Variability in distribution and use of tuberculosis diagnostic tests in Kenya: a cross-sectional survey.

BACKGROUND: Globally, 40% of all tuberculosis (TB) cases, 65% paediatric cases and 75% multi-drug resistant TB (MDR-TB) cases are missed due to underreporting and/or under diagnosis. A recent Kenyan TB prevalence survey found that a significant number of TB cases are being missed here. Understanding spatial distribution and patterns of use of TB diagnostic tests as per the guidelines could potentially help improve TB case detection by identifying diagnostic gaps. METHODS: We used 2015 Kenya National TB programme data to map TB case notification rates (CNR) in different counties, linked with their capacity to perform diagnostic tests (chest x-rays, smear microscopy, Xpert MTB/RIF®, culture and line probe assay). We then ran hierarchical regression models for adults and children to specifically establish determinants of use of Xpert® (as per Kenyan guidelines) with county and facility as random effects. RESULTS: In 2015, 82,313 TB cases were notified and 7.8% were children. The median CNR/100,000 amongst 0-14yr olds was 37.2 (IQR 20.6, 41.0) and 267.4 (IQR 202.6, 338.1) for ≥15yr olds respectively. 4.8% of child TB cases and 12.2% of adult TB cases had an Xpert® test done, with gaps in guideline adherence. There were 2,072 microscopy sites (mean microscopy density 4.46/100,000); 129 Xpert® sites (mean 0.31/100,000); two TB culture laboratories and 304 chest X-ray facilities (mean 0.74/100,000) with variability in spatial distribution across the 47 counties. Retreatment cases (i.e. failures, relapses/recurrences, defaulters) had the highest odds of getting an Xpert® test compared to new/transfer-in patients (AOR 7.81, 95% CI 7.33-8.33). Children had reduced odds of getting an Xpert® (AOR 0.41, CI 0.36-0.47). HIV-positive individuals had nearly twice the odds of getting an Xpert® test (AOR 1.82, CI 1.73-1.92). Private sector and higher-level hospitals had a tendency towards lower odds of use of Xpert®. CONCLUSIONS: We noted under-use and gaps in guideline adherence for Xpert® especially in children. The under-use despite considerable investment undermines cost-effectiveness of Xpert®. Further research is needed to develop strategies enhancing use of diagnostics, including innovations to improve access (e.g. specimen referral) and overcoming local barriers to adoption of guidelines and technologies.

The potential of a multiplex high-throughput molecular assay for early detection of first and second line tuberculosis drug resistance mutations to improve infection control and reduce costs: a decision analytical modeling study.

BACKGROUND: Molecular resistance detection (MRD) of resistance to second-line anti-tuberculous drugs provides faster results than phenotypic tests, may shorten treatment and allow earlier separation among patients with and without second-line drug resistance. METHODS: In a decision-analytical model we simulated a cohort of patients diagnosed with TB in a setting where drug resistant TB is highly prevalent and requires initial hospitalization, to explore the potential benefits of a high-throughput MRD-assay for reducing potential nosocomial transmission of highly resistant strains, and total costs for diagnosis of drug resistance, treatment and hospitalization. In the base case scenario first-line drug resistance was diagnosed with WHO-endorsed molecular tests, and second-line drug resistance with culture and phenotypic methods. Three alternative scenarios were explored, each deploying high-throughput MRD allowing either detection of second-line mutations in cultured isolates, directly on sputum, or MRD with optimized markers. RESULTS: Compared to a base case scenario, deployment of high-throughput MRD reduced total costs by 17-21 %. The period during which nosocomial transmission may take place increased by 15 % compared to the base case if MRD had currently reported suboptimal sensitivity and required cultured isolates; increased by 7 % if direct sputum analysis were possible including in patients with smear-negative TB, and reduced by 24 % if the assay had improved markers, but was still performed on cultured isolates. Improved clinical sensitivity of the assay (additional markers) by more than 35 % would be needed to avoid compromising infection control. CONCLUSIONS: Further development of rapid second-line resistance testing should prioritize investment in optimizing markers above investments in a platform for direct analysis of sputum.

HRPT2, encoding parafibromin, is mutated in hyperparathyroidism-jaw tumor syndrome.

We report here the identification of a gene associated with the hyperparathyroidism-jaw tumor (HPT-JT) syndrome. A single locus associated with HPT-JT (HRPT2) was previously mapped to chromosomal region 1q25-q32. We refined this region to a critical interval of 12 cM by genotyping in 26 affected kindreds. Using a positional candidate approach, we identified thirteen different heterozygous, germline, inactivating mutations in a single gene in fourteen families with HPT-JT. The proposed role of HRPT2 as a tumor suppressor was supported by mutation screening in 48 parathyroid adenomas with cystic features, which identified three somatic inactivating mutations, all located in exon 1. None of these mutations were detected in normal controls, and all were predicted to cause deficient or impaired protein function. HRPT2 is a ubiquitously expressed, evolutionarily conserved gene encoding a predicted protein of 531 amino acids, for which we propose the name parafibromin. Our findings suggest that HRPT2 is a tumor-suppressor gene, the inactivation of which is directly involved in predisposition to HPT-JT and in development of some sporadic parathyroid tumors.

Increased ratio of mRNA expression of the genes CYP17 and CYP11B1 indicates autonomous cortisol production in adrenocortical tumors.

OBJECTIVE: Due to increased use of imaging techniques, adrenal incidentalomas are frequently detected. The majority are non-hyperfunctioning adrenocortical tumors. We have previously shown that expression of the gene CYP17, coding for the enzyme in the cortisol pathway, correlates with cortisol release from adrenocortical tumors in vitro. The aim of this study was to compare clinical data with mRNA expression of CYP17 and CYP11B1 in adrenocortical tumors from patients with and without Cushing's syndrome and to identify adrenal tumors that may cause subclinical Cushing's syndrome. DESIGN: A retrospective study of 34 patients undergoing adrenalectomy due to an adrenal tumor. METHODS: Clinical data were collected. In the adrenal gland the mRNA expression of the genes CYP17 and CYP11B1 was studied with in situ hybridisation technique. RESULTS: The median ratio of CYP17/CYP11B1 expression in tumors from patients with Cushing's syndrome was significantly higher than the median ratio in the non-hyperfunctioning tumors. Tumors from 2 patients with subclinical Cushing's syndrome had ratios within the upper range for non-hyperfunctioning tumors. CONCLUSIONS: The ratio between the expression of the genes CYP17 and CYP11B1 in tumors from patients with Cushing's syndrome is significantly higher than in the non-hyperfunctioning tumors. This indicates that 17alpha-hydroxylase is a major determinant of cortisol overproduction. The patients with subclinical Cushing's syndrome in this study are too few to draw any firm conclusions although the results suggest that subclinical Cushing's syndrome may be identified post-operatively with this method.

Methylation of the p16INK4A promoter is associated with malignant behavior in abdominal extra-adrenal paragangliomas but not pheochromocytomas.

Pheochromocytomas and abdominal extra-adrenal paragangliomas are related to endocrine tumors of the sympathetic nervous system. Studies in animal models have shown that inactivation of the products of the cyclin dependent kinase inhibitor 2A (CDKN2A) gene locus, p16INK4A and p14ARF, promotes the development of pheochromocytoma, especially in malignant form. The present study evaluated the involvement of CDKN2A in human pheochromocytomas and abdominal extra-adrenal paragangliomas from 55 patients. Promoter methylation was assessed using quantitative Pyrosequencing and methylation-specific PCR, and mRNA expression was measured by quantitative real-time PCR. For p16, western blot analysis and sequencing were also performed. succinate dehydrogenase complex subunit B (SDHB) sequencing analysis included extra-adrenal paragangliomas, all tumors classified as malignant, and cases diagnosed at 30 years or younger. The p16INK4A promoter was heavily methylated in a subset of paragangliomas, and this was significantly associated with malignancy (P<0.0043) and SDHB mutation (P<0.002). p16INK4A mRNA expression showed moderate suppression in malignant cases (P<0.05). In contrast, very little p14ARF promoter methylation was seen and there was no significant difference in p14ARF expression between tumors and normal samples. The p16 protein expression was reduced in 16 tumors, and sequence variations were observed in four tumors including the missense mutation A57V and the single nucleotide polymorphism (SNP) A148T. The results suggest that p16INK4A, and not p14ARF, is a subject of frequent involvement in these tumors. Importantly, hypermethylation of the p16INK4A promoter was significantly associated with malignancy and metastasis, and SDHB gene mutations. This finding suggests an etiological link and could provide a clinical utility for diagnostic purposes.

Evaluation of TB and HIV services prior to introducing TB-HIV activities in two rural districts in western Kenya.

SETTING: Health facilities providing tuberculosis (TB) treatment in two districts in rural western Kenya with a high TB and human immunodeficiency virus (HIV) burden. OBJECTIVE: To evaluate TB and HIV/acquired immune-deficiency syndrome (AIDS) services at the facilities and identify barriers to providing quality diagnostic HIV testing and counseling (DTC) and HIV treatment for TB patients in anticipation of the introduction of TB-HIV collaborative services. METHODS: We performed a standard interview with health workers responsible for TB care, inspected the facilities and collected service delivery data. A self-administered questionnaire on training attended was given to all health workers. Results were shared with stakeholders and plans for implementation were developed. RESULTS: Of the 59 facilities, 58 (98%) provided TB treatment, 19 (32%) offered sputum microscopy and 24 (41%) HIV testing. Most facilities (72%) advised HIV testing only if TB patients were suspected of having AIDS. Barriers identified included unaccommodating TB clinic schedules and lack of space, which was an obstacle to holding confidential discussions. The need to refer for HIV testing and/or HIV care was a perceived barrier to recommending these services. Activities implemented following the assessment aimed 1) to provide HIV testing and cotrimoxazole prophylaxis at all TB treatment clinics, 2) to increase availability of HIV treatment services, and 3) to address structural needs at each facility. CONCLUSION: This evaluation identified barriers to the implementation of HIV testing and care services within facilities providing TB treatment.

Parafibromin immunoreactivity: its use as an additional diagnostic marker for parathyroid tumor classification.

Parafibromin is a protein product derived from the hyperparathyroidism 2(HRPT2) tumor suppressor geneand its inactivation has been coupled to familial and sporadic forms of parathyroid malignancy. In this study, we have conducted immunohistochemistry on 33 parathyroid carcinomas (22 unequivocal and 11 equivocal) using four parafibromin antibodies directed to different parts of the protein. Furthermore, for a fraction of cases, the immunohistochemical results were compared with known HRPT2 mutational status. Our findings show that 68% (15 out of 22) of the unequivocal carcinomas exhibited reduced expression of parafibromin while the 25 sporadic adenomas used as controls were entirely positive for parafibromin expression. Additionally, three out of the six carcinomas with known HRPT2 mutations showed reduced expression of parafibromin. Using all four antibodies, comparable results were obtained on the cellular level in individual tumors suggesting that there exists no epitope of choice in parafibromin immunohistochemistry. The results agree with the demonstration of a approximately 60 kDa product preferentially in the nuclear fraction by western blot analysis. We conclude that parafibromin immunohistochemistry could be used as an additional marker for parathyroid tumor classification, where positive samples have low risk of malignancy, whereas samples with reduced expression could be either carcinomas or rare cases of adenomas likely carrying an HRPT2 mutation.

Lymphocytic hypophysitis: report of two biopsy-proven cases and one suspected case with pituitary autoantibodies.

Lymphocytic hypophysitis (LyH) is a rare inflammatory disease, considered to be autoimmune. LyH has mainly been reported in females and in relation to pregnancy or the post-partum period. We describe a 73-yr-old woman and a 63-yr-old male who were evaluated at our clinic because of pituitary hormone deficits. Both patients had pituitary masses suggestive of a pituitary adenoma on magnetic resonance imaging (MRI). Transsphenoidal pituitary surgery was performed and histopathological examinations revealed LyH in both cases. Clinical, laboratory, radiological and the histopathological findings in these two patients are discussed in detail. In addition, we report on a 79-yr-old man with partial hypopituitarism and empty sella. Screening of a human pituitary cDNA library with his serum revealed autoantibodies against secretogranin II. This is a protein commonly present in human gonadotrophs, thyreotrophs and corticotrophs. Since the patient selectively showed the corresponding pituitary insufficiencies, we speculate on an autoimmune background. Further studies may ascertain the importance of secretogranin II autoantibodies as markers for LyH.

Accuracy of giant African pouched rats for diagnosing tuberculosis: comparison with culture and Xpert® MTB/RIF.

SETTING: Enhanced tuberculosis (TB) case finding using detection rats in Tanzania. OBJECTIVES: To assess the diagnostic accuracy of detection rats compared with culture and Xpert® MTB/RIF, and to compare enhanced case-finding algorithms using rats in smear-negative presumptive TB patients. DESIGN: A fully paired diagnostic accuracy study in which sputum of new adult presumptive TB patients in Tanzania was tested using smear microscopy, 11 detection rats, culture and Xpert. RESULTS: Of 771 eligible participants, 345 (45%) were culture-positive for Mycobacterium tuberculosis, and 264 (34%) were human immunodeficiency virus (HIV) positive. The sensitivity of the detection rats was up to 75.1% (95%CI 70.1-79.5) when compared with culture, and up to 81.8% (95%CI 76.0-86.5) when compared with Xpert, which was statistically significantly higher than the sensitivity of smear microscopy. Corresponding specificity was 40.6% (95%CI 35.9-45.5) compared with culture. The accuracy of rat detection was independent of HIV status. Using rats for triage, followed by Xpert, would result in a statistically higher yield than rats followed by light-emitting diode fluorescence microscopy, whereas the number of false-positives would be significantly lower than when using Xpert alone. CONCLUSION: Although detection rats did not meet the accuracy criteria as standalone diagnostic or triage testing for presumptive TB, they have additive value as a triage test for enhanced case finding among smear-negative TB patients if more advanced diagnostics are not available.

Bottom-up or top-down: unit cost estimation of tuberculosis diagnostic tests in India.

SETTING: Of 18 sites that participated in an implementation study of the Xpert® MTB/RIF assay in India, we selected five microscopy centres and two reference laboratories. OBJECTIVE: To obtain unit costs of diagnostic tests for tuberculosis (TB) and drug-resistant TB. DESIGN: Laboratories were purposely selected to capture regional variations and different laboratory types. Both bottom-up and the top-down methods were used to estimate unit costs. RESULTS: At the microscopy centres, mean bottom-up unit costs were respectively US$0.83 (range US$0.60-US$1.10) and US$12.29 (US$11.61-US$12.89) for sputum smear microscopy and Xpert. At the reference laboratories, mean unit costs were US$1.69 for the decontamination procedure, US$9.83 for a solid culture, US$11.06 for a liquid culture, US$29.88 for a drug susceptibility test, and US$18.18 for a line-probe assay. Top-down mean unit cost estimates were higher for all tests, and for sputum smear microscopy and Xpert these increased to respectively US$1.51 and US$13.58. The difference between bottom-up and top-down estimates was greatest for tests performed at the reference laboratories. CONCLUSION: These unit costs for TB diagnostics can be used to estimate resource requirements and cost-effectiveness in India, taking into account geographical location, laboratory type and capacity utilisation.

Loss of parafibromin expression in a subset of parathyroid adenomas.

Inactivation of the hyperparathyroidism-jaw tumour syndrome (HPT- JT) gene, HRPT2, was recently established as a genetic mechanism in the development of parathyroid tumours. Its encoded protein parafibromin has tumour-suppressor properties that play an important role in tumour development in the parathyroids, jaws and kidneys. Inactivating HRPT2 mutations are common in HPT- JT and parathyroid carcinomas, and have been described in a few cases of parathyroid adenomas with cystic features. In this study, 46 cases of cystic parathyroid adenomas previously investigated for HRPT2 mutations were characterized with regard to MEN1 gene mutations, cyclin D1 expression and parafibromin expression. In normal tissues and cell lines, parafibromin was ubiquitously expressed. Furthermore, parafibromin was detected as a dominating nuclear and a weaker cytoplasmic signal in transfected cell lines. In the three parathyroid tumours with inactivating HRPT2 mutations parafibromin expression was not detectable, and in one of two cases with aberrantly sized parafibromin the protein was delocalized. Both high and low cyclin D1 levels were found among HRPT2-mutated and -unmutated tumours, suggesting that these events are not mutually exclusive in parathyroid tumour development. The presented data suggest that in the majority of benign parathyroid tumours the expression of parafibromin remains unaltered, while the loss of parafibromin expression is strongly indicative of gene inactivation through mutation of the HRPT2 gene.

Genetic aberrations in adrenocortical tumors detected using comparative genomic hybridization correlate with tumor size and malignancy.

The differentiation between malignant and benign adrenocortical tumors is often difficult, and better markers are required. Because the genetic background of adrenocortical tumors is poorly characterized, we used comparative genomic hybridization (CGH) to screen for DNA sequence copy number changes in 8 sporadic primary adrenocortical cancers and 14 adenomas. There was a strong relationship between the number of genetic aberrations detected using CGH and both tumor size and malignancy. No alterations were seen in the smaller adenomas (< 5 cm), whereas the two largest adenomas (5 cm each) and seven of the eight cancers (7-20 cm) showed an increased number of genetic alterations. The presence of genetic aberrations detected using CGH was associated with an aneuploid DNA pattern. In the cancers, losses most often involved the chromosomal regions 2, 11q, and 17p (four of eight tumors), whereas gains took place at chromosomes 4 and 5 (four of eight tumors). In conclusion, our data indicate that genetic changes may help to define the malignant potential of adrenocortical tumors. Furthermore, the CGH results implicate several chromosomal regions that may contain genes with an important role in the development of adrenocortical cancers.

Lack of mutations in the TSHr and Gsalpha genes in TSHr antibody negative Graves' disease.

The aim of this study was to investigate whether TSHr antibody negative Graves' disease is associated with somatic mutations in the TSHr or Gsalpha genes and whether histopathologically defined thyroid lesions, i.e., hyperfunctioning adenoma, non-functioning follicular adenomas, or nodules in toxic and non-toxic multinodular goiters are associated with such mutations. No mutations but three germ-line polymorphisms were found in patients with TSHr antibody negative Graves' disease. The three polymorphisms are expected to have no or only minor effects on the signaling properties, and is not associated with altered antigenecity imposed by such mutations. Two heterozygous somatic TSHr mutations were found in two hyperfunctioning adenomas and in two toxic multinodular goiters. The lack of TSHr and Gsalpha mutations in TSHr antibody negative Graves' disease patients indicates that such mutations are neither primary nor secondary events in this disease. The results also confirm that somatic gain-of-function TSHr mutations are present in hyperfunctioning follicular adenomas and goiters, but not in non-functioning thyroid lesions.

Intraductal serrated adenoma of the pancreas. A case report.

CASE REPORT: A 48-year-old male with known hypothyreosis consulted his physician for symptoms compatible with TIA (transient ischemic attacks). Computer tomography (CT) in December 2001 revealed an irregular, lobulated mass in the processus uncinatus of the pancreas head. A CT examination 14 months later revealed status quo. In July 2004, a new CT showed an increase in size of the expansive pancreatic mass. The patient was operated on in August 2004 with a preliminary diagnosis of incidentaloma of the pancreas. The pathological examination showed a 4 x 3.5 x 2.5 cm large tumour. Histology revealed an intraductal serrated adenoma. The epithelial fronds had sawtooth-like configurations. An area with early invasive carcinoma was found. The tumour had progressed slowly during the 2.7 years of surveillance. Serrated neoplasia in the duodenum may result in similar cases in the future.

Increased amounts of a high molecular weight insulin-like growth factor II (IGF-II) peptide and IGF-II messenger ribonucleic acid in pancreatic islets of diabetic Goto-Kakizaki rats.

Insulin-like growth factor II (IGF-II), a member of the insulin family, regulates cell growth and differentiation. The IGF-II gene is localized close to the insulin gene in man and rat. IGF-II peptide binds weakly to the insulin receptor and exerts insulin-like effects on the blood glucose level. We studied IGF-II in endocrine pancreas in an animal model of noninsulin-dependent diabetes mellitus, the Goto-Kakizaki (GK) rat. At the age of 2 months, these rats have structural islet changes, with fibrosis and irregular configuration, so-called starfish-shaped islets. Immunohistochemical investigation revealed IGF-II immunoreactivity in the beta-cells in both GK and control rats. Pancreatic extraction, followed by size separation using gel chromatography, disclosed a high mol wt form of IGF-II in all animals, and RIA measurements revealed a considerably larger amount of the IGF-II peptide in the 2-and 6-month-old GK rats than in the 1-month GK and control rats. In situ hybridization of 3-month-old GK rats showed increased IGF-II messenger RNA expression in the starfish-shaped islets of GK rats than in the islets with normal structure in both diabetic and control animals. The reason for the increased amount of IGF-II is unclear. As the animals are diabetic before the islet changes occur, it might be a compensatory effect in response to hyperglycemia, but could also be a cause of the islet fibrosis.

Normal structural dopamine type 2 receptor gene in prolactin-secreting and other pituitary tumors.

Dopamine, acting via its specific receptor (DRD2) in the anterior pituitary, tonically inhibits pituitary prolactin secretion and lactotroph proliferation. In addition, dopamine agonist therapy for pituitary prolactinomas results in reduction of prolactin secretion and tumor regression. These observations lead to the speculation that functional dopamine uncoupling may release lactotrophs from the inhibitory effects of dopamine and contribute to the development of prolactin (PRL)-secreting pituitary tumors. We hypothesized that such an uncoupling may occur by inactivating mutation(s) of the DRD2. To test our hypothesis, we examined 79 pituitary tumors, mostly prolactinomas and mixed GH/PRL-secreting, for mutations in the coding exons of the DRD2 gene. We used the polymerase chain reaction and analyzed the fragments for migration abnormalities on denaturing gradient gel electrophoresis, complemented by direct DNA sequencing. No mutations were demonstrated, and all migration abnormalities detected by denaturing gradient gel electrophoresis were due to polymorphisms within the DRD2 gene. In addition, allelic losses in the multiple endocrine neoplasia type 1 region in 11q13 could not be demonstrated in all five informative prolactinomas. We conclude that mutations in the DRD2 gene do not occur in PRL or GH/PRL-secreting pituitary tumors and that allelic loss of 11q13 is uncommon in prolactinomas.

Genotyping of adrenocortical tumors: very frequent deletions of the MEN1 locus in 11q13 and of a 1-centimorgan region in 2p16.

To identify chromosomal regions that may contain loci for tumor suppressor genes involved in adrenocortical tumor development, a panel of 60 tumors (39 carcinomas and 21 adenomas) were screened for loss of heterozygosity. Although the vast majority of loss of heterozygosity (LOH) were detected in the carcinomas and involved chromosomes 2, 4, 11, and 18, only few were found in the adenomas. Therefore, 2 loci that harbor the familial cancer syndromes Carney complex in 2p16 and the multiple endocrine neoplasia type 1 gene in 11q13 were further studied in 27 (13 carcinomas and 14 adenomas) of the 60 tumors. Detailed analysis of the 2p16 region mapped a minimal area of overlapping deletions to a 1-centimorgan region, which is separate from the Carney complex locus. LOH for a microsatellite marker (PYGM), very close to the MEN1 gene, was detected in all 8 informative carcinomas (100%) and in 2 of 14 adenomas. Of the 27 cases analyzed in detail, 13 cases (11 carcinomas and 2 adenomas) showed LOH on chromosome 11 and was therefore selected for MEN1 gene mutation analysis. In 6 cases a common polymorphism (Asp418Asp) was found, but no mutation was detected. In conclusion, our data indicate the existence of tumor suppressor genes at multiple chromosomal locations, whose inactivations are involved in the development of adrenocortical carcinomas. Loss of genetic material from 2p16 was strongly associated with the malignant phenotype, as it was seen in almost all carcinomas but not in any of the adenomas. LOH in 11q13 also occurred frequently in the carcinomas, but was not associated with a MEN1 mutation, suggesting the involvement of a different tumor suppressor gene on this chromosome.

Alterations of the MEN1 gene in sporadic parathyroid tumors.

Primary hyperparathyroidism is a common endocrine disease that also occurs in a number of inherited disorders, including multiple endocrine neoplasia type 1 (MEN1). Loss of heterozygosity (LOH) in the MEN1 region on chromosome 11q13 has been found in 30% of sporadic parathyroid tumors, making the recently cloned MEN1 gene a prime candidate for involvement in parathyroid tumorigenesis. Using LOH and single strand conformation analysis, we screened 45 sporadic tumors from 40 patients for alterations involving the MEN1 gene. Thirteen tumors showed LOH at 11q13, and in 6 of these cases, somatic mutation of the MEN1 gene was detected. In tumors without LOH, no mutations were detected. The mutations consisted of 3 small deletions, 1 insertion, and 2 missense mutations that had not been reported in MEN1 patients or parathyroid tumors previously. Using messenger ribonucleic acid in situ hybridization, the expression of the MEN1 gene was studied. There was no difference in expression between normal and tumor tissue. In conclusion, the findings of inactivating mutation in tumors with LOH at 11q13 confirm the role of the MEN1 tumor suppressor gene in a subset of sporadic parathyroid tumors.

Alternative genetic pathways in parathyroid tumorigenesis.

In this study 44 parathyroid tumors from 26 sporadic cases, 10 cases previously given irradiation to the neck, and 8 familial cases were screened for sequence copy number alterations by comparative genomic hybridization. In the sporadic adenomas, commonly occurring minimal regions of loss could be defined to chromosome 11 (38%), 15q15-qter (27%), and 1p34-pter (19%), whereas gains preferentially involved 19p13.2-pter (15%) and 7pter-qter (12%). Multiple aberrations were found in sporadic tumors with a somatic mutation and/or loss of heterozygosity of the MEN1 gene. The irradiation-associated tumors also showed multiple comparative genomic hybridization alterations and frequent losses of 11q (50%), and subsequent analysis of the MEN1 gene demonstrated mutations in 4 of 8 cases (50%). The adenomas from familial cases showed few alterations, and in 3 of these tumors a gain of 19p13.2-pter was seen as the only aberration. In this study numerical copy number alterations were frequently detected in sporadic and irradiation-associated parathyroid adenomas, although these tumors are benign. The majority of these alterations were found in tumors with confirmed involvement of the MEN1 gene locus in agreement with a role of the MEN1 gene in genomic stability. Furthermore, the frequent occurrence of MEN1 mutations (50%) in irradiation-associated parathyroid tumors suggests that inactivation of the MEN1 gene is an important genetic alteration involved in the development of parathyroid tumors in postirradiation patients.

Familial isolated hyperparathyroidism maps to the hyperparathyroidism-jaw tumor locus in 1q21-q32 in a subset of families.

Approximately 70 families with familial isolated hyperparathyroidism (FIHP) have been reported. Whether it is a separate entity or a variant of multiple endocrine neoplasia type 1 (MEN1 at 11q13) or hyperparathyroidism-jaw tumor (HPT-JT or HRPT2 at 1q21-32) syndrome is not known. We describe here 3 unreported families with familial primary hyperparathyroidism and evaluate their clinical, pathological, and genetic profiles. Biochemical and radiological screenings for MEN1 were negative for all families. In 2 families with a total of 10 affected cases and 3 female obligate carriers, there is no evidence of jaw or renal lesions despite careful radiological investigations. In both families the disease was linked to the 1q21-q32 region with the maximum logarithm of the odds (lod) scores of 3.10 and 3.43 for markers D1S222 and D1S249 respectively, at recombination fraction of 0. In 1 family 2 types of parathyroid pathology were found: 3 of chief cell type and 1 of oxyphil/oncocytic cell type. Two chief cell tumors and 1 oxyphil tumor were found to have loss of heterozygosity (LOH) involving loss of the wild-type alleles for chromosome 1q markers. In the third family, with 4 affected siblings, a parathyroid carcinoma and 2 cases of polycystic kidney disease were found. The parathyroid carcinoma also showed loss of heterozygosity in the 1q region. In conclusion, we found that the hyperparathyroidism traits in a subset of FIHP families are linked to the 1q21-32 markers in the HRPT2 region. We describe the spectrum of parathyroid disease in 1q-linked families involving 3 different types of pathology and demonstrate for the first time loss of wild-type alleles in these parathyroid tumors. Taken together, the results suggest that some of the FIHP are a variant of HPT-JT and that the gene involved is a tumor suppressor gene.