Context: The X-linked immunoglobulin superfamily, member 1 (IGSF1), gene is highly expressed in the hypothalamus and in pituitary cells of the POU1F1 lineage. Human loss-of-function mutations in... Show moreContext: The X-linked immunoglobulin superfamily, member 1 (IGSF1), gene is highly expressed in the hypothalamus and in pituitary cells of the POU1F1 lineage. Human loss-of-function mutations in IGSF1 cause central hypothyroidism, hypoprolactinemia, and macroorchidism. Additionally, most affected adults exhibit higher than average IGF-1 levels and anecdotal reports describe acromegaloid features in older subjects. However, somatotrope function has not yet been formally evaluated in this condition.Objective: We aimed to evaluate the role of IGSF1 in human and murine somatotrope function.Patients, Design, and Setting: We evaluated 21 adult males harboring hemizygous IGSF1 loss-of-function mutations for features of GH excess, in an academic clinical setting.Main Outcome Measures: We compared biochemical and tissue markers of GH excess in patients and controls, including 24-hour GH profile studies in 7 patients. Parallel studies were undertaken in male Igsf1-deficient mice and wild-type littermates.Results: IGSF1-deficient adult male patients demonstrated acromegaloid facial features with increased head circumference as well as increased finger soft-tissue thickness. Median serum IGF-1 concentrations were elevated, and 24-hour GH profile studies confirmed 2- to 3-fold increased median basal, pulsatile, and total GH secretion. Male Igsf1-deficient mice also demonstrated features of GH excess with increased lean mass, organ size, and skeletal dimensions and elevated mean circulating IGF-1 and pituitary GH levels.Conclusions: We demonstrate somatotrope neurosecretory hyperfunction in IGSF1-deficient humans and mice. These observations define a hitherto uncharacterized role for IGSF1 in somatotropes and indicate that patients with IGSF1 mutations should be evaluated for long-term consequences of increased GH exposure. Show less
In rare disease research, most randomized prospective clinical trials can only use limited number of patients and are comprised of highly heterogeneous populations. Therefore, it is crucial to... Show moreIn rare disease research, most randomized prospective clinical trials can only use limited number of patients and are comprised of highly heterogeneous populations. Therefore, it is crucial to report the results in such a manner that it allows for comparison of treatment effectiveness and biochemical control between studies. The aim of this review was to investigate the current methods that are being applied to measure and report growth hormone (GH) and insulin-like growth factor-1 (IGF-1) as markers for drug effectiveness in clinical acromegaly research. A systematic search of recent prospective and retrospective studies, published between 2012 and 2017, that studied the effects of somatostatin analogues or dopamine agonists in acromegaly patients was performed. The markers of interest were GH, IGF-1, and the suppression of GH after an oral glucose tolerance test (OGTT). Additionally, the use of pharmacokinetic (PK) measurements in these studies was analyzed. The sampling design, cut-off for biochemical control, reported units, and used summary statistics were summarized. A total of 49 articles were selected out of the 263 screened abstracts. IGF-1 concentrations were measured in all 49 studies, GH in 45 studies, and an OGTT was performed in 11 studies. A wide range of different cut-off values and sampling designs were used to determine biochemical control in acromegaly patients. The summary statistics were reported in various ways, with the percentage of biochemical control most frequently used. Nine studies sampled the PK at one or more time points. Non-compartmental analyses were commonly performed on the available PK data. The way GH and IGF-1 are measured and reported in acromegaly research varies considerably. A consensus on how to report study results would enable better comparisons between studies, thereby improving evidence based decision making to optimize treatment in acromegaly. OBJECTIVE SEARCH STRATEGY RESULTS CONCLUSIONS Show less
Conclusion: Simplified sampling schemes, particularly a day profile, can be used for the estimation of GH secretion in patients with active acromegaly and under medical treatment. However, in... Show moreConclusion: Simplified sampling schemes, particularly a day profile, can be used for the estimation of GH secretion in patients with active acromegaly and under medical treatment. However, in healthy controls and patients after successful surgery, prolonged and frequent sampling schemes, at least at 2-hour intervals, reliably reflect 24-hour secretion. Show less
Background: Loss-of-function mutations in immunoglobulin superfamily member 1 (IGSF1) cause an X-linked syndrome of central hypothyroidism, macroorchidism, delayed pubertal testosterone rise,... Show moreBackground: Loss-of-function mutations in immunoglobulin superfamily member 1 (IGSF1) cause an X-linked syndrome of central hypothyroidism, macroorchidism, delayed pubertal testosterone rise, variable prolactin deficiency and variable partial GH deficiency in childhood. The clinical features and gene expression pattern suggest a pivotal role for IGSF1 in the pituitary, but detailed knowledge on pituitary hormone secretion in this syndrome is lacking. We therefore aimed to study the 24-hour pituitary hormone secretion in male patients with IGSF1 deficiency. Methods: We collected blood samples every 10 min for 24 h in eight adult male IGSF1-deficient patients and measured circulating TSH, prolactin and gonadotropins. Deconvolution, modified cosinor and approximate entropy analyses were applied to quantify secretion rates, diurnal rhythmicity and regularity of hormone release. Results were compared to healthy controls matched for age and body mass index. Results: Compared to healthy controls, IGSF1-deficient patients showed decreased pulsatile secretion of TSH with decreased disorderliness and reduced diurnal variation. Basal and pulsatile secretion of FSH was increased by over 200%, while LH secretion did not differ from healthy controls. We observed a bimodal distribution of prolactin secretion, i.e. severe deficiency in three and increased basal and total secretion in the other five patients. Conclusion: The altered TSH secretion pattern is consistent with the previously hypothesized defect in thyrotropin-releasing hormone signaling in IGSF1 deficiency. However, the phenotype is more extensive and includes increased FSH secretion without altered LH secretion as well as either undetectable or increased prolactin secretion. (C) 2015 S. Karger AG, Basel Show less
Objective: Arthropathy is an invalidating complication of acromegaly. Although acromegalic arthropathy shares features with primary osteoarthritis, joint spaces are widened rather than narrowed in... Show moreObjective: Arthropathy is an invalidating complication of acromegaly. Although acromegalic arthropathy shares features with primary osteoarthritis, joint spaces are widened rather than narrowed in patients with long term cure of acromegaly. The late effects of acromegaly on hand joints have not been characterized. Therefore the objective of the current study was to assess joint space widths of hand joints in patients with long-term control of acromegaly and to identify factors associated with joint space width.Design: Cross-sectional studyMethods: Cross-sectional study in 89 patients(age 58±12yr, 49% women) with long-term controlled acromegaly and 471 controls without hand symptoms(age 46±12yr, 42% women). Radiological joint space widths of individual hand joints were measured by automated image analysis.Results: Patients had wider mean joint spaces than controls: MCP-joints were ~24%, PIP-joints ~21%, and DIP-joints ~20% wider (patients vs controls; p<0.001 for all joints). Mean joint space width exceeded the 95th percentile of the values obtained in controls in 64% of patients. Higher IGF-1 and GH concentrations at diagnosis were associated with larger joint space widths (adjusted ß for pretreatment GH in tertiles:0.09(95%CI 0.03-1.84) and for IGF-1 in tertiles 0.14(95%CI 0.05-0.23) at the MCP-joints in acromegalic patients. In male, but not in female, patients increased joint space widths were associated with more self-reported pain(p=0.02).Conclusions: Using a new semi-automated image analysis of hand radiographs, acromegalic patients with long-term disease control appeared to have increased joint spaces of all hand joints. Joint space widths were positively related to disease activity at diagnosis, but not to duration of follow-up, suggesting irreversible cartilage hypertrophy. Irreversible cartilage hypertrophy may partly explain persisting hand complaints, despite long-term disease control. Show less
