to the best of our knowledge. Our study demonstrates the power of WES for early diagnosis of congenital hypopituitarism with its relative phenotype for improving prognosis and preventing irreversible deficit.

POU1F1 mutations in combined pituitary hormone deficiency: differing spectrum of mutations in a Western-Indian cohort and systematic analysis of world literature

CONTEXT

POU1F1 mutations are prevalent in Indian CPHD cohorts. Genotype-phenotype correlation is not well-studied.

AIM

To describe phenotypic and genotypic spectrum of POU1F1 mutations in our CPHD cohort and present systematic review as well as genotype-phenotype analysis of all mutation-positive cases reported in world literature.

METHODS

Retrospective study of POU1F1 mutation-positive patients from a western-Indian center. PRISMA guidelines based pubmed search of published literature of all mutation-positive patients.

RESULTS

Our cohort had 15 POU1F1 mutation-positive patients (9 index, 6 relatives). All had severe GH, TSH and prolactin deficiencies (GHD, TSHD and PD). TSHD was diagnosed earliest followed by GHD (median ages: TSHD-6 months, GHD-3 years), while PD was more variable. Two sisters had central precocious puberty at 7 years of age. Pubic hair was deficient in all post-pubertal patients (females: P1-P2, males: P3-P4). Splice-site/intronic/frameshift mutations were most common, while missense/nonsense mutations were less frequent (33%). Review of world literature yielded 114 patients (82 index patients) from 58 studies. GHD was present in all patients. TSHD was spared in 12.5% and PD in 4.4% patients. Missense/nonsense mutations accounted for 75% of spectrum. Phenotype-genotype analysis revealed higher mean peak-GH levels (1.1 vs 0.2 ng/ml, p = 0.008) and lower prevalence of anterior-pituitary hypoplasia (63.6% vs 86.3%, p = 0.03) in patients with heterozygous than homozygous and compound heterozygous mutations.

CONCLUSIONS

We present largest series of POU1F1 mutation-positive patients. Precocious puberty and defective pubarche are lesser-appreciated phenotypic features. Our mutation spectrum is different from that of world literature. Patients with heterozygous mutations have milder phenotype.

Clinical lessons learned in constitutional hypopituitarism from two decades of experience in a large international cohort

CONTEXT

The international GENHYPOPIT network collects phenotypical data and screens genetic causes of non-acquired hypopituitarism.

AIMS

To describe main phenotype patterns and their evolution through life.

DESIGN

Patients were screened according to their phenotype for coding sequence variations in 8 genes: HESX1, LHX3, LHX4, PROP1, POU1F1, TBX19, OTX2 and PROKR2.

RESULTS

Among 1213 patients (1143 index cases), the age of diagnosis of hypopituitarism was congenital (24%), in childhood (28%), at puberty (32%), in adulthood (7.2%) or not available (8.8%). Noteworthy, pituitary hormonal deficiencies kept on evolving during adulthood in 49 of patients. Growth Hormone deficiency (GHD) affected 85.8% of patients and was often the first diagnosed deficiency. AdrenoCorticoTropic Hormone deficiency rarely preceded GHD, but usually followed it by over 10 years. Pituitary Magnetic Resonance Imaging (MRI) abnormalities were common (79.7%), with 39.4% pituitary stalk interruption syndrome (PSIS). The most frequently associated extrapituitary malformations were ophthalmological abnormalities (16.1%). Prevalence of identified mutations was 7.3% of index cases (84/1143) and 29.5% in familial cases (n = 146). Genetic analysis in 449 patients without extrapituitary phenotype revealed 36 PROP1, 2 POU1F1 and 17 TBX19 mutations.

CONCLUSION

This large international cohort highlights atypical phenotypic presentation of constitutional hypopituitarism, such as post pubertal presentation or adult progression of hormonal deficiencies. These results justify long-term follow-up, and the need for systematic evaluation of associated abnormalities. Genetic defects were rarely identified, mainly PROP1 mutations in pure endocrine phenotypes.

Genetic spectrum and predictors of mutations in four known genes in Asian Indian patients with growth hormone deficiency and orthotopic posterior pituitary: an emphasis on regional genetic diversity

CONTEXT

Regional variation in prevalence of genetic mutations in growth hormone deficiency (GHD) is known.

AIM

Study phenotype and prevalence of mutations in GH1, GHRHR, POU1F1, PROP1 genes in GHD cohort.

METHODS

One hundred and two patients {Isolated GHD (IGHD): 79; combined pituitary hormone deficiency (CPHD): 23} with orthotopic posterior pituitary were included. Auxologic, hormonal and radiological details were studied. All four genes were analysed in IGHD patients. POU1F1 and PROP1 were studied in CPHD patients.

RESULTS

Of 102, 19.6% were familial cases. Height SDS, mean (SD) was - 5.14 (1.63). Peak GH, median (range) was 0.47 ng/ml (0-6.59), 72.5% patients had anterior pituitary hypoplasia (APH). Twenty mutations (novel: 11) were found in 43.1% patients (n = 44, IGHD-36, CPHD-8). GHRHR mutations (n = 32, p.Glu72* = 24) were more common than GH1 mutations (n = 4) in IGHD cohort. POU1F1 mutations (n = 6) were more common than PROP1 mutations (n = 2) in CPHD cohort. With few exceptions, this prevalence pattern is contrary to most studies in world-literature. No patients with peak GH > 4 ng/ml had mutations, signifying it as negative predictor. While many parameters were significant on univariate analysis, only positive family history and lower median peak GH levels were significant predictors of mutations on multivariate analysis in IGHD patients.

CONCLUSION

At variance with world literature, we found reverse predominance of GHRHR over GH1 mutations, POU1F1 over PROP1 mutations and predominance of GHRHR p.Glu72* mutations thus re-affirming the regional diversity in GHD genetics. We report positive and negative predictors of mutations in GHD.

Mutations Within the Transcription Factor PROP1 in a Cohort of Turkish Patients with Combined Pituitary Hormone Deficiency

OBJECTIVE

Mutations of the genes encoding transcription factors which play important roles in pituitary morphogenesis, differentiation and maturation may lead to combined pituitary hormone deficiency (CPHD). PROP1 gene mutations are reported as the most frequent genetic aetiology of CHPD. The aim of this study was to describe the phenotypes of Turkish CPHD patients and define the frequency of PROP1 mutations.

METHODS

Fifty-seven CPHD patients from 50 families were screened for PROP1 mutations. The patients were affected by growth hormone (GH) and additional anterior pituitary hormone deficiencies.

RESULTS

All patients had GH deficiency. In addition, 98.2% had central hypothyroidism, 45.6% had hypogonadotropic hypogonadism, 43.8% had adrenocorticotropic hormone deficiency and 7.1% had prolactin deficiency. Parental consanguinity rate was 50.9% and 14 cases were familial. Mean height standard deviation score (SDS) and weight SDS were -3.8±1.4 and -3.1±2.0, respectively. Of 53 patients with available pituitary imaging, 32 (60.4%) showed abnormalities. None had extra-pituitary abnormalities. Eight index patients had PROP1 gene mutations. Five sporadic patients were homozygous for c.301_302delAG (p.Leu102CysfsTer8) mutation, two siblings had exon 2 deletion, two siblings had complete gene deletion and two siblings were homozygous for the novel c.353A>G (p.Q118R) mutation. The frequency of the PROP1 mutations was 16% in our cohort. Mutation rate was significantly higher in familial cases compared to sporadic cases (42.8% vs 11.6%; p<0.01).

CONCLUSION

Phenotype of patients regarding hormonal deficiencies, pituitary morphology, presence of extra-pituitary findings, family history of CPHD and parental consanguinity are important for deciding which pituitary transcription factor deficiency should be investigated. PROP1 mutation frequencies vary in different populations and its prevalence is high in Turkish CPHD patients.

Unique near-complete deletion of GLI2 in a patient with combined pituitary hormone deficiency and post-axial polydactyly

INTRODUCTION

Combined pituitary hormone deficiency (CPHD) can cause a broad spectrum of health problems, ranging from short stature only, to convulsions or even death. In the majority of patients, the cause is unknown.

METHODS

The idex case had unexplained CPHD, pituitary anomalies on MRI and polydactyly. In the patients and her unaffected parents, we performed SNP array analysis and Whole Exome Sequencing, after candidate gene analysis turned out negative.

RESULTS

We found a unique de novo heterozygous 229.9 kb deletion in the index case on chr. 2q14.2. This deletion covered 12 out of the 13 coding exons of the GLI2 gene, a transcription factor involved in midline formation and previously associated with CPHD. As reported GLI2 deletions and mutations show a large phenotypic variability, we performed a genotype-phenotype analysis. This revealed that GLI2 missense mutations usually present with a 'ppp-only' phenotype (pituitary anomalies ± postaxial polydactyly without brain phenotype), whereas the 'ppp-plus' phenotype (with major brain malformations and/or intellectual disabilities) is more frequent in patients with larger deletions, and those with frameshift mutations/point mutations or splice variants resulting in a stop codon (p < .001).

CONCLUSION

The present case shows that a deletion of the GLI2 gene only (not affecting any of the adjacent genes) causes pituitary anomalies without brain phenotype. This suggests that brain phenotype only occurs when additional genes adjacent to GLI2 are deleted, or when mutations result in truncated GLI2 mRNA/protein. However, due to the lack of functional data for many GLI2 mutations and based on the available information regarding variable penetrance, phenotype-genotype correlations need to be made with caution.

Genetic analysis of adult Slovenian patients with combined pituitary hormone deficiency

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Next generation sequencing panel based on single molecule molecular inversion probes for detecting genetic variants in children with hypopituitarism

BACKGROUND

Congenital Hypopituitarism is caused by genetic and environmental factors. Over 30 genes have been implicated in isolated and/or combined pituitary hormone deficiency. The etiology remains unknown for up to 80% of the patients, but most cases have been analyzed by limited candidate gene screening. Mutations in the PROP1 gene are the most common known cause, and the frequency of mutations in this gene varies greatly by ethnicity. We designed a custom array to assess the frequency of mutations in known hypopituitarism genes and new candidates, using single molecule molecular inversion probes sequencing (smMIPS).

METHODS

We used this panel for the first systematic screening for causes of hypopituitarism in children. Molecular inversion probes were designed to capture 693 coding exons of 30 known genes and 37 candidate genes. We captured genomic DNA from 51 pediatric patients with CPHD (n = 43) or isolated GH deficiency (IGHD) (n = 8) and their parents and conducted next generation sequencing.

RESULTS

We obtained deep coverage over targeted regions and demonstrated accurate variant detection by comparison to whole-genome sequencing in a control individual. We found a dominant mutation GH1, p.R209H, in a three-generation pedigree with IGHD.

CONCLUSIONS

smMIPS is an efficient and inexpensive method to detect mutations in patients with hypopituitarism, drastically limiting the need for screening individual genes by Sanger sequencing.

Genetic screening of regulatory regions of pituitary transcription factors in patients with idiopathic pituitary hormone deficiencies

PURPOSE

Mutation frequencies of PROP1, POU1F1 and HESX1 in patients with combined pituitary hormone deficiencies (CPHD) vary substantially between populations. They are low in sporadic CPHD patients in Western Europe. However, most clinicians still routinely send DNA of their CPHD patients for genetic screening of these pituitary transcription factors. Before we can recommend against screening of PROP1, POU1F1 and HESX1 as part of routine work-up for Western-European sporadic CPHD patients, it is crucial to rule out possible defects in regulatory regions of these genes, which could also disturb the complex process of pituitary organogenesis.

METHODS

The regulatory regions of PROP1, POU1F1 and HESX1 are not covered by Whole Exome Sequencing as they are largely located outside the coding regions. Therefore, we manually sequenced the regulatory regions, previously defined in the literature, of PROP1, POU1F1 and HESX1 among 88 Dutch patients with CPHD. We studied promoter SNPs in relation to phenotypic data.

RESULTS

We found six known SNPs in the PROP1 promoter. In the POU1F1 promoter, we found one new variant and two known SNPs. We did not find any variant in the HESX1 promoter.

CONCLUSION

Although the new POU1F1 variant might explain the phenotype of one patient, the general conclusion of this study is that variants in regulatory regions of PROP1, POU1F1 and HESX1 are rare in patients with sporadic CPHD in the Netherlands. We recommend that genetic screening of these pituitary transcription factors should no longer be part of routine work-up for Western-European, and especially Dutch, sporadic CPHD patients.

Combined pituitary hormone deficiency due to gross deletions in the POU1F1 (PIT-1) and PROP1 genes

Pituitary development depends on a complex cascade of interacting transcription factors and signaling molecules. Lesions in this cascade lead to isolated or combined pituitary hormone deficiency (CPHD). The aim of this study was to identify copy number variants (CNVs) in genes known to cause CPHD and to determine their structure. We analyzed 70 CPHD patients from 64 families. Deletions were found in three Turkish families and one family from northern Iraq. In one family we identified a 4.96 kb deletion that comprises the first two exons of POU1F1. In three families a homozygous 15.9 kb deletion including complete PROP1 was discovered. Breakpoints map within highly homologous AluY sequences. Haplotype analysis revealed a shared haplotype of 350 kb among PROP1 deletion carriers. For the first time we were able to assign the boundaries of a previously reported PROP1 deletion. This gross deletion shows strong evidence to originate from a common ancestor in patients with Kurdish descent. No CNVs within LHX3, LHX4, HESX1, GH1 and GHRHR were found. Our data prove multiplex ligation-dependent probe amplification to be a valuable tool for the detection of CNVs as cause of pituitary insufficiencies and should be considered as an analytical method particularly in Kurdish patients.

Genetics of Combined Pituitary Hormone Deficiency: Roadmap into the Genome Era

The genetic basis for combined pituitary hormone deficiency (CPHD) is complex, involving 30 genes in a variety of syndromic and nonsyndromic presentations. Molecular diagnosis of this disorder is valuable for predicting disease progression, avoiding unnecessary surgery, and family planning. We expect that the application of high throughput sequencing will uncover additional contributing genes and eventually become a valuable tool for molecular diagnosis. For example, in the last 3 years, six new genes have been implicated in CPHD using whole-exome sequencing. In this review, we present a historical perspective on gene discovery for CPHD and predict approaches that may facilitate future gene identification projects conducted by clinicians and basic scientists. Guidelines for systematic reporting of genetic variants and assigning causality are emerging. We apply these guidelines retrospectively to reports of the genetic basis of CPHD and summarize modes of inheritance and penetrance for each of the known genes. In recent years, there have been great improvements in databases of genetic information for diverse populations. Some issues remain that make molecular diagnosis challenging in some cases. These include the inherent genetic complexity of this disorder, technical challenges like uneven coverage, differing results from variant calling and interpretation pipelines, the number of tolerated genetic alterations, and imperfect methods for predicting pathogenicity. We discuss approaches for future research in the genetics of CPHD.

Genetic causes of isolated and combined pituitary hormone deficiency

Research over the last 20 years has led to the elucidation of the genetic aetiologies of Isolated Growth Hormone Deficiency (IGHD) and Combined Pituitary Hormone Deficiency (CPHD). The pituitary plays a central role in growth regulation, coordinating the multitude of central and peripheral signals to maintain the body's internal balance. Naturally occurring mutation in humans and in mice have demonstrated a role for several factors in the aetiology of IGHD/CPHD. Mutations in the GH1 and GHRHR genes shed light on the phenotype and pathogenesis of IGHD whereas mutations in transcription factors such as HESX1, PROP1, POU1F1, LHX3, LHX4, GLI2 and SOX3 contributed to the understanding of CPHD. Depending upon the expression patterns of these molecules, the phenotype may consist of isolated hypopituitarism, or more complex disorders such as septo-optic dysplasia (SOD) and holoprosencephaly. Although numerous monogenic causes of growth disorders have been identified, most of the patients with IGHD/CPHD remain with an explained aetiology as shown by the relatively low mutation detection rate. The introduction of novel diagnostic approaches is now leading to the disclosure of novel genetic causes in disorders characterized by pituitary hormone defects.

Frequency of genetic defects in combined pituitary hormone deficiency: a systematic review and analysis of a multicentre Italian cohort

OBJECTIVE

Combined pituitary hormonal deficiency (CPHD) can result from mutations within genes that encode transcription factors. This study evaluated the frequency of mutations in these genes in a cohort of 144 unrelated Italian patients with CPHD and estimated the overall prevalence of mutations across different populations using a systematic literature review.

MATERIAL AND METHODS

A multicentre study of adult and paediatric patients with CPHD was performed. The PROP1, POU1F1, HESX1, LHX3 and LHX4 genes were analysed for the presence of mutations using direct sequencing. We systematically searched PubMed with no date restrictions for studies that reported genetic screening of CPHD cohorts. We only considered genetic screenings with at least 10 individuals. Data extraction was conducted in accordance with the guidelines set by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

RESULTS

Global mutation frequency in Italian patients with CPHD was 2·9% (4/136) in sporadic cases and 12·5% (1/8) in familial cases. The worldwide mutation frequency for the five genes calculated from 21 studies was 12·4%, which ranged from 11·2% in sporadic to 63% in familial cases. PROP1 was the most frequently mutated gene in sporadic (6·7%) and familial cases (48·5%).

CONCLUSION

The frequency of defects in genes encoding pituitary transcription factors is quite low in Italian patients with CPHD and other western European countries, especially in sporadic patients. The decision of which genes should be tested and in which order should be guided by hormonal and imaging phenotype, the presence of extrapituitary abnormalities and the frequency of mutation for each gene in the patient-referring population.

Molecular analysis of PROP1, POU1F1, LHX3, and HESX1 in Turkish patients with combined pituitary hormone deficiency: a multicenter study

To investigate the specific mutations in PROP1, POU1F1, LHX3, and HESX1 genes in patients with combined pituitary hormone deficiency (CPHD) in Turkey. Seventy-six patients with CPHD were included in this study. Based on clinical, hormonal, and neuro-radiological data, relevant transcription factor genes were evaluated by Sanger sequencing and multiplex ligation-dependent probe amplification. Total frequency of mutations was 30.9 % in patients with CPHD. Frequency was significantly higher in familial patients (p = 0.001). Three different types of mutations in PROP1 gene (complete gene deletion, c.301-302delAG, a novel mutation; IVS1+2T>G) were found in 12 unrelated patients (21.8 %). Mutations in PROP1 gene were markedly higher in familial than in sporadic cases (58.8 vs. 5.3 %, p < 0.001). Homozygous complete gene deletion was the most common mutation in PROP1 gene (8/12) and was identified in six familial patients. Four different homozygous mutations [p.Q4X, novel mutations; exons 1-2 deletion, p.V153F, p.I244S] were detected in POU1F1 gene. Central precocious puberty was firstly observed in a sporadic-male patient with homozygous POU1F1 (p.I244S) mutation. A homozygous mutation in HESX1 gene (p.R160H) was detected in one patient. This study is the first to investigate specific mutations in CPHD patients in Turkey. Complete deletion in PROP1 gene was the most common mutation encountered in patients with CPHD. We believe that the results of this study will contribute to the establishment of genetic screening strategies in Turkey, as well as to the studies on phenotype-genotype correlations and early diagnosis of CPHD patients.

The role of Notch and Hedgehog signaling pathways in pituitary development and pathogenesis of pituitary adenomas

Pituitary adenomas are usually benign tumors that cause symptoms by compression of surrounding structures or impaired hormone secretion. Treatment, whether surgical or medical depends, on the tumor subtype and degree of compression; however, a significant proportion of patients do not achieve optimal control of mass effects or hormonal hypersecretion. Unraveling the pathogenesis of pituitary adenomas is a critical step in the quest for new subcellular treatment targets that will decrease morbidity and mortality related to these tumors. A large diversity of pathogenetic mechanisms has been described so far including deregulation of cell cycle, molecular pathways and angiogenesis. Major signaling pathways such as Notch, Wnt and Hedgehog, which are mainly active in the early phase of pituitary organogenesis and are essential for the development of somatotrophs, lactotrophs thyrotrophs and corticotrophs, have been implicated in the pathogenesis of pituitary adenomas. In this review we present novel data regarding the role of Notch and Hedgehog regulatory networks in pituitary development and pathogenesis of pituitary adenomas.

Prenatal determinants of optic nerve hypoplasia: review of suggested correlates and future focus

Optic nerve hypoplasia (ONH), a congenital malformation characterized by an underdeveloped optic nerve, is a seemingly epidemic cause of childhood blindness and visual impairment with associated lifelong morbidity. Although the prenatal determinants of ONH are unknown, early case reports have led to a longstanding speculation that risky health behaviors (e.g., prenatal use of recreational drugs, alcohol) are a likely culprit. There has yet to be a systematic review of the epidemiology of ONH to assess the common prenatal features that may help focus research efforts in the identification of likely prenatal correlates. A review of the past 50 years of epidemiologic research was conducted to examine the prenatal features linked with ONH and provide direction for future research. There are select prominent prenatal features associated with ONH: young maternal age and primiparity. Commonly implicated prenatal exposures (recreational or pharmaceutical drugs, viral infection, etc.) were rare or uncommon in large cohort studies of ONH and therefore unlikely to be major contributors to ONH. Familial cases and gene mutations are rare. The preponderance of young mothers and primiparity among cases of ONH is striking, although the significance is unclear. Recent research suggests a potential role for prenatal nutrition, weight gain, and factors of deprivation. With the rapidly increasing prevalence of ONH, future research should focus on investigating the relevance of young maternal age and primiparity and exploring the recently suggested etiologic correlates in epidemic clusters of ONH.

Vertical transmission of hypopituitarism: critical importance of appropriate interpretation of thyroid function tests and levothyroxine therapy during pregnancy

BACKGROUND

Typically, newborns with congenital hypothyroidism are asymptomatic at birth, having been exposed to euthyroid mothers. However, hypopituitarism may be associated with central hypothyroidism, preserved fertility, and autosomal dominant inheritance, requiring increased attention to thyroid management during pregnancy.

PATIENT FINDINGS

A woman with a history of growth hormone deficiency and central hypothyroidism gave birth to a term male neonate appropriate for gestational age. Due to low thyrotropin (TSH) in the second trimester, the levothyroxine dose was decreased by the obstetrician, and free T4 was low throughout the latter half of pregnancy. The neonatal laboratory evaluation showed central hypothyroidism with a low T4 of 2.1 μg/dL (4.5-11.5) and an inappropriately normal TSH of 0.98 uIU/mL (0.5-4.5); undetectable growth hormone, IGF-I, and IGFBP3; a normal cortisol level; and a normal gonadotropin surge. After initiation of levothyroxine in the first week, both tone and feeding tolerance improved. However, the patient was found to have hearing loss, gross motor delay, and speech delay.

SUMMARY

In this report, we review a case of vertical transmission of a dominant negative POU1F1 mutation in which fetal abnormalities due to the hypothyroxinemic state during gestation may have been exacerbated by a decrease in the mother's levothyroxine dose based on a low TSH in early gestation. Both mother and fetus were unable to synthesize sufficient thyroid hormone, which may be responsible for the patient's clinical presentation.

CONCLUSION

This case underscores several important points in the management of women with hypopituitarism. First, it is important that patients and clinicians are both aware of the differences in etiology, as well as appropriate screening and treatment, of primary versus central hypothyroidism. Second, it is necessary to monitor the thyroid hormone status closely during pregnancy to prevent fetal sequelae of maternal hypothyroidism. Third, genetic screening of patients with combined pituitary hormone deficiency is necessary, so that prenatal genetic counseling may be an option for expecting parents.

PROP-1 gene mutations in a 63-year-old woman presenting with osteoporosis and hyperlipidaemia

PROP-1 gene mutations have been reported as a cause of combined pituitary hormone deficiency. Physical and hormonal phenotypes of affected individuals are variable. We report a 63-year-old female who presented with osteoporosis. She was short, did not enter puberty spontaneously and had primary amenorrhea. Biochemical evaluation revealed secondary hypothyroidism and mixed hyperlipidaemia, while dynamic testing of pituitary function was diagnostic of hypopituitarism. Bone density in the lumbar spine disclosed osteoporosis. DNA analysis showed that the patient was homozygote for the R73H mutation of the PROP-1 gene. The unfavourable long-term course of an untreated patient with PROP-1 gene mutation emphasizes the need for early aetiologic classification and proper management and follow-up of patients with short stature and/or disturbances of pubertal development.

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.

Functional SNPs within the intron 1 of the PROP1 gene contribute to combined growth hormone deficiency (CPHD)

CONTEXT

Mutations within the PROP1 gene represent one of the main causes of familial combined pituitary hormone deficiency (CPHD). However, most of the cases are sporadic with an unknown genetic cause.

OBJECTIVE

The aim of this study was the search for low penetrance variations within and around a conserved regulatory element in the intron 1 of PROP1, contributing to a multifactorial form of the disease in sporadic patients.

METHODS AND PATIENTS

A fragment of 570 bp encompassing the conserved region was sequenced in 107 CPHD patients and 294 controls, and an association study was performed with the four identified variants, namely c.109+435G>A (rs73346254), c.109+463C>T (rs4498267), c.109+768C>G (rs4431364), and c.109+915_917ins/delTAG (rs148607624). The functional role of the associated polymorphisms was evaluated by luciferase reporter gene expression analyses and EMSA.

RESULTS

A statistically significant increased frequency was observed in the patients for rs73346254A (P = 5 × 10(-4)) and rs148607624delTAG (P = 0.01) alleles. Among all the possible allele combinations, only the haplotype bearing both risk alleles showed a significantly higher frequency in the patients vs. controls (P = 4.7 × 10(-4)) and conferred a carrier risk of 4.19 (P = 1.2 × 10(-4)). This haplotype determined a significant decrease of the luciferase activity in comparison with a basal promoter and the other allelic combinations in GH4C and MCF7 cells (P = 4.6 × 10(-6); P = 5.5 × 10(-4), respectively). The EMSA showed a differential affinity for nuclear proteins for the alternative alleles of the two associated variations.

CONCLUSIONS

Variations with a functional significance conferring susceptibility to CPHD have been identified in the PROP1 gene, indicating a multifactorial origin of this disorder in sporadic cases.

Two novel mutations in the POU1F1 gene generate null alleles through different mechanisms leading to combined pituitary hormone deficiency

BACKGROUND

  Mutations in the POU1F1 gene severely affect the development and function of the anterior pituitary gland and lead to combined pituitary hormone deficiency (CPHD).

OBJECTIVE

  The clinical and genetic analysis of a patient presenting with CPHD and functional characterization of identified mutations.

PATIENT

  We describe a male patient with extreme short stature, learning difficulties, anterior pituitary hypoplasia, secondary hypothyroidism and undetectable prolactin, growth hormone (GH) and insulin-like growth factor 1 (IGF1), with normal random cortisol.

DESIGN

  The POU1F1 coding region was amplified by PCR and sequenced; the functional consequence of the mutations was analysed by cell transfection and in vitro assays.

RESULTS

  Genetic analysis revealed compound heterozygosity for two novel putative loss of function mutations in POU1F1: a transition at position +3 of intron 1 [IVS1+3nt(A>G)] and a point mutation in exon 6 resulting in a substitution of arginine by tryptophan (R265W). Functional analysis revealed that IVS1+3nt(A>G) results in a reduction in the correctly spliced POU1F1 mRNA, which could be corrected by mutations of the +4, +5 and +6 nucleotides. Analysis of POU1F1(R265W) revealed complete loss of function resulting from severely reduced protein stability.

CONCLUSIONS

  Combined pituitary hormone deficiency in this patient is caused by loss of POU1F1 function by two novel mechanisms, namely aberrant splicing (IVS1+3nt (A>G) and protein instability (R265W). Identification of the genetic basis of CPHD enabled the cessation of hydrocortisone therapy without the need for further assessment for evolving endocrinopathy.

Detection of genetic hypopituitarism in an adult population of idiopathic pituitary insufficiency patients with growth hormone deficiency

Idiopathic pituitary insufficiency (IPI) is diagnosed in 10% of all hypopituitary patients. There are several known and unknown aetiologies within the IPI group. The aim of this study was to investigate an adult IPI population for genetic cause according a screening schedule. From files of 373 GH deficient (GHD) patients on GH replacement 50 cases with IPI were identified. Of the 39 patients that approved to the study, 25 patients were selected for genetic investigation according to phenotype and 14 patients were not further tested, as sporadic isolated GHD (n = 9) and GHD with diabetes insipidus (n = 5) have low probability for a known genetic cause. Genotyping of all coding exons of HESX1, LHX4, PROP1, POU1F1 and GH1 genes were performed according to a diagnostic algorithm based on clinical, hormonal and neuroradiological phenotype. Among the 25 patients, an overall rate of 8% of mutations was found, and a 50% rate in familial cases. Among two sibling pairs, one pair that presented with complete anterior pituitary insufficiency, had a compound heterozygous PROP1 gene mutation (codons 117 and 120: exon 3 p Phe 117 Ile (c349 T>A) and p Arg 120 Cys (c358 C>T)) with a phenotype of very late onset ACTH-insufficiency. In the other sibling pair and in the sporadic cases no mutation was identified. This study suggests that currently known genetic causes are rare in sporadic adult IPI patients, and that systematic genetic screening is not needed in adult-onset sporadic cases of IPI. Conversely, familial cases are highly suspect for genetic causes.

Congenital hypopituitarism due to POU1F1 gene mutation

POU1F1 (Pit-1; Gene ID 5449) is an anterior pituitary transcriptional factor, and POU1F1 mutation is known to cause anterior pituitary hypoplasia, growth hormone and prolactin deficiency and various degree of hypothyroidism. We report here a patient who presented with growth failure and central hypothyroidism since early infancy. However, treatment with thyroxine gave no effect and he subsequently developed calf muscle pseudohypertrophy (Kocher-Debre-Semelaigne syndrome), elevation of creatinine kinase, dilated cardiomyopathy and pericardial effusion. Final diagnosis was made by combined pituitary function test and sequencing analysis that revealed POU1F1 gene C.698T > C (p.F233S) mutation. The rarity of the disease can result in delayed diagnosis and treatment.

[Genetic background of inherited multiple pituitary hormone deficiency. Mutations of PROP1 gene 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 transcription factors in the aetiology of combined pituitary hormone deficiency

The somatotropic axis is the central postnatal regulator of longitudinal growth. One of its major components--growth hormone--is produced by the anterior lobe of the pituitary, which also expresses and secretes five additional hormones (prolactin, thyroid stimulating hormone, follicle stimulating hormone, luteinizing hormone, adrenocorticotropic hormone). Proper development of the pituitary assures the regulation of critical processes such as metabolic control, puberty and reproduction, stress response and lactation. Ontogeny of the adenohypophysis is orchestrated by inputs from neighbouring tissues, cellular signalling molecules and transcription factors. Perturbation of expression or function of these factors has been implicated in the aetiology of combined pituitary hormone deficiency (CPHD). Mutations within the genes encoding for the transcription factors LHX3, LHX4, PROP1, and POU1F1 (PIT1) that act at different stages of pituitary development result in unique patterns of hormonal deficiencies reflecting their differential expression during organogenesis. In the case of LHX3 and LHX4 the phenotype may include extra-pituitary manifestations due to the function of these genes/proteins outside the pituitary gland. The remarkable variability in the clinical presentation of affected patients indicates the influence of the genetic background, environmental factors and possibly stochastic events. However, in the majority of CPHD cases the aetiology of this heterogeneous disease remains unexplained, which further suggests the involvement of additional genes. Identification of these factors might also help to close the gaps in our understanding of pituitary development, maintenance and function.

Molecular analysis of the PROP1 and HESX1 genes in patients with septo-optic dysplasia and/or pituitary hormone deficiency

OBJECTIVE: The present study aimed at evaluating the PROP1 and HESX1 genes in a group of patients with septo-optic dysplasia (SOD) and pituitary hormone deficiency (combined - CPHD; isolated GH deficiency - GHD). Eleven patients with a clinical and biochemical presentation consistent with CPHD, GHD or SOD were evaluated. SUBJECTS AND METHODS: In all patients, the HESX1 gene was analyzed by direct sequence analysis and in cases of CPHD the PROP1 gene was also sequenced. RESULTS: A polymorphism (1772 A > G; N125S) was identified in a patient with SOD. We found three patients carrying the allelic variants 27 T > C; A9A and 59 A > G; N20S in exon 1 of the PROP1 gene. Mutations in the PROP1 and HESX1 genes were not identified in these patients with sporadic GHD, CPHD and SOD. CONCLUSION: Genetic alterations in one or several other genes, or non-genetic mechanisms, must be implicated in the pathogenic process.

Genetic regulation of pituitary gland development in human and mouse

Normal hypothalamopituitary development is closely related to that of the forebrain and is dependent upon a complex genetic cascade of transcription factors and signaling molecules that may be either intrinsic or extrinsic to the developing Rathke's pouch. These factors dictate organ commitment, cell differentiation, and cell proliferation within the anterior pituitary. Abnormalities in these processes are associated with congenital hypopituitarism, a spectrum of disorders that includes syndromic disorders such as septo-optic dysplasia, combined pituitary hormone deficiencies, and isolated hormone deficiencies, of which the commonest is GH deficiency. The highly variable clinical phenotypes can now in part be explained due to research performed over the last 20 yr, based mainly on naturally occurring and transgenic animal models. Mutations in genes encoding both signaling molecules and transcription factors have been implicated in the etiology of hypopituitarism, with or without other syndromic features, in mice and humans. To date, mutations in known genes account for a small proportion of cases of hypopituitarism in humans. However, these mutations have led to a greater understanding of the genetic interactions that lead to normal pituitary development. This review attempts to describe the complexity of pituitary development in the rodent, with particular emphasis on those factors that, when mutated, are associated with hypopituitarism in humans.

Effects of genetic variability of the caprine homeobox transcription factor HESX1 gene on performance traits

HESX1 plays a key role in the development of the forebrain and pituitary gland and produces potential effects on performance traits. The objective of this study was to detect and assess the associations of the possible polymorphisms of six loci within HESX1 gene with performance traits in Chinese 1,119 goats. Only one novel SNP (NM_001494116:g.307049A > G) locating on IVS1 + 348A > G was identified and detected by HaeIII forced-RFLP-PCR. The frequencies of allele "G" varied from 0.025 to 0.245 in analyzed populations with the Hardy-Weinberg equilibrium (P > 0.05). Genotypic and allelic frequencies were found to be significantly different in four breeds (chi(2) = 147.674, df = 6, P < 0.001; chi(2) = 157.250, df = 3, P < 0.001, respectively), implying that the distribution of genotypic and allelic frequencies of goat HESX1 gene was significantly associated with different goat utilities (cashmere, meat and dairy). Association analysis results revealed no significant effects of caprine HESX1 gene on body sizes in XNSN population (P > 0.05) and cashmere traits in IMWC population (P > 0.05). Significant statistical of HESX1 gene with body weight was found (*P < 0.05). The genotype AA showed significantly higher body weight than those of AG in 2-year-old age (*P < 0.05), while the AA genotype was senior to AG genotype in 4-year-old body weight trait (*P < 0.05). These suggestions indicated that the HESX1 gene has significant effect on goat body weight depending on ages, which is accordance with the function repressor of the HESX1.

Refining clinical phenotypes in septo-optic dysplasia based on MRI findings

Septo-optic dysplasia (SOD) is a heterogeneous brain midline anomaly associated with ophthalmological, endocrinological, and/or neurodevelopmental symptoms. The clinical phenotype correlates with abnormal brain magnetic resonance imaging (MRI) findings. However, variations of the septum pellucidum (SP) appearance and their clinical impact have not been studied in depth. Sixty-eight patients with optic nerve hypoplasia (ONH) were investigated for the presence of associated SP anomalies and correlations between clinical findings and their MRI abnormalities established. Thirty patients had either complete (n = 22) or partial (n = 8) absence of the SP. Pituitary hormone deficiencies were present in 64% or 25% of the cases, respectively. Neurological symptoms did not occur in patients with SP remnants or unilateral ONH. Hippocampus abnormalities (43%) that have not been described before in SOD and falx abnormalities (17%) correlated significantly with neurological symptoms and developmental delay (p < 0.05 and p < 0.01, respectively). Maternal age at birth was low (21.2 years) and drug abuse during pregnancy was reported in 27% of the patients. Twelve patients with pituitary anomaly and ONH but normal SP showed similar clinical and MRI features, and were classified as SOD-like. The remaining 26 patients were not assigned to SOD. We conclude that unilateral ONH and SP remnants are associated with a milder SOD phenotype. Hippocampus abnormalities and falx abnormalities seem to constitute important features of severe clinical disease, irrespective of SP appearance. Our anamnestic data support the hypothesis of vascular disruption during embryogenesis.

Molecular analysis of PROP1, PIT1, HESX1, LHX3, and LHX4 shows high frequency of PROP1 mutations in patients with familial forms of combined pituitary hormone deficiency

Combined Pituitary Hormone Deficiency (CPHD) is a prevalent disease in Neuroendocrinology services. The genetic form of CPHD may originate from mutations in pituitary transcription factor (PTF) genes and the pituitary image in these cases may give a clue of what PTF is most probably mutated: defects in LHX4 are usually associated with ectopic posterior pituitary (EPP); defects in LHX3, PIT1, and PROP1, with normally placed posterior pituitary (NPPP); HESX1 mutations are associated with both.

OBJECTIVE

To identify mutations in PTF genes in patients with idiopathic hypopituitarism followed in our service, based on the presence or absence of EPP on sellar MRI.

METHODS

Forty patients with idiopathic hypopituitarism (36 families, 9 consanguineous), followed in the Neuroendocrinology Outpatient Clinic of UNIFESP, Brazil, were submitted to sequencing analyses of PTF genes as follows: LHX3, HESX1, PIT1, and PROP1 were sequenced in patients with NPPP (26/40) and HESX1 and LHX4 in patients with EPP (14/40).

RESULTS

We identified only PROP1 mutations in 9 out of 26 patients with CPHD and NPPP (35%). Since eight of them came from 4 consanguineous families, the prevalence of PROP1 mutations was higher when only consanguineous families were considered (44%, 4/9). At the end of the study, we decided to sequence PROP1 in patients with EPP, just to confirm that they were not candidates for PROP1 mutations. No patients with EPP had PROP1 or other PTF mutations.

CONCLUSIONS

Patients with idiopathic CPHD and NPPP, born from consanguineous parents, are the strong candidates for PROP1 mutations. Other developmental gene(s) may be involved in the genesis of idiopathic hypopituitarism associated with EPP.

Leber congenital amaurosis: genes, proteins and disease mechanisms

Leber congenital amaurosis (LCA) is the most severe retinal dystrophy causing blindness or severe visual impairment before the age of 1 year. Linkage analysis, homozygosity mapping and candidate gene analysis facilitated the identification of 14 genes mutated in patients with LCA and juvenile retinal degeneration, which together explain approximately 70% of the cases. Several of these genes have also been implicated in other non-syndromic or syndromic retinal diseases, such as retinitis pigmentosa and Joubert syndrome, respectively. CEP290 (15%), GUCY2D (12%), and CRB1 (10%) are the most frequently mutated LCA genes; one intronic CEP290 mutation (p.Cys998X) is found in approximately 20% of all LCA patients from north-western Europe, although this frequency is lower in other populations. Despite the large degree of genetic and allelic heterogeneity, it is possible to identify the causative mutations in approximately 55% of LCA patients by employing a microarray-based, allele-specific primer extension analysis of all known DNA variants. The LCA genes encode proteins with a wide variety of retinal functions, such as photoreceptor morphogenesis (CRB1, CRX), phototransduction (AIPL1, GUCY2D), vitamin A cycling (LRAT, RDH12, RPE65), guanine synthesis (IMPDH1), and outer segment phagocytosis (MERTK). Recently, several defects were identified that are likely to affect intra-photoreceptor ciliary transport processes (CEP290, LCA5, RPGRIP1, TULP1). As the eye represents an accessible and immune-privileged organ, it appears to be uniquely suitable for human gene replacement therapy. Rodent (Crb1, Lrat, Mertk, Rpe65, Rpgrip1), avian (Gucy2D) and canine (Rpe65) models for LCA and profound visual impairment have been successfully corrected employing adeno-associated virus or lentivirus-based gene therapy. Moreover, phase 1 clinical trials have been carried out in humans with RPE65 deficiencies. Apart from ethical considerations inherently linked to treating children, major obstacles for the treatment of LCA could be the putative developmental deficiencies in the visual cortex in persons blind from birth (amblyopia), the absence of sufficient numbers of viable photoreceptor or RPE cells in LCA patients, and the unknown and possibly toxic effects of overexpression of transduced genes. Future LCA research will focus on the identification of the remaining causal genes, the elucidation of the molecular mechanisms of disease in the retina, and the development of gene therapy approaches for different genetic subtypes of LCA.

[Clinical and genetic aspects of combined pituitary hormone deficiencies]

DEFINITION

Congenital hypopituitarism is characterized by multiple pituitary hormone deficiency, including somatotroph, thyrotroph, lactotroph, corticotroph or gonadotroph deficiencies, due to mutations of pituitary transcription factors involved in pituitary ontogenesis.

INCIDENCE

Congenital hypopituitarism is rare compared with the high incidence of hypopituitarism induced by pituitary adenomas, transsphenoidal surgery or radiotherapy. The incidence of congenital hypopituitarism is estimated to be between 1:3000 and 1:4000 births.

CLINICAL SIGNS

Clinical presentation is variable, depending on the type and severity of deficiencies and on the age at diagnosis. If untreated, main symptoms include short stature, cognitive alterations or delayed puberty.

DIAGNOSIS

A diagnosis of combined pituitary hormone deficiency (CPHD) must be suspected when evident causes of hypopituitarism (sellar tumor, postsurgical or radioinduced hypopituitarism...) have been ruled out. Clinical, biological and radiological work-up is very important to better determine which transcription factor should be screened. Confirmation is provided by direct sequencing of the transcription factor genes.

AETIOLOGY

Congenital hypopituitarism is due to mutations of several genes encoding pituitary transcription factors. Phenotype varies with the factor involved: PROP1 (somatolactotroph, thyrotroph, gonadotroph and sometimes corticotroph deficiencies; pituitary hyper and hypoplasia), POU1F1 (somatolactotroph and thyrotroph deficiencies, pituitary hypoplasia), HESX1 (variable pituitary deficiencies, septo-optic dysplasia), and less frequently LHX3 (somatolactotroph, thyrotroph and gonadotroph deficiencies, limited head and neck rotation) and LHX4 (variable pituitary deficiencies, ectopic neurohypophysis, cerebral abnormalities).

MANAGEMENT

An appropriate replacement of hormone deficiencies is required. Strict follow-up is necessary because patients develop new deficiencies (for example late onset corticotroph deficiency in patients with PROP1 mutations). GENETIC COUNSELLING: Type of transmission varies with the factor and the mutation involved (recessive transmission for PROP1 and LHX3, dominant for LHX4, autosomal or recessive for POU1F1 and HESX1).

PROGNOSIS

It is equivalent to patients without pituitary deficiencies if treatment is started immediately when diagnosis is confirmed, and if a specialized follow-up is performed.

Developmental disorders of the hypothalamus and pituitary gland associated with congenital hypopituitarism

The pituitary gland is a complex organ secreting six hormones from five different cell types. It is the end product of a carefully orchestrated pattern of expression of signalling molecules and transcription factors. Naturally occurring and transgenic murine models have demonstrated a role for many of these molecules in the aetiology of congenital hypopituitarism. These include the transcription factors HESX1, PROP1, POU1F1, LHX3, LHX4, PITX1, PITX2, SOX2 and SOX3. The expression pattern of these transcription factors dictates the phenotype that results when the gene encoding the relevant transcription factor is mutated. The highly variable phenotype may consist of isolated hypopituitarism or more complex disorders such as septo-optic dysplasia and holoprosencephaly. However, the overall incidence of mutations in known transcription factors in patients with hypopituitarism is low, indicating that many genes remain to be identified; characterization of these will further elucidate the pathogenesis of this complex condition and also shed light on normal pituitary development and function.

Highly conserved non-coding sequences and the 18q critical region for short stature: a common mechanism of disease?

Background

Isolated growth hormone deficiency (IGHD) and multiple pituitary hormone deficiency (MPHD) are heterogeneous disorders with several different etiologies and they are responsible for most cases of short stature. Mutations in different genes have been identified but still many patients did not present mutations in any of the known genes. Chromosomal rearrangements may also be involved in short stature and, among others, deletions of 18q23 defined a critical region for the disorder. No gene was yet identified.

Methodology/Principal Findings

We now report a balanced translocation X;18 in a patient presenting a breakpoint in 18q23 that was surprisingly mapped about 500 Kb distal from the short stature critical region. It separated from the flanking SALL3 gene a region enriched in highly conserved non-coding elements (HCNE) that appeared to be regulatory sequences, active as enhancers or silencers during embryonic development.

Conclusion

We propose that, during pituitary development, the 18q rearrangement may alter expression of 18q genes or of X chromosome genes that are translocated next to the HCNEs. Alteration of expression of developmentally regulated genes by translocation of HCNEs may represent a common mechanism for disorders associated to isolated chromosomal rearrangements.

HESX1 mutations are an uncommon cause of septooptic dysplasia and hypopituitarism

CONTEXT

Mutations in the transcription factor HESX1 have previously been described in association with septooptic dysplasia (SOD) as well as isolated defects of the hypothalamic-pituitary axis.

OBJECTIVE

Given that previous screening was carried out by SSCP detection alone and limited to coding regions, we performed an in-depth genetic analysis of HESX1 to establish the true contribution of HESX1 genetic defects to the etiology of hypopituitarism.

DESIGN

Nonfamilial patients (724) with either SOD (n = 314) or isolated pituitary dysfunction, optic nerve hypoplasia, or midline neurological abnormalities (n = 410) originally screened by SSCP were rescreened by heteroduplex detection for mutations in the coding and regulatory regions of HESX1. In addition, direct sequencing of HESX1 was performed in 126 patients with familial hypopituitarism from 66 unrelated families and in 11 patients born to consanguineous parents.

PATIENTS

All patients studied had at least one of the three classical features associated with SOD (optic nerve hypoplasia, hypopituitarism, midline forebrain defects).

RESULTS

Novel sequence changes identified included a functionally significant heterozygous mutation at a highly conserved residue (E149K) in a patient with isolated GH deficiency and digital abnormalities. The overall incidence of coding region mutations within the cohort was less than 1%.

CONCLUSIONS

Mutations within HESX1 are a rare cause of SOD and hypopituitarism. However, the large number of familial patients with SOD in whom no mutations were identified is suggestive of an etiological role for other genetic factors. Furthermore, we have found that within our cohort SOD is associated with a reduced maternal age compared with isolated defects of the hypothalamopituitary axis.

Panhypopituitarism: genetic versus acquired etiological factors

OBJECTIVE

Mutations in the genes encoding pituitary transcription factors (mainly PROP1, POUF1 and HESX1) are responsible for familial combined pituitary hormone deficiency (CPHD) and septo-optic dysplasia (SOD) while only a low percentage of mutations are the cause of sporadic forms. Indeed, it has been suggested that environmental rather than genetic factors could be important in the pathogenesis of CPHD.

PATIENTS AND METHODS

Thirty-six sporadic patients diagnosed with CPHD or SOD were included in the study. All coding exons and intron-exon boundary regions of PROP1, POUF1 and HESX1 were amplified by PCR and subsequently sequenced.

RESULTS

Two novel missense mutations in the HESX1 gene (Q117P, K176T) were identified in two patients. Polymorphisms in PIT1 and PROP1 were also detected. A higher percentage of breech delivery in male patients with CPHD versus females was observed.

CONCLUSIONS

The low percentage of mutations found in the most common transcription factors involved in CPHD show that a better characterization of hormonal and morphological phenotypes is necessary for patients with CPHD included in genetic studies, and other genetic or non-genetic factors have to be taken into account.

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

BACKGROUND

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.

METHODS

Clinical follow-up and molecular analysis of PROP1 in two adult brothers with CPHD, born from consanguineous parents, and not treated until late adulthood.

RESULTS

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.

CONCLUSIONS

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.

High prevalence of PROP1 gene mutations in Hungarian patients with childhood-onset combined anterior pituitary hormone deficiency

Combined pituitary hormone deficiency is characterized by the impaired production of pituitary hormones, commonly including growth hormone. The pathomechanism of the childhood-onset form of this disorder may involve germline mutations of genes encoding pituitary transcription factors, of which PROP1 gene mutations have been studied most extensively. However, controversy exists about the significance of PROP1 gene mutations, as both low and high frequencies have been reported in these patients. Because the different results may be related to differences in patient populations and/or the variability of clinical phenotypes, we performed the present study to examine the prevalence and spectrum of PROP1 gene mutations in 35 patients with non-acquired childhood-onset growth hormone deficiency combined with at least one other anterior pituitary hormone deficiency. Genetic testing indicated the presence of disease-causing mutations in exons 2 and 3 of the PROP1 gene in 15 patients (43% of all patients; homozygous mutations in 10 patients and compound heterozygous mutations in 5 patients). Comparison of clinical data of patients with and without PROP1 gene mutations failed to show significant differences, except an earlier growth retardation detected in patients with PROP1 gene mutations. In one patient with PROP1 gene mutation, radiologic imaging showed an enlargement of the anterior lobe of the pituitary, whereas the other patients had hypoplastic or normal pituitary gland. All patients with PROP1 gene mutations had normal posterior pituitary lobe by radiologic imaging. These results indicate that using our inclusion criteria for genetic testing, PROP1 gene mutations can be detected in a high proportion of Hungarian patients with non-acquired childhood-onset growth hormone deficiency combined with at least one other anterior pituitary hormone defect.

Family-based study of markers at the 5'-flanking region of the human dopamine transporter gene reveals potential association with schizophrenic psychoses

The dopamine hypothesis of schizophrenia proposes an inherited or acquired presynaptic hyperactivity of dopaminergic neurons. The human dopamine transporter gene (hSLC6A3; hDAT) represents one major mechanism for the termination of dopaminergic neurotransmission. This study examines the degree of genetic association of the 5'-untranslated region (5'-UTR) of the hSLC6A3 to schizophrenia in a family-based association design. Five single nucleotide polymorphisms (SNPs) derived by a previous systematic mutation scan approximately 1.2 kb of the 5'-UTR of the hSLC6A3 locus were genotyped for transmission disequilibrium between 82 index cases (56 males) with schizophrenia and their biological parents. We observed no preferential transmission of alleles from heterozygous parents to affected offspring. Five estimated haplotypes accounted for a frequency of 90% in the index cases, and were identical in cases and non-transmitted parental control haplotypes. Distinct five-locus-genotypes accumulated in schizophrenia compared to parental controls at P-value 0.0038 with odds-ratio of 2.02 (95% CI 0.99-4.14). In conclusion, our present findings support the genetic involvement of distinct hSLC6A3 genotypes in schizophrenia. We propose replication in extended samples and examination of the functional relevance of the associated genotypes on human dopamine transporter expression.

Association study of 5'-UTR polymorphisms of the human dopamine transporter gene with manic depression

OBJECTIVES

To determine the degree of association of five single nucleotide polymorphisms at the 5'-untranslated region (5'-UTR) of the human dopamine transporter gene (hSLC6A3; hDAT1) in bipolar affective disorder.

METHODS

In a case-control design study, the polymorphisms were genotyped for allelic and genotypic distribution between 105 index cases (50 males) with bipolar affective disorder according to DSM IV and 199 unaffected control subjects (120 males).

RESULTS

At the 5'-UTR locus of hSLC6A3, no significant allelic or genotypic differences were observed between index cases and controls. However, distinct 5-locus genotypes accumulated in subjects with bipolar affective disorder compared to control subjects (p = 0.029, odds ratio 1.84, 95% confidence interval 1.12-3.02).

CONCLUSIONS

In conclusion, our data do not provide evidence for a major role of the 5'-UTR of the dopamine transporter gene in bipolar affective disorder. A minor contribution of distinct genotypes may be possible and warrants replication in extended samples.

Genetic screening of combined pituitary hormone deficiency: experience in 195 patients

CONTEXT

Mutations in transcription factors result in combined pituitary hormone deficiency (CPHD).

OBJECTIVE

A genetic screening strategy, based on endocrine and neuroradiological phenotype according to published knowledge, was applied to establish the prevalence of gene defects in each category of patients and provide a useful framework for clinicians to determine the genetic etiology and recurrence risks for individuals and families.

DESIGN

One hundred ninety-five CPHD patients from the international GENHYPOPIT network were studied, according to their phenotype, for POU1F1, PROP1, LHX3, LHX4, and HESX1.

PATIENTS

Patients selected had two pituitary hormone deficiencies or at least one deficiency with intracerebral malformations.

RESULTS

Total prevalence of mutations was 13.3 and 52.4% in 20 patients with familial CPHD history. No mutation of HESX1 was observed in 16 patients harboring septooptic dysplasia. A mutation of LHX4 gene, previously reported, was found in one familial case from 39 patients bearing pituitary stalk interruption syndrome. In 109 patients without extrapituitary abnormalities, 20 had PROP1 mutations, including eight patients with a family history of CPHD. Among 20 patients without pituitary stalk interruption syndrome, no LHX3 gene defect was found, even with a neck rotation deficit. One POU1F1 gene defect was found in one patient presenting the rare postpubertal association of thyrotroph (TSH deficiency) and somatotroph (GH deficiency) deficits.

CONCLUSIONS

Mutation of PROP1 gene remains the first to be looked for, and POU1F1 mutations should be sought in GH deficiency and TSH deficiency postpubertal population without extrapituitary malformations. Identification of gene defects allows early treatment of any deficit and prevention of their potentially fatal consequences. Genotyping appears highly beneficial at an individual and familial level.

Pathological optic-disc cupping

PURPOSE OF REVIEW

Pathological optic-disc cupping is most often caused by glaucoma, but may be seen in many less-common neuro-ophthalmic conditions. The goal of this article is to examine a host of entities causing optic-disc cupping, present key differentiating characteristics and pathophysiologies, and outline diagnostic approaches.

RECENT FINDINGS

Multiple entities not associated with elevated intraocular pressure or glaucomatous optic-nerve disease may result in pathologic optic-nerve excavation. Even with the photography and imaging of today, it is still difficult for the clinician to accurately diagnose other causes of optic-disc cupping. Up to 20% of patients may be misdiagnosed and treated for glaucoma due to misinterpretation of the optic-disc cupping. Newer forms of imaging including optical coherence tomography may assist the clinician in decision making. A scrutinizing history, close observation of disc appearance, and the vasculature will aid in the diagnosis of glaucoma or other entity of optic-disc cupping.

SUMMARY

Optic-disc cupping is a consequence of myriad disorders. Knowledge of the anatomy and vasculature of the disc is quintessential to the understanding of how, why, when, and what type of optic-disc cupping occurs in various conditions. Cupping can be seen with neurological processes, including benign tumors, which are treatable. Patient history, visual fields assessment, and funduscopic findings are the key to unlocking the diagnosis of glaucomatous versus nonglaucomatous optic-disc cupping. As clinicians, we must remain vigilant and receptive to the findings of potentially ominous forms of nonglaucomatous optic-disc cupping.

The role of transcription factors implicated in anterior pituitary development in the aetiology of congenital hypopituitarism

The anterior pituitary gland is a central regulator of growth, reproduction and homeostasis, and is the end-product of a carefully orchestrated pattern of expression of signalling molecules and transcription factors leading to the development of this complex organ secreting six hormones from five different cell types. Naturally occurring and transgenic murine models have demonstrated a role for many of these molecules in the aetiology of combined pituitary hormone deficiency (CPHD). These include the transcription factors HESX1, PROP1, POU1FI, LHX3, LHX4, TBX19 (TPIT), SOX3 and SOX2. The expression pattern of these transcription factors, their interaction with co-factors and their impact on target genes dictate the phenotype that results when the gene encoding the relevant transcription factor is mutated. The highly variable phenotype may consist of isolated hypopituitarism, or more complex disorders such as septo-optic dysplasia (SOD) and holoprosencephaly. Since mutations in any one transcription factor are uncommon, and since the overall incidence of mutations in known transcription factors is low in patients with CPHD, it is clear that many genes remain to be identified, and characterization of these will further elucidate the pathogenesis of these complex conditions, and also shed light on normal pituitary development.