Outcomes of annual surveillance imaging in an adult and paediatric cohort of succinate dehydrogenase B mutation carriers.

OBJECTIVE: For 'asymptomatic carriers' of the succinate dehydrogenase subunit B (SDHB) gene mutations, there is currently no consensus as to the appropriate modality or frequency of surveillance imaging. We present the results of a surveillance programme of SDHB mutation carriers. DESIGN: Review of clinical outcomes of a surveillance regimen in patients identified to have an SDHB gene mutation, based on annual MRI, in a single UK tertiary referral centre. PATIENTS: A total of 92 patients were identified with an SDHB gene mutation. a total of 27 index patients presented with symptoms, and 65 patients were identified as asymptomatic carriers. MEASUREMENTS: Annual MRI of the abdomen, with alternate year MRI of the neck, thorax and pelvis. Presence of an SDHB-related tumour included paraganglioma (PGL), phaeochromocytoma (PCC), renal cell carcinoma (RCC) and gastrointestinal stromal tumour (GIST). RESULTS: A total of 43 PGLs, eight PCCs and one RCC occurred in the 27 index patients (23 solitary, four synchronous, five metachronous). A further 15 SDHB-related tumours (11 PGLs, three RCCs, one GIST) were identified in the asymptomatic carriers on surveillance screening (25% of screened carriers): 10 on the first surveillance imaging and five on subsequent imaging 2-6 years later. A total of 11 patients had malignant disease. CONCLUSIONS: SDHB-related tumours are picked up as early as 2 years after initial negative surveillance scan. We believe the high malignancy rate and early identification rate of tumours justifies the use of 1-2 yearly imaging protocols and MRI-based imaging could form the mainstay of surveillance in this patient group thereby minimizing radiation exposure.

Diagnosing unilateral primary aldosteronism - comparison of a clinical prediction score, computed tomography and adrenal venous sampling.

CONTEXT: In patients with primary aldosteronism (PA), adrenalectomy is potentially curative for those correctly identified as having unilateral excessive aldosterone production. It has been suggested that a recently developed and published clinical prediction score (CPS) may correctly identify some patients as having unilateral disease, without recourse to adrenal venous sampling. OBJECTIVE: We have applied the CPS to a large cohort of PA patients with defined and documented outcomes. We also incorporated a minor modification to the CPS and a radiological grading score (RGS) into our analysis to assess whether its performance could be augmented. RESULTS: A total of 75 patients with a robust diagnosis following bilateral adrenal venous cannulation and/or strictly defined surgical outcome were analysed. Applying the CPS to this group of patients produced a sensitivity of 38·8% and a specificity of 88·5% of correctly identifying unilateral aldosterone production. Using a suggested modification to the CPS, in which different levels of hypokalaemia were given different weightings, the sensitivity rose to 40·8%, with an identical specificity. Using the RGS alone improved sensitivity to 91·7%, but specificity was reduced to 62·5%. CONCLUSION: Applying the recently developed CPS to this cohort of patients, it was not possible to reproduce the 100% specificity reported in the original publication. Using the modified score or incorporating the RGS did not improve its performance. In this cohort, we were unable to show superiority of the CPS over an imaging-based strategy. CPS may have a role in guiding clinical decision-making, especially in those whose adrenal venous sampling (AVS) has been unsuccessful.

Long-term remission and recurrence rates in Cushing's disease: predictive factors in a single-centre study.

OBJECTIVE: To investigate the early and late outcomes of patients with Cushing's disease (CD) submitted to a neurosurgical procedure as first-line treatment. DESIGN: In this single-centre retrospective case notes study, 131 patients with CD with a minimum follow-up period of 6 years (124 operated by transsphenoidal surgery (TSS) and seven by the transcranial approach) were studied. Apparent immediate cure: post-operative 0900 h serum cortisol level <50 nmol/l; remission: cortisol insufficiency or restoration of 'normal' cortisol levels with resolution of clinical features; and recurrence: dexamethasone resistance and relapse of hypercortisolaemic features. RESULTS: In patients operated by TSS, remission of hypercortisolaemia was found in 72.8% of 103 microadenomas and 42.9% of 21 macroadenomas, with recurrence rates 22.7 and 33.3% respectively with a 15-year mean follow-up (range, 6-29 years). Of 27 patients with microadenomas operated after 1991, with positive imaging and pathology, 93% obtained remission with 12% recurrence. In multivariate analysis, the time needed to achieve recovery of hypothalamo-pituitaryadrenal axis was the only significant predictor of recurrence; all patients who recurred showed recovery within 3 years from surgery: 31.3% of patients had total hypophysectomy with no recurrence; 42% of patients with selective adenomectomy and 26.5% with hemi-hypophysectomy showed recurrence rates of 31 and 13% respectively (χ(2)=6.275, P=0.03). Strict remission criteria were not superior in terms of the probability of recurrence compared with post-operative normocortisolaemia. CONCLUSIONS: Lifelong follow-up for patients with CD appears essential, particularly for patients who have shown rapid recovery of their axis. The strict criteria previously used for 'apparent cure' do not appear to necessarily predict a lower recurrence rate.

Multiple tandem splicing silencer elements suppress aberrant splicing within the long exon 26 of the human Apolipoprotein B gene.

BACKGROUND: Apolipoprotein B (APOB) is an integral component of the chylomicron and the atherogenic lipoproteins LDL and Lp(a). Exon 26 of the APOB pre-mRNA is unusually long at 7,572 nt and is constitutively spliced. It is also subject to RNA editing in the intestine, which generates a shortened isoform, APOB48, assembled exclusively into chylomicrons. Due to its length, exon 26 contains multiple pseudo splice sites which are not spliced, but which conform to the degenerate splice site consensus. RESULTS: We demonstrate that these pseudo splice sites are repressed by multiple, tandem splicing silencers distributed along the length of exon 26. The distribution of these elements appears to be heterogeneous, with a greater frequency in the middle 4,800 nt of the exon. CONCLUSION: Repression of these splice sites is key to maintaining the integrity of exon 26 during RNA splicing and therefore the correct expression of both isoforms of APOB.

Evaluation of SDHB, SDHD and VHL gene susceptibility testing in the assessment of individuals with non-syndromic phaeochromocytoma, paraganglioma and head and neck paraganglioma.

OBJECTIVES: Research studies have reported that about a third of individuals with phaeochromocytoma/paraganglioma (PPGL) have an inherited predisposition, although the frequency of specific mutations can vary between populations. We evaluated VHL, SDHB and SDHD mutation testing in cohorts of patients with non-syndromic PPGL and head and neck paraganglioma (HNPGL). DESIGN: Prospective, observational evaluation of NHS practice. PATIENTS: Individuals with PPGL/HNPGL referred to a supraregional genetics testing service over a 10-year period. MEASUREMENTS: Clinical (age, tumour site, malignancy, etc.), mutation frequencies and characteristics. RESULTS: A total of 501 probands with PPGL (n = 413) or HNPGL (n = 88) were studied. Thirty-one percent of patients with PPGL presented had a pathogenic mutation in SDHB, SDHD or VHL. Mutation detection rates were highest in those with a positive family history (62%), malignancy (53%), multiple tumours (33%) or PGL (44%). Twenty-eight percent of individuals with a single sporadic phaeochromocytoma had a mutation. Overall, 63% of patients with HNPGL had a mutation (92% of those with a family history, 89% of those with multicentric tumours and 34% of those with a single sporadic HNPGL). Penetrance was calculated in 121 SDHB mutation-positive probands and 187 of their mutation-positive relatives. Most relatives were asymptomatic and lifetime penetrance in non-proband SDHB mutation carriers was <50%. CONCLUSIONS: Practice-based evaluations of genetic testing in PPGL reveal high mutation detection rates. Although clinical criteria can be used to prioritize mutation testing, mutations were detected in 'low risk groups' indicating a need for comprehensive and inexpensive genetic testing strategies for PPGL and HNPGL.

DNA diagnostics and exon skipping.

The predominate form of DNA diagnostics remains nucleic acid sequencing in the research and clinical setting. While DNA sequencing allows a mutation to be correctly identified, only RNA sequencing can confirm the effect of that mutation on the resulting mRNA transcript. In the absence of RNA sequencing, predictions are reliant on either experimental studies or bioinformatic modelling. While each of these approaches provides insights into cellular splicing choices, of which exon skipping is but one, both possess inherent weaknesses. A method which is able to integrate and appropriately weigh the various factors influencing cellular splicing choices into an accurate, comprehensive modelling tool still remains elusive.In this overview chapter, the current methods utilised for DNA diagnostics and the impact of the emerging next-generation sequencing techniques are considered. We explore why RNA remains a problematic medium with which to work. To understand how exon skipping can be predicted from a DNA sequence, the key cis-acting elements influencing splicing are reviewed. Finally, the current methods used to predict exon skipping including RNA-based studies, experimental studies, and bioinformatic modelling approaches are outlined.

A prospective evaluation of postural stimulation testing, computed tomography and adrenal vein sampling in the differential diagnosis of primary aldosteronism.

CONTEXT: In primary aldosteronism (PA), discriminating unilateral from bilateral disease is crucial because adrenalectomy is frequently curative in the former case but rarely helps in the latter. Various series have reported the utility of postural stimulation testing (PST), cross-sectional imaging and adrenal vein sampling (AVS) in the assessment of PA, but most of these studies were retrospective. OBJECTIVE: To prospectively determine the diagnostic utility of PST, AVS and computed tomography (CT) using a radiological scoring system in the assessment of PA in a tertiary centre, as well as to document the incidence of autonomous cortisol cosecretion. DESIGN AND SETTING: Fifty consecutive patients with PA underwent PST, CT, AVS and a low-dose dexamethasone suppression test with measurement of serum cortisol at 48 h. For patients who underwent surgery, histological confirmation, and a normal postoperative serum aldosterone concentration and plasma renin activity were taken as evidence for unilateral disease. For other patients, results from successful adrenal vein sampling were the diagnostic evidence against which CT and PST were assessed. RESULTS: Postural stimulation testing had a sensitivity and specificity of 44-56% and 71-75%, respectively. CT had an overall sensitivity and specificity of 77% and 80%, respectively, rising to 100% sensitivity and specificity if there was a single, discrete macronodule with an unequivocally normal contralateral gland. Evidence of cosecretion of cortisol occurred in 14% of patients. CONCLUSIONS: Preliminary experience is presented of an objective radiological scoring system for selecting patients with PA for AVS. PST provides little, if any, useful additional information. A significant minority of patients with PA exhibit evidence of cortisol cosecretion, which may have implications for perioperative management.

Single photon emission computed tomography (SPECT)/computed tomography using Iodine-123 in patients with differentiated thyroid cancer: additional value over whole body planar imaging and SPECT.

OBJECTIVE: The aim of the study was to assess the diagnostic performance of co-registered single photon emission computed tomography (SPECT)/computed tomography (CT) compared to Iodine-123 whole body gamma camera (WBGC) imaging and to SPECT alone in patients with differentiated thyroid cancer. METHODS: WBGC and SPECT/CT (n=85) imaging of the neck and thorax was performed in 79 consecutive patients. Three experienced observers reviewed: i) WBGC images followed by ii) SPECT alone, and iii) co-registered SPECT/CT. Foci of increased radioiodine uptake were classified on a five-point scale. Biopsy, other imaging modalities, and clinical follow-up served as the reference standard. RESULTS: Twenty-two patients had local recurrence or metastatic thyroid cancer (11 were radioiodine negative), 9 had remnant thyroid tissue, and 54 had no evidence of disease. When classifying equivocal, probably, and definitely malignant findings as positive for malignancy, the sensitivity, specificity, positive predictive value, and negative predictive value were as follows: 41, 68, 31, and 77% for WBGC imaging; 45, 89, 59, and 82% for WBGC plus SPECT imaging; and 50, 100, 100, and 85% for WBGC plus SPECT/CT imaging respectively. The specificity was improved by the addition of SPECT (P=0.0002) and SPECT/CT (P<0.0001) than to WBGC imaging. SPECT/CT was also more specific than WBGC plus SPECT imaging (P=0.016). In a study-based analysis, SPECT/CT provided additional diagnostic information in 42% (36/85) of cases. SPECT/CT provided further characterization in 70% (63/90) of foci and improved the diagnostic confidence of all three observers. CONCLUSION: The addition of SPECT/CT significantly improved the diagnostic information over Iodine-123 WBGC imaging and WBGC plus SPECT imaging alone.

Diagnosis and localisation of insulinoma: the value of modern magnetic resonance imaging in conjunction with calcium stimulation catheterisation.

CONTEXT: Preoperative localisation of insulinoma improves cure rate and reduces complications, but may be challenging. OBJECTIVE: To review diagnostic features and localisation accuracy for insulinomas. DESIGN: Cross-sectional, retrospective analysis. SETTING: A single tertiary referral centre. PATIENTS: Patients with insulinoma in the years 1990-2009, including sporadic tumours and those in patients with multiple endocrine neoplasia syndromes. INTERVENTIONS: Patients were identified from a database, and case notes and investigation results were reviewed. Tumour localisation by computed tomography (CT), magnetic resonance imaging (MRI), octreotide scanning, endoscopic ultrasound (EUS) and calcium stimulation was evaluated. MAIN OUTCOME MEASURE(S): Insulinoma localisation was compared to histologically confirmed location following surgical excision. RESULTS: Thirty-seven instances of biochemically and/or histologically proven insulinoma were identified in 36 patients, of which seven were managed medically. Of the 30 treated surgically, 25 had CT (83.3%) and 28 had MRI (90.3%), with successful localisation in 16 (64%) by CT and 21 (75%) by MRI respectively. Considered together, such imaging correctly localised 80% of lesions. Radiolabelled octreotide scanning was positive in 10 out of 20 cases (50%); EUS correctly identified 17 lesions in 26 patients (65.4%). Twenty-seven patients had calcium stimulation testing, of which 6 (22%) did not localise, 17 (63%) were correctly localised, and 4 (15%) gave discordant or confusing results. CONCLUSIONS: Preoperative localisation of insulinomas remains challenging. A pragmatic combination of CT and especially MRI predicts tumour localisation with high accuracy. Radionuclide imaging and EUS were less helpful but may be valuable in selected cases. Calcium stimulation currently remains useful in providing an additional functional perspective.

Diagnosis: imaging of pheochromocytomas and paragangliomas.

Pheochromocytomas and paragangliomas are rare tumors, but their investigation and management are complex and expensive, both in terms of time and resources. a novel prospective study systematically compared different imaging techniques, and the results provide clinicians with valuable help in deciding the appropriate imaging strategy for patients with pheochromocytomas or paragangliomas.

Tumor risks and genotype-phenotype-proteotype analysis in 358 patients with germline mutations in SDHB and SDHD.

Succinate dehydrogenase B (SDHB) and D (SDHD) subunit gene mutations predispose to adrenal and extraadrenal pheochromocytomas, head and neck paragangliomas (HNPGL), and other tumor types. We report tumor risks in 358 patients with SDHB (n=295) and SDHD (n=63) mutations. Risks of HNPGL and pheochromocytoma in SDHB mutation carriers were 29% and 52%, respectively, at age 60 years and 71% and 29%, respectively, in SDHD mutation carriers. Risks of malignant pheochromocytoma and renal tumors (14% at age 70 years) were higher in SDHB mutation carriers; 55 different mutations (including a novel recurrent exon 1 deletion) were identified. No clear genotype-phenotype correlations were detected for SDHB mutations. However, SDHD mutations predicted to result in loss of expression or a truncated or unstable protein were associated with a significantly increased risk of pheochromocytoma compared to missense mutations that were not predicted to impair protein stability (most such cases had the common p.Pro81Leu mutation). Analysis of the largest cohort of SDHB/D mutation carriers has enhanced estimates of penetrance and tumor risk and supports in silicon protein structure prediction analysis for functional assessment of mutations. The differing effect of the SDHD p.Pro81Leu on HNPGL and pheochromocytoma risks suggests differing mechanisms of tumorigenesis in SDH-associated HNPGL and pheochromocytoma.

A single-center open-label study to investigate the efficacy and safety of repeated subcutaneous injections of lanreotide Autogel in patients with acromegaly previously treated with octreotide.

OBJECTIVE: To evaluate the efficacy of lanreotide Autogel, a depot preparation of a long-acting somatostatin analogue, in patients with acromegaly who were previously treated with octreotide. METHODS: In a prospective single-center, open-label, comparative study, 13 patients were switched from octreotide treatment (baseline) to lanreotide Autogel therapy at a fixed dosage of 90 mg/4 wk. After 6 injections, the dosage was titrated to 60, 90, or 120 mg/4 wk, on the basis of growth hormone (GH) levels, for a further 6 injections. Mean GH and insulinlike growth factor-I (IGF-I) levels were determined at baseline, during treatment (to 48 weeks), and up to 8 weeks after the last injection. RESULTS: There was no significant change in the proportion of patients with GH and IGF-I control from baseline to week 48 (GH, 85% to 89%; IGF-I, 46% to 62%). Mean GH levels changed little from baseline, but mean IGF-I levels were significantly lower after 32 weeks (P<.05) and 48 weeks (P<.02). Data collected at 6 and 8 weeks after the last injection suggested that the efficacy of lanreotide Autogel can persist for longer than 4 weeks. CONCLUSION: This small study suggests that lanreotide Autogel is at least as effective as octreotide in the control of acromegaly and may last for longer than the recommended 4 weeks. It appears to be a useful alternative to long-acting octreotide in the treatment of acromegaly.

Evaluation of an enzyme immunoassay for plasma-free metanephrines in the diagnosis of catecholamine-secreting tumors.

OBJECTIVE: To define the test characteristics of an enzyme immunoassay (EIA) for plasma-free metanephrines (metanephrine and normetanephrine) in the diagnosis of pheochromocytoma and paraganglioma. DESIGN: Prospective observational design from a single University Hospital. Twenty-four hour urine for catecholamines and plasma for free metanephrines were collected from patients with a clinical suspicion of pheochromocytoma or paraganglioma. Patient records were reviewed for clinical data, follow-up, imaging and laboratory results to establish or exclude the diagnosis of pheochromocytoma. PATIENTS AND METHODS: Out of 178 consecutive patients, 10 had a paraganglioma and 12 had a pheochromocytoma: 156 were finally judged not to harbour active tumors and were therefore considered as controls. The main outcome measure was the diagnosis or exclusion of paraganglioma or pheochromocytoma and test characteristics of plasma-free metanephrines measured by EIA. RESULTS: Urinary epinephrine had a sensitivity of 45.5% and norepinephrine a sensitivity of 75% (98.8% specificity) for the diagnosis of pheochromocytoma. Plasma-free metanephrine and normetanephrine both had a sensitivity of 66.7% and a specificity of 100%, but when combined (either positive) they demonstrated a 91.7% sensitivity with a preserved specificity of 100%. For the diagnosis of paraganglioma, urinary norepinephrine gave slightly better results than plasma-free metanephrines, but combined testing was of no additional value. CONCLUSIONS: Plasma-free metanephrines measured by EIA have better diagnostic test characteristics than urinary catecholamines in the diagnosis of pheochromocytoma. The EIA offers a simple and effective measurement of plasma-free metanephrines.

The prevalence and characteristic features of cyclicity and variability in Cushing's disease.

OBJECTIVE: Cyclical Cushing's syndrome may render the diagnosis and management of Cushing's disease difficult. The aim of the present study was to investigate the prevalence of cyclicity and variability in patients with Cushing's disease, and to identify putative distinctive features. DESIGN: Retrospective case-note study. METHODS: We analysed the case records of 201 patients with Cushing's disease in a retrospective case-note study. Cyclicity was considered as the presence of at least one cycle, defined as a clinical and/or biochemical hypercortisolaemic peak followed by clinical and biochemical remission, followed by a new clinical and/or biochemical hypercortisolaemic peak. The fluctuations of mean serum cortisol levels, as assessed by a 5-point cortisol day curve, defined the variability. RESULTS: Thirty (14.9%; 26 females) patients had evidence of cyclicity/variability. 'Cycling' patients were older but no difference in sex or paediatric distribution was revealed between 'cycling' and 'non-cycling' patients. The median number of cycles was two for each patient, and 4 years was the median intercyclic period. A trend to lower cure rate post-neurosurgery and lower adenoma identification was observed in 'cycling' compared with 'non-cycling' patients. In multivariate analysis, older patients, longer follow-up, female sex and no histological identification of the adenoma were associated with an increased risk of cyclic disease. CONCLUSIONS: This large population study reveals that cyclicity/variability is not an infrequent phenomenon in patients with Cushing's disease, with a minimum prevalence of 15%. Physicians should be alert since it can lead to frequent problems in diagnosis and management, and no specific features can be used as markers.

Contrasting clinical manifestations of SDHB and VHL associated chromaffin tumours.

Mutations in succinate dehydrogense-B (SDHB) and the von Hippel-Lindau (VHL) genes result in an increased risk of developing chromaffin tumours via a common aetiological pathway. The aim of the present retrospective study was to compare the clinical phenotypes of disease in subjects developing chromaffin tumours as a result of SDHB mutations or VHL disease. Thirty-one subjects with chromaffin tumours were assessed; 16 subjects had SDHB gene mutations and 15 subjects had a diagnosis of VHL. VHL-related tumours were predominantly adrenal phaeochromocytomas (22/26; 84.6%), while SDHB-related tumours were predominantly extra-adrenal paragangliomas (19/25; 76%). Median age at onset of the first chromaffin tumour was similar in the two cohorts. Tumour size was significantly larger in the SDHB cohort in comparison with the VHL cohort (P=0.002). Multifocal disease was present in 9/15 (60%) of the VHL cohort (bilateral phaeochromocytomas) and only 3/16 (19%) of the SDHB cohort, while metastatic disease was found in 5/16 (31%) of the SDHB cohort but not in the VHL cohort to date. The frequency of symptoms, hypertension and the magnitude of catecholamine secretion appeared to be greater in the SDHB cohort. Renal cell carcinomas were a feature in 5/15 (33%) of the VHL cohort and 1/16 (6%) of the SDHB cohort. These data indicate that SDHB-related tumours are predominantly extra-adrenal in location and associated with higher catecholamine secretion and more malignant disease, in subjects who appear more symptomatic. VHL-related tumours tend to be adrenal phaeochromocytomas, frequently bilateral and associated with a milder phenotype.

Clinical manifestations of familial paraganglioma and phaeochromocytomas in succinate dehydrogenase B (SDH-B) gene mutation carriers.

OBJECTIVE: Phaeochromocytomas and paragangliomas are familial in up to 25% of cases and can result from succinate dehydrogenase (SDH) gene mutations. The aim of this study was to describe the clinical manifestations of subjects with SDH-B gene mutations. DESIGN: Retrospective case-series. PATIENTS: Thirty-two subjects with SDH-B gene mutations followed up between 1975 and 2007. Mean follow-up of 5.8 years (SD 7.4, range 0-31). Patients seen at St Bartholomew's Hospital, London and other UK centres. MEASUREMENTS: Features of clinical presentation, genetic mutations, tumour location, catecholamine secretion, clinical course and management. RESULTS: Sixteen of 32 subjects (50%) were affected by disease. Two previously undescribed mutations in the SDH-B gene were noted. A family history of disease was apparent in only 18% of index subjects. Mean age at diagnosis was 34 years (SD 15.4, range 10-62). 50% of affected subjects had disease by the age of 26 years. 69% (11 of 16) were hypertensive and 80% (12 of 15) had elevated secretions of catecholamines/metabolites. 24% (6 of 25) of tumours were located in the adrenal and 76% (19 of 25) were extra-adrenal. 19% (3 of 16) had multifocal disease. Metastatic paragangliomas developed in 31% (5 of 16). One subject developed a metastatic type II papillary renal cell carcinoma. The cohort malignancy rate was 19% (6 of 32). Macrovascular disease was noted in two subjects without hypertension. CONCLUSION: SDH-B mutation carriers develop disease early and predominantly in extra-adrenal locations. Disease penetrance is incomplete. Metastatic disease is prominent but levels are less than previously reported. Clinical manifestations may include papillary renal cell carcinoma and macrovascular disease.

Pre-spliceosomal binding of U1 small nuclear ribonucleoprotein (RNP) and heterogenous nuclear RNP E1 is associated with suppression of a growth hormone receptor pseudoexon.

Pseudoexons occur frequently in the human genome. This paper characterizes a pseudoexon in the GH receptor gene. Inappropriate activation of this pseudoexon causes Laron syndrome. Using in vitro splicing assays, pseudoexon silencing was shown to require a combination of a weak 5' pseudosplice-site and splicing silencing elements within the pseudoexon. Immunoprecipitation experiments showed that specific binding of heterogenous nuclear ribonucleoprotein E1 (hnRNP E1) and U1 small nuclear ribonucleoprotein (snRNP) in the pre-spliceosomal complex was associated with silencing of pseudoexon splicing. The possible role of hnRNP E1 was further supported by RNA interference experiments in cultured cells. Immunoprecipitation experiments with three other pseudoexons suggested that pre-spliceosomal binding of U1 snRNP is a potential general mechanism of suppression of pseudoexons.

Unmasking of central hypothyroidism following growth hormone replacement in adult hypopituitary patients.

BACKGROUND: The effect of GH replacement on thyroid function in hypopituitary patients has hitherto been studied in small groups of children and adults with conflicting results. OBJECTIVE: We aimed to define the effect and clinical significance of adult GH replacement on thyroid status in a large cohort of GH-deficient patients. PATIENTS AND METHOD: We studied 243 patients with severe GH deficiency due to various hypothalamo-pituitary disorders. Before GH treatment, 159 patients had treated central hypothyroidism (treated group) while 84 patients were considered euthyroid (untreated group). GH dose was titrated over 3 months to achieve serum IGF-1 concentration in the upper half of the age-adjusted normal range. Serial measurements of serum T4, T3, TSH and quality of life were made at baseline and at 3 and 6 months after commencing GH replacement. RESULTS: In the untreated group, we observed a significant reduction in serum T4 concentration without a significant increase in serum T3 or TSH concentration; 30/84 patients (36%) became hypothyroid and needed initiation of T4 therapy. Similar but lesser changes were seen in the treated group, 25 of whom (16%) required an increase in T4 dose. Patients who became hypothyroid after GH replacement had lower baseline serum T4 concentration, were more likely to have multiple pituitary hormone deficiencies and showed less improvement in quality of life compared with patients who remained euthyroid. CONCLUSION: GH deficiency masks central hypothyroidism in a significant proportion of hypopituitary patients and this is exposed after GH replacement. We recommend that hypopituitary patients with GH deficiency and low normal serum T4 concentration should be considered for T4 replacement prior to commencement of GH in order to provide a robust baseline from which to judge the clinical effects of GH replacement.