Timo Sane

Molecular diagnosis of pituitary adenoma predisposition caused by aryl hydrocarbon receptor-interacting protein gene mutations

Pituitary adenomas are common neoplasms of the anterior pituitary gland. Germ-line mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene cause pituitary adenoma predisposition (PAP), a recent discovery based on genetic studies in Northern Finland. In this population, a founder mutation explained a significant proportion of all acromegaly cases. Typically, PAP patients were of a young age at diagnosis but did not display a strong family history of pituitary adenomas. To evaluate the role of AIP in pituitary adenoma susceptibility in other populations and to gain insight into patient selection for molecular screening of the condition, we investigated the possible contribution of AIP mutations in pituitary tumorigenesis in patients from Europe and the United States. A total of 460 patients were investigated by AIP sequencing: young acromegaly patients, unselected acromegaly patients, unselected pituitary adenoma patients, and endocrine neoplasia-predisposition patients who were negative for MEN1 mutations. Nine AIP mutations were identified. Because many of the patients displayed no family history of pituitary adenomas, detection of the condition appears challenging. Feasibility of AIP immunohistochemistry (IHC) as a prescreening tool was tested in 50 adenomas: 12 AIP mutation-positive versus 38 mutation-negative pituitary tumors. AIP IHC staining levels proved to be a useful predictor of AIP status, with 75% sensitivity and 95% specificity for germ-line mutations. AIP contributes to PAP in all studied populations. AIP IHC, followed by genetic counseling and possible AIP mutation analysis in IHC-negative cases, a procedure similar to the diagnostics of the Lynch syndrome, appears feasible in identification of PAP.

Large Genomic Deletions in AIP in Pituitary Adenoma Predisposition

CONTEXTnGermline mutations in AIP have been recently shown to cause pituitary adenoma predisposition (PAP). Subsequently, many intragenic germline mutations have been reported, both in familial and in sporadic settings.nnnOBJECTIVEnOur objective was to evaluate the possible contribution of large genomic germline AIP deletions, an important mutation type in tumor predisposition syndromes, in PAP.nnnDESIGNnHere, we applied the multiplex ligation-dependent probe amplification assay to examine whether large genomic AIP or MEN1 alterations account for a subset of PAP cases.nnnPATIENTSnThe study was performed on familial and sporadic pituitary adenoma cases of European origin, which had previously tested negative for germline AIP and MEN1 mutations by sequencing.nnnRESULTSnTwo of 21 pituitary adenoma families (9.5%) were found to harbor an AIP deletion. No copy number changes were detected among 67 sporadic pituitary adenoma patients. No MEN1 deletions were found.nnnCONCLUSIONSnThe present study shows that large genomic AIP deletions account for a subset of PAP. Therefore, in suspected PAP cases undergoing counseling and AIP genetic testing, multiplex ligation-dependent probe amplification could be considered if direct sequencing does not identify a mutation.

The expression of AIP-related molecules in elucidation of cellular pathways in pituitary adenomas.

Germline mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene predispose to the development of pituitary adenomas. Here, we characterized AIP mutation positive (AIPmut+) and AIP mutation negative (AIPmut-) pituitary adenomas by immunohistochemistry. The expressions of the AIP-related proteins aryl hydrocarbon receptor (AHR), AHR nuclear translocator (ARNT), cyclin-dependent kinase inhibitor 1B encoding p27(Kip1), and hypoxia-inducible factor 1-alpha were examined in 14 AIPmut+ and 53 AIPmut- pituitary adenomas to detect possible expression differences. In addition, the expression of CD34, an endothelial and hematopoietic stem cell marker, was analyzed. We found ARNT to be less frequently expressed in AIPmut+ pituitary adenomas (P = 0.001), suggesting that AIP regulates the ARNT levels. AIP small interfering RNA-treated HeLa, HEK293, or Aip-null mouse embryonic fibroblast cells did not show lowered expression of ARNT. Instead, in the pituitary adenoma cell line GH3, Aip silencing caused a partial reduction of Arnt and a clear increase in cell proliferation. We also observed a trend for increased expression of nuclear AHR in AIPmut+ samples, although the difference was not statistically significant (P = 0.06). The expressions of p27(Kip1), hypoxia-inducible factor 1-alpha, or CD34 did not differ between tumor types. The present study shows that the expression of ARNT protein is significantly reduced in AIPmut+ tumors. We suggest that the down-regulation of ARNT may be connected to an imbalance in AHR/ARNT complex formation arising from aberrant cAMP signaling.

Reversible congenital hypogonadotropic hypogonadism in patients with CHD7, FGFR1 or GNRHR mutations.

Background Congenital hypogonadotropic hypogonadism (HH) is a rare cause for delayed or absent puberty. These patients may recover from HH spontaneously in adulthood. To date, it is not possible to predict who will undergo HH reversal later in life. Herein we investigated whether Finnish patients with reversal of congenital hypogonadotropic hypogonadism (HH) have common phenotypic or genotypic features. Methods and Findings Thirty-two male HH patients with anosmia/hyposmia (Kallmann Syndrome, KS; nu200a=u200a26) or normal sense of smell (nHH; nu200a=u200a6) were enrolled (age range, 18–61 yrs). The patients were clinically examined, and reversal of HH was assessed after treatment withdrawal. KAL1, FGFR1, FGF8, PROK2, PROKR2, CHD7, WDR11, GNRHR, GNRH1, KISS1R, KISS1, TAC3, TACR3, and LHβ were screened for mutations. Six HH patients (2 KS, 4 nHH) were verified to have reversal of HH. In the majority of cases, reversal occurred early in adulthood (median age, 23 yrs; range, 21–39 yrs). All had spontaneous testicular growth while on testosterone replacement therapy (TRT). One nHH subject was restarted on TRT due to a decline in serum T. Two reversal variants had a same GNRHR mutation (R262Q), which was accompanied by another GNRHR mutation (R139H or del309F). In addition, both of the KS patients had a mutation in CHD7 (p.Q51X) or FGFR1 (c.91+2T>A). Conclusions Considerable proportion of patients with HH (8% of KS probands) may recover in early adulthood. Spontaneous testicular enlargement during TRT was highly suggestive for reversal of HH. Those with the GNRHR mutation R262Q accompanied by another GNRHR mutation may be prone to reversal, although even patients with a truncating mutation in CHD7 or a splice-site mutation in FGFR1 can recover. We recommend that all adolescents and young adults with congenital HH should be informed on the possibility of reversal.

Gain of chromosome 3 and loss of 13q are frequent alterations in pituitary adenomas.

Genetic changes underlying the tumorigenesis of pituitary adenomas (PA) are poorly characterized. To search for characteristic genomic imbalances involved in PA, we examined 38 cases: 12 hormone-secreting (HS) and 26 non-functioning (NF) PA, by comparative genomic hybridization. The most frequent DNA copy number change in both kinds of tumors was loss of 13q. Gains of chromosomes 3, 7 and 14, 6p, and 20q were more frequent in HSPA than in NFPA. These data indicate that the 13q region may harbor tumor suppressor genes determining the tumorigenesis of PA and gain in chromosome 3 may be related to hormone secretion. These findings provide a basis to search for candidate diagnostic markers of HSPA.

Analytical and preanalytical validation of a new mass spectrometric serum 5-hydroxyindoleacetic acid assay as neuroendocrine tumor marker

BACKGROUNDnSerum 5-hydroxyindoleacetic acid (5-HIAA) could replace the determination of 24-h urinary 5-HIAA for diagnosis and follow-up of neuroendocrine tumors (NETs). We developed and validated a straightforward liquid chromatography tandem mass spectrometry (LC-MS/MS) assay for serum 5-HIAA.nnnMETHODSnWe used serum samples from healthy volunteers (n=136) and patients suspected or followed for NET (n=129). Samples were spiked with 5-HIAA-D2, extracted and quantified by LC-MS/MS. We studied the effects of sample storage, sample device, a meal and diurnal variation on serum 5-HIAA. Furthermore, we established a reference range for serum 5-HIAA and compared our assay with a urinary 5-HIAA HPLC assay and a commercial plasma chromogranin A (CgA) immunoassay.nnnRESULTSnOur LC-MS/MS assay is sensitive (LOQ 5 nmol/L), has a wide assay range (5-10,000 nmol/L) and short analysis time (7 min). 5-HIAA in serum is stable for several days in various temperatures and during five freeze-thaw cycles. We found no diurnal variation (p ≥ 0.20) and a meal had no effect on serum 5-HIAA (p=0.89). We suggest an upper reference limit of 123 nmol/L for serum 5-HIAA. The area under curve (AUC) in receiver operator characteristics (ROC) analysis was 0.83 for urinary 5-HIAA, 0.81 for serum 5-HIAA and 0.76 for CgA, respectively.nnnCONCLUSIONSnThe LC-MS/MS assay for serum 5-HIAA discriminates between healthy individuals and patients with NET and is well suited for the diagnosis and follow-up of NETs.

Severe hypoglycaemia in drug-treated diabetic patients needs attention: A population-based study

Abstract Objective. To study one-year incidence and risk factors of severe hypoglycaemias (SH) in adult drug-treated diabetic patients living in two Finnish communities. Design. The episodes of SH and their risk factors were identified from local ambulance registers, from the databases of local health care units, and from patient questionnaires. Setting. The target population consisted of all drug-treated diabetic patients from the two middle-sized communities in southern Finland, altogether 1776 patients. The study was retrospective. Subjects. A total of 1469 patients (82.7% of the target population) gave informed consent for the use of their medical records and 1325 patients (74.6% of the target population) returned the detailed 36-item questionnaire. Results. Of type 1 and type 2 insulin-treated diabetic patients, 14.6% and 1.0%, respectively, needed ambulance or emergency room care (incidence of 30.5 and 3.0 per 100 patient years). However, 31.0% of type 1 and 12.3% of type 2 diabetic patients reported at least one episode of SH (incidence of 72.0 and 27.0 per 100 patient years). Of all insulin-treated patients, 53 (7.8%) reported three or more episodes of SH. Significant independent risk factors for SH were depression, daily exercise, and nephropathy but not glycaemic control. Conclusion. The incidence of SH was high in both types of insulin-treated diabetic patients. However, the recurrent episodes of SH were clustered in a small minority of insulin-treated patients with diabetes. The risk of SH should be considered when assessing the treatment target for an individual diabetic patient.

Helsinki score—a novel model for prediction of metastases in adrenocortical carcinomas

Histopathologic diagnosis of adrenocortical tumors is based on adverse features that indicate malignant potential. Proliferation index has served as a supplemental tool in assessing the malignant potential of adrenocortical tumors. None of the current histologic classification systems can sufficiently accurately predict tumors metastatic potential. We studied 177 consecutive adult patients with primary adrenocortical tumors operated on at Helsinki University Central Hospital between 1990 and 2003, all patients with a minimum follow-up of 5 years. We determined for each tumor the Weiss score and the Weiss revisited score by Aubert. Proliferation index was measured by computer-assisted image analysis. Each of the 9 Weiss criteria and the proliferation index were then used to establish a scoring system to predict the metastatic potential of adrenocortical tumors. Use of stepwise regression analysis led us to propose a calculation: 3 × mitotic rate (>5/50 high-power fields) + 5 × presence of necrosis + proliferation index in the most proliferative area of the tumor. Using a cutoff value of 8.5, the new scoring system was able to diagnose metastatic adrenocortical carcinoma with 100% sensitivity (confidence interval [CI], 76.8%-100%) and 99.4% specificity (CI, 96.6%-100%). The corresponding sensitivity of the Weiss system was 100% (CI, 76.8%-100%), and specificity, 90.2% (CI, 84.6%-94.3%), with sensitivity of the Weiss revisited system at 100% (CI, 76.8%-100%) and specificity at 96.9% (CI, 93.0%-99.0%). The new Helsinki score thus was accurate in predicting the metastatic potential of adrenocortical tumors.

Is Biochemical Screening for Pheochromocytoma in Adrenal Incidentalomas Expressing Low Unenhanced Attenuation on Computed Tomography Necessary

OBJECTIVEnPheochromocytomas are characterized by a high attenuation value on unenhanced computed tomography (CT). It is not known whether pheochromocytoma could be ruled out as a cause of adrenal incidentalomas on the basis of unenhanced attenuation values only.nnnDESIGNnWe retrospectively evaluated the outcome of routine biochemical screening for pheochromocytoma in a series of adrenal incidentalomas in relationship to the unenhanced attenuation values on CT.nnnMETHODSnAn unenhanced CT was available in 174 of 184 patients with 214 adrenal incidentalomas. All patients were screened for pheochromocytoma with 24-h urinary metanephrines and normetanephrines and for hypercortisolism (1 mg dexamethasone test and ACTH). Hypertensive patients were screened for aldosterone overproduction (aldosterone to renin ratio and 24 h urinary aldosterone). The results were compared between incidentalomas with high [≥10 Hounsfield units (HU)] and low (<10 HU) unenhanced attenuation values.nnnRESULTSnOne hundred forty-six incidentalomas in 115 patients had an unenhanced HU less than 10. None of these patients had elevated 24-h fractionated urinary metanephrines or normetanephrines suggesting pheochromocytoma. Sixty-eight incidentalomas in 59 patients had an unenhanced HU of 10 or greater, and nine (15.2%) of these patients had surgically and histologically verified pheochromocytoma. Incidentalomas with a HU of 10 or greater were significantly larger (2.6 ± 1.5 vs. 2.3 ± 1.2 cm; P < 0.001), more often functional (27.9 vs. 8.9%, P < 0.001), and more often operated (44.1 vs. 10.2%; P < 0.001) than those with a Hounsfield unit less than 10.nnnCONCLUSIONnThe results of this study indicate that routine biochemical screening of pheochromocytoma in small homogenous adrenal incidentalomas characterized by an unenhanced Hounsfield unit value less than 10 HU may not be necessary.

A comparative study of two various models of organising diabetes follow-up in public primary health care – the model influences the use of services, their quality and costs

BackgroundIn Finland diabetologists have long been concerned about the level of diabetes care as the incidence of type 1 diabetes and complicated type 2 diabetes is exceeding the capacity of specialist clinics. We compared the outcome of diabetes care in two middle-sized Finnish municipalities with different models of diabetes care organisation in public primary health care. In Kouvola the primary health care of all diabetic patients is based on general practitioners, whereas in Nurmijärvi the follow-up of type 1 and most complicated type 2 diabetic patients is assigned to a general practitioner specialised in diabetes care.MethodsOur study population consisted of all adult diabetic patients living in the municipalities under review.We compared the use and costs of public diabetes care, glycemic control, blood pressure, LDL-cholesterol level, the application of the national guidelines and patient satisfaction. The main outcome measures were the costs and use of health care services due to diabetes and its complications.ResultsIn Nurmijärvi, where diabetes care was centralised, more type 1 diabetic patients were followed up in primary health care than in Kouvola, where general practitioners need more specialist consultations. The centralisation resulted in cost savings in the diabetes care of type 1 diabetic patients. Although the quality of care was similar, type 1 diabetic patients were more satisfied with their follow-up in the centralised system. In the care of type 2 diabetic patients the centralised system required fewer specialist consultations, but the quality and costs were similar in both models.ConclusionsThe follow-up of most diabetic patients – including type 1 diabetes – can be organised in primary health care with the same quality as in secondary care units. The centralised primary care of type 1 diabetes is less costly and requires fewer specialist consultations.