Identification of SLC20A1 and SLC15A4 among other genes as potential risk factors for combined pituitary hormone deficiency.

PURPOSE: Combined pituitary hormone deficiency (CPHD) is characterized by a malformed or underdeveloped pituitary gland resulting in an impaired pituitary hormone secretion. Several transcription factors have been described in its etiology, but defects in known genes account for only a small proportion of cases. METHODS: To identify novel genetic causes for congenital hypopituitarism, we performed exome-sequencing studies on 10 patients with CPHD and their unaffected parents. Two candidate genes were sequenced in further 200 patients. Genotype data of known hypopituitary genes are reviewed. RESULTS: We discovered 51 likely damaging variants in 38 genes; 12 of the 51 variants represent de novo events (24%); 11 of the 38 genes (29%) were present in the E12.5/E14.5 pituitary transcriptome. Targeted sequencing of two candidate genes, SLC20A1 and SLC15A4, of the solute carrier membrane transport protein family in 200 additional patients demonstrated two further variants predicted as damaging. We also found combinations of de novo (SLC20A1/SLC15A4) and transmitted variants (GLI2/LHX3) in the same individuals, leading to the full-blown CPHD phenotype. CONCLUSION: These data expand the pituitary target genes repertoire for diagnostics and further functional studies. Exome sequencing has identified a combination of rare variants in different genes that might explain incomplete penetrance in CPHD.

Roles of the LHX3 and LHX4 LIM-homeodomain factors in pituitary development.

The LHX3 and LHX4 LIM-homeodomain transcription factors play essential roles in pituitary gland and nervous system development. Mutations in the genes encoding these regulatory proteins are associated with combined hormone deficiency diseases in humans and animal models. Patients with these diseases have complex syndromes involving short stature, and reproductive and metabolic disorders. Analyses of the features of these diseases and the biochemical properties of the LHX3 and LHX4 proteins will facilitate a better understanding of the molecular pathways that regulate the development of the specialized hormone-secreting cells of the mammalian anterior pituitary gland.

Comparison of adrenal function tests in children--the glucagon stimulation test allows the simultaneous assessment of adrenal function and growth hormone response in children.

The accurate assessment of adrenal function is necessary in many children with suspicion of pituitary insufficiency. The objective of this study was to evaluate the adrenal response during the glucagon stimulation test (GST) and its diagnostic utility in children. A total of 290 children, aged 10.1 +/- 5.0 years, were evaluated for adrenal function using the corticotrophin releasing hormone (CRH) test, the GST, and/or the insulin tolerance test (ITT). Glucagon stimulation provoked a substantial rise in cortisol and adrenocorticotropin (ACTH) that was independent of gender, age, or underlying growth hormone deficiency. There were no differences in peak cortisol levels in the GST compared to the CRH test in pair-wise intra-individual analyses in children with both tests performed within one year (615.4 +/- 30.5 vs 602.8 +/- 22.4 nmol/l, n=52). Similarly, there were no differences in the cortisol response between the ITT and CRH test. Peak cortisol levels in the CRH test correlated with the GST and the ITT. The magnitude of ACTH response, in contrast, was highest in the ITT with a 9.8-fold increase over baseline, while the increase in the GST (3.1-fold) and CRH test (1.6-fold) were more subtle. Since there is controversy concerning reliable cut-off values for adrenal function tests in children, we analyzed cut off levels in 186 children, including 26 children with adrenal insufficiency, using the CRH test. A peak cortisol level of 450 nmol/l provided the best balance of sensitivity (88.5%) and specificity (86.8%), while higher cut-off levels did not increase sensitivity but lost in specificity. In summary, the GST constitutes an1 equally sensitive test for the assessment of adrenal function in children that is not confounded by anthropometric parameters and is generally not accompanied by major side effects. It allows the simultaneous assessment of corticotroph and somatotroph function and may thus constitute a valuable alternative to the ITT.

A novel FoxD3 Variant Is Associated With Vitiligo and Elevated Thyroid Auto-Antibodies.

CONTEXT: Vitiligo frequently coincides with autoimmune endocrinopathies, particularly Hashimoto's thyroiditis (HT). Genetic susceptibility may underlie this coincident occurrence. One candidate region is the autoimmunity susceptibility locus on chromosome 1, which encompasses forkhead transcription factor D3 (FoxD3), a gene involved in embryonal melanogenesis. We identified a promotor variant (rs78645479) in an index case of vitiligo + HT + candidiasis and evaluated its clinical and functional relevance. DESIGN: We genotyped 281 patients with variable autoimmune endocrinopathies: HT, Graves' disease (GD), type 1 diabetes (T1D), Addison's disease (AD), autoimmune polyglandular syndrome (APS), and/or vitiligo and 1858 controls. Furthermore, we experimentally assessed the effect of the variant on promotor activity and assessed the expression of FoxD3 in human thyroid tissue samples. RESULTS: Patients with vitiligo had a higher frequency of the risk allele (30%) compared with healthy controls (18.2%). In addition, the variant was associated with the incidence of elevated anti-TPO antibodies and anti-Tg antibodies, but not with TSH, FT3, or FT4 levels and also not with GD, T1D, AD, or APS. Functionally, the variant increased transcriptional activity in Jurkat and in Hek293 cells. We confirmed gene expression of FoxD3 in human thyroid tissue, which seemed elevated in thyroid tissue samples of some patients with GD and nonautoimmune goiter but not in patients with HT. CONCLUSION: In addition to a possible association of rs78645479 in FoxD3 with vitiligo, our data on the association of this FoxD3 variant with thyroid autoantibodies suggest a potential involvement of FoxD3 in thyroid immunoregulation.

PROP1 mutations cause progressive deterioration of anterior pituitary function including adrenal insufficiency: a longitudinal analysis.

Mutations in the PROP1 gene are the most frequent genetic defects in patients with combined pituitary hormone insufficiency. However, controversy exists about the timing and extent of pituitary insufficiency, and it remains unclear whether adrenal failure is a typical feature of this condition. We performed a retrospective longitudinal analysis of nine patients with PROP1 mutations who were under medical supervision at our clinic for 15.7 +/- 3.4 yr. All patients initially presented with growth failure (height sd score, -3.7 +/- 0.3) at a mean age of 4.9 +/- 0.8 yr. They were first diagnosed with GH and TSH deficiency, and replacement therapy was instituted at 6.1 +/- 1.1 and 6.8 +/- 1.2 yr, respectively. All seven patients who reached pubertal age required sex hormone substitution at 15.0 +/- 0.7 yr. Repeated functional testing of the anterior pituitary axes revealed a progressive decline with age in peak levels of GH, TSH, prolactin, and LH/FSH. All patients developed at least partial adrenal insufficiency, with a gradual decline of the function of the pituitary adrenal axis and eventually required substitution with hydrocortisone at a mean age of 18.4 +/- 3.5 yr. It is concluded that anterior pituitary function in patients with PROP1 mutations deteriorates progressively and includes adrenal insufficiency as a feature of this condition, which has important clinical relevance in childhood and adolescence.

New N-terminal located mutation (Q4ter) within the POU1F1-gene (PIT-1) causes recessive combined pituitary hormone deficiency and variable phenotype.

OBJECTIVE: Growth is an inherent property of life. About 10% of the congenital forms of growth retardation and short stature are genetically caused. Beside the gene involved in direct GH-production, there are different candidate genes important for appropriate pituitary development causing combined pituitary hormone deficiency (CPHD). However, severe growth retardation and failure to thrive remain the leading reason for medical assessment in these patients. PATIENTS AND METHODS: We report two siblings of a healthy but consanguineous Malaysian family presenting with severe short stature caused by CPHD with a variable phenotype. Importantly, at the beginning the girl presented with isolated GHD, whereas the boy was hypothyroid. As the most common gene alterations responsible for CPHD are within either the PROP-1- or the POU1F1- (PIT-1)-gene these two genes were further studied. RESULTS: Subsequent sequencing of the six exons of the POU1F1-gene allowed the identification of a new N-terminal mutation (Q4ter) in these two children. A substitution of C to T induced a change from a glutamine (CAA) to a stop codon (TAA) in exon 1 of the PIT-1 protein. Both affected children were homozygous for the mutation, whereas the mother and father were heterozygous. CONCLUSION: We describe two children with autosomal recessive inherited CPHD caused by a new N-terminal located mutation within the PUO1F1-gene. The clinical history of these two children underline the phenotypic variability and support the fact that children with any isolated and/or combined PHD need to be closely followed as at an any time other hormonal deficiencies may occur. In addition, molecular analysis of the possible genes involved might be most helpful for the future follow-up.

Associations between pituitary imaging abnormalities and clinical and biochemical phenotypes in children with congenital growth hormone deficiency: data from an international observational study.

BACKGROUND/AIMS: Magnetic resonance imaging (MRI) is used to investigate the etiology of growth hormone deficiency (GHD). This study examined relationships between MRI findings and clinical/hormonal phenotypes in children with GHD in the observational Genetics and Neuroendocrinology of Short Stature International Study, GeNeSIS. METHODS: Clinical presentation, hormonal status and first-year GH response were compared between patients with pituitary imaging abnormalities (n = 1,071), patients with mutations in genes involved in pituitary development/GH secretion (n = 120) and patients with idiopathic GHD (n = 7,039). RESULTS: Patients with hypothalamic-pituitary abnormalities had more severe phenotypes than patients with idiopathic GHD. Additional hormonal deficiencies were found in 35% of patients with structural abnormalities (thyroid-stimulating hormone > adrenocorticotropic hormone > luteinizing hormone/follicle-stimulating hormone > antidiuretic hormone), most frequently in patients with septo-optic dysplasia (SOD). Patients with the triad [ectopic posterior pituitary (EPP), pituitary aplasia/hypoplasia and stalk defects] had a more severe phenotype and better response to GH treatment than patients with isolated abnormalities. The sex ratio was approximately equal for patients with SOD, but there was a significantly higher proportion of males (approximately 70%) in the EPP, pituitary hypoplasia, stalk defects, and triad categories. CONCLUSION: This large, international database demonstrates the value of classification of GH-deficient patients by the presence and type of hypothalamic-pituitary imaging abnormalities. This information may assist family counseling and patient management.

Effects of obesity on human sexual development.

Puberty is a period of physical and psychological maturation, with long-term effects on health. During the 20(th) century, a secular trend towards earlier puberty occurred in association with improvements in nutrition. The worldwide pandemic of childhood obesity has renewed interest in the relationship between body composition in childhood and the timing and tempo of puberty. Limited evidence suggests that earlier puberty is associated with a tendency towards central fat deposition; therefore, pubertal status needs to be carefully considered in the categorization of childhood and adolescent overweight and obesity. In the other direction, rapid early weight gain is associated with advanced puberty in both sexes, and a clear association exists between increasing BMI and earlier pubertal development in girls. Evidence in boys is less clear, with the majority of studies showing obesity to be associated with earlier puberty and voice break, although a subgroup of boys with obesity exhibits late puberty, perhaps as a variation of constitutional delay in growth and puberty. The possible mechanisms linking adiposity with pubertal timing are numerous, but leptin, adipocytokines and gut peptides are central players. Other possible mediators include genetic variation and environmental factors such as endocrine disrupting chemicals. This Review presents current evidence on this topic, highlighting inconsistencies and opportunities for future research.