A minisatellite and a microsatellite polymorphism within 1.5 kb at the human muscle glycogen phosphorylase (PYGM) locus can be amplified by PCR and have combined informativeness of PIC 0.95

Genome-wide characterization of microsatellites in Triticeae species: abundance, distribution and evolution

Microsatellites are an important constituent of plant genome and distributed across entire genome. In this study, genome-wide analysis of microsatellites in 8 Triticeae species and 9 model plants revealed that microsatellite characteristics were similar among the Triticeae species. Furthermore, genome-wide microsatellite markers were designed in wheat and then used to analyze the evolutionary relationship of wheat and other Triticeae species. Results displayed that Aegilops tauschii was found to be the closest species to Triticum aestivum, followed by Triticum urartu, Triticum turgidum and Aegilops speltoides, while Triticum monococcum, Aegilops sharonensis and Hordeum vulgare showed a relatively lower PCR amplification effectivity. Additionally, a significantly higher PCR amplification effectivity was found in chromosomes at the same subgenome than its homoeologous when these markers were subjected to search against different chromosomes in wheat. After a rigorous screening process, a total of 20,666 markers showed high amplification and polymorphic potential in wheat and its relatives, which were integrated with the public available wheat markers and then anchored to the genome of wheat (CS). This study not only provided the useful resource for SSR markers development in Triticeae species, but also shed light on the evolution of polyploid wheat from the perspective of microsatellites.

A novel WT1 gene mutation associated with wilms' tumor and congenital male genitourinary malformation

WT1 is located on the short arm of human chromosome 11 and consists of 10 coding exons. Mutations of this gene have been reported to be the cause of Wilms' tumor, congenital male genitourinary malformations, and/or renal disorders. We describe here a novel WT1 gene mutation, i.e. a point mutation at intron 7 (+2) in both the tumor and the germline cells of a patient with Wilms' tumor and congenital male genitourinary malformation, but without renal disorder. The position of the mutation is at a splice donor site of intron 7, which causes the splicing out of exon 7 and generates a truncated protein. This type of mutation in the WT1 zinc finger domain has not been reported before. The mutation is of paternal origin and is heterozygous in the germline cells. In the tumor cells, however, the maternal allele is largely lost, from 11p12 to 11p15, which results in maternal loss of heterozygosity. These results, together with the data from previous reports, suggest that WT1 may function in gonadogenesis, nephrogenesis, and Wilms' tumor tumorigenesis.

The human genome project: a historical perspective

Efforts in genomics over the last decade have created a stream of opportunities for drug discovery. High-throughput DNA sequencing has forced a re-definition of the paradigm for identification and validation of targets for drug development. One purpose of this review is to delineate the different approaches to sequence data generation and to establish their various uses for the definition of gene function. There still remain crucial dilemmas for the pharmaceutical industry. The multitude of potential targets can each absorb enormous validation costs and the vast majority are likely to prove academically interesting but useless for drug development. An additional dimension arises from the importance of sequence variation between different individuals. These differences can determine response to therapy and must inform both the drug development process and healthcare delivery. This presents great challenges and opportunities for drug companies, their customers and society as a whole. I will review the technological aspects in some detail and give my view of the legal and social aspects. The field of bioinformatics is at the core of functional and pharmacogenomics and advances will depend on the continuing evolution of tools to interpret data. For the most part this evolution is reviewed in the context of specific application areas rather than as a discrete field, in recognition of its all-pervasive effects.

Identification of somatic mutations of the MEN1 gene in sporadic endocrine tumours

Endocrine tumours of the pancreas, anterior pituitary or parathyroids arise either sporadically in the general population, or as a part of inherited syndromes such as multiple endocrine neoplasia type 1 (MEN 1). The mechanisms responsible for the development of sporadic endocrine lesions are not well understood, although loss of heterozygosity (LOH) of the MEN1 locus on chromosome 11q13 and somatic mutation of the MEN1 gene have been frequently associated with the development of MEN 1-type sporadic endocrine lesions. To further investigate the role of the MEN1 gene in sporadic endocrine tumorigenesis, we analysed DNA from 14 primary parathyroid lesions, 8 anterior pituitary tumours and 3 pancreatic tumours for the presence of somatic MEN1 gene mutations and LOH of seven microsatellite markers flanking the MEN1 locus. In addition, we similarly analysed 8 secondary parathyroid lesions which arose in patients with chronic renal failure. None of the patients studied had a family history of MEN 1. Three primary parathyroid lesions and one pancreatic tumour (glucagonoma) were found to have lost one allele at the MEN1 locus. Somatic mutations were identified by SSCP and sequence analysis in one of these parathyroid lesions (P320L) and in the glucagonoma (E179V). These results support previous findings that inactivation of the MEN1 tumour suppressor gene contributes to the development of sporadic MEN 1-type endocrine lesions but is not associated with the development of parathyroid hyperplasia seen in some renal failure patients.

A functional investigation of tumor suppressor gene activities in a nasopharyngeal carcinoma cell line HONE1 using a monochromosome transfer approach

Monochromosome transfers of selected chromosomes into a nasopharyngeal carcinoma (NPC) cell line were performed to determine if tumor suppressing activity for NPC mapped to chromosomes 9, 11, and 17. Current information from cytogenetic and molecular allelotyping studies indicate that these chromosomes may harbor potential tumor suppressor genes vital to NPC. The present results show the importance of CDKN2A on chromosome 9 in NPC development. There was no functional suppression of tumor development in nude mice with microcell hybrids harboring the newly transferred chromosome 9 containing an interstitial deletion at 9p21, whereas transfection of CDKN2A into the NPC HONE1 cells resulted in obvious growth suppression. Whereas intact chromosome 17 transfers into HONE1 cells showed no functional suppression of tumor formation, chromosome 11 was able to do so. Molecular analysis of chromosome 11 tumor segregants indicated that at least two tumor suppressive regions mapping to 11q13 and 11q22-23 may be critical for the development of NPC.

Clinical features of multiple endocrine neoplasia type 1 (MEN1) phenocopy without germline MEN1 gene mutations: analysis of 20 Japanese sporadic cases with MEN1

OBJECTIVE

Multiple endocrine neoplasia type 1 (MEN1) is a familial tumour syndrome of endocrine tumours involving parathyroids, anterior pituitary and enteropancreatic neuroendocrine tissues, and is inherited in an autosomal dominant manner with high penetrance. Recently, the gene responsible for this syndrome, MEN1, was positionally cloned from chromosome 11q13.

PATIENTS

To characterize sporadic MEN1 patients, we analysed the MEN1 gene by direct sequencing of the entire open reading frame from 20 individuals.

RESULTS

We identified heterozygous germline mutations of the MEN1 gene in 8 of 20 (40%) cases. Seven were novel MEN1 germline mutations. Three mutations were splicing abnormalities, and all were confirmed to be splicing defects by RT-PCR. The clinical significance of detecting germline MEN1 mutations, not only in familial MEN1 but also in sporadic MEN1, was confirmed by the finding of asymptomatic mutant carriers among family members of the sporadic MEN1 patients. Seven of 8 cases with MEN1 mutations had enteropancreatic lesions in contrast to 4 of 12 (P < 0.018) in those cases with no mutation. Ten of the 12 cases without MEN1 mutation were more than 50-year-old. Six of these 10 cases had the same clinical features; primary hyperparathyroidism and a GH-secreting pituitary tumour.

CONCLUSIONS

It is likely that the six cases without mutations were MEN1 phenocopies due to (i) two kinds of tumours with high natural incidence in older subjects developed by chance (ii) another familial tumour syndrome with low penetrance, e. g. familial acromegaly with primary hyperparathyroidism by mutation of another gene, or (iii) somatic mutation during early embryonic stages.

Pathology of MEN-1: morphology, clinicopathologic correlations and tumour development

Multiple endocrine neoplasia type 1 (MEN-1) is an inherited syndrome which is characterized by the occurrence of neoplastic lesions in the parathyroids, the pancreas, duodenum, anterior pituitary and, less commonly, also in the stomach, thymus and lung. Its genetic defect has recently been identified and appears to involve a new type of tumour suppressor gene called mu on chromosome 11q13. In this overview, we will summarize the morphological features of the MEN-1 phenotype, discuss its clinicopathologic profile and prognosis and outline the recent findings on the molecular pathology of this syndrome.

Absence of germ-line mutations of the multiple endocrine neoplasia type 1 (MEN1) gene in familial pituitary adenoma in contrast to MEN1 in Japanese

Germ-line mutations of the MEN1 gene were analyzed in five cases of familial and four cases of sporadic multiple endocrine neoplasia type 1 (MEN-1), six cases in three independent pedigrees of familial pituitary adenoma without MEN-1, and three cases of familial isolated primary hyperparathyroidism (FIHP) in Japanese. Eight different types of germ-line mutations in all nine cases of MEN-1 were distributed in exons 2, 3, 7, and 10 and intron 7 of the MEN1 gene. Loss of heterozygosity (LOH) on 11q13 was detected in all nine tumors of these cases with microsatellite analysis. No germ-line mutation of the MEN1 gene was detected in three pedigrees of familial pituitary adenoma and three cases of FIHP. LOH on 11q13 was detected in two cases in one pedigree of familial pituitary adenoma, and one of them showed a heterozygous somatic mutation of the MEN1 gene. No LOH on 11q13 was detected in three cases of FIHP. Based on these, we conclude that the loss of function of menin is etiological for familial or sporadic MEN-1, but not for FIHP or most familial pituitary adenoma without MEN-1.

Allelic loss in parathyroid tumors from individuals homozygous for multiple endocrine neoplasia type 1

Homozygosity for the multiple endocrine neoplasia type 1 (MEN1) gene mutation was described in two of three affected siblings of a kindred in which both parents and the third daughter were heterozygotes. Surprisingly, in the two homozygotes, the disease history did not differ from the one of the heterozygotes. In the attempt to unravel genetic differences in parathyroid tumorigenesis between homozygotes and heterozygotes, restriction fragment length polymorphism analysis and microsatellite PCR analysis for loss of heterozygosity (LOH) at the MEN1 gene region on chromosome 11q13 was performed in parathyroid tissues removed at surgery from the mother, her heterozygous sister, and the three siblings. Allelic losses were evidenced in the larger glands of each patient, with a similar pattern of chromosome 11q12-13 losses. The somatic mutation consisted of a large lose of genetic material from chromosome 11. No gross differences exist in the 11q12-13 LOH observed between homozygous and heterozygous carriers. Interestingly, one of the parathyroid tumors from one heterozygote exhibited region of skipped LOH at the 11q12-13 region. The region in the depth of the critical interval retained heterozygosity, whereas those flanking it shared LOH. These findings indicate that inactivation of both copies of the MEN1 gene are not sufficient for parathyroid tumor development in MEN 1 patients and that tumor suppressor genes, other than the MEN1 gene on chromosome 11 or on other chromosomes, can be involved in the pathogenesis of parathyroid tumorigenesis in MEN 1 syndrome.

Homozygosity by descent for a rare mutation in the myophosphorylase gene is associated with variable phenotypes in a Druze family with McArdle disease

We examined a large consanguineous Druze family with McArdle disease for mutations in the glycogen myophosphorylase (PYGM) gene. All affected subjects were autozygous for a single G to A transition that abolishes the 5' consensus splice site in the first nucleotide of intron 14. The G to A transition is a rare mutation, with only one previous report in a single white subject heterozygous for this mutation and another, more common, mutation at codon 49. The kindred in our study is the first family reported in which disease is caused by homozygosity for this rare mutation. This kindred was originally reported as the first familial case of McArdle disease in the Druze.

Loss of heterozygosity on chromosome 11q13 in lobular lesions of the breast using tissue microdissection and polymerase chain reaction

Demonstration of identical allelic loss on chromosome 11q13 in synchronous in situ (DCIS) and invasive ductal (IDC) breast carcinoma has provided molecular evidence of the progression of DCIS to IDC. We investigated loss of heterozygosity (LOH) at chromosome 11q13 in the spectrum of "marker/premalignant" and "malignant" lobular lesions of the breast, including atypical lobular hyperplasia (ALH), lobular carcinoma in situ (LCIS), and infiltrating lobular carcinoma (ILC). Thirty-eight cases with various combinations of ALH, LCIS, and ILC were studied. Synchronous ductal lesions were present in 9 of 38 cases. Areas of interest were specifically isolated by tissue microdissection. The extracted DNA was amplified by polymerase chain reaction (PCR) and analyzed with two polymorphic markers for chromosome 11q13 (INT2 and PYGM). LOH at 11q13 was identified in ILC and LCIS in approximately one third of informative cases. LCIS in association with ILC showed a loss in 50% of cases, whereas pure LCIS in the absence of ILC had a much lower frequency of LOH, which was comparable to that of pure ALH. These results suggest that LOH on chromosome 11q13 may play an important role in development of ILC, similar to that of IDC from DCIS/ADH. Additionally, frequent LOH in ILC and LCIS associated with ILC and a significantly lower and comparable frequency of LOH in LCIS without ILC and ALH implies that genetic alteration(s) on chromosome 11q13 may be important in the transition of LCIS to ILC. LOH was detected in three of nine synchronous ductal lesions (one IDC and two DCIS), confirming our earlier findings and indicating that lobular and ductal neoplasia in the breast show some similar genetic changes. We hypothesize that LOH may help in separating morphologically similar yet genetically different subgroups of ALH and LCIS into one group with genetic changes and an increased potential to progress to invasive cancer and another group, the "marker" lesions of LCIS/ALH, that remain stable or possibly regress.

Genetic screening in hereditary multiple endocrine neoplasia type 1: absence of a founder effect among Japanese families

Ten Japanese families with hereditary multiple endocrine neoplasia type 1 (MEN1) were examined. Five DNA polymorphic markers on the long arm of chromosome 11 were analyzed for genetic screening of MEN1 in members of affected families, and disease carriers were identified before clinical manifestations. Unlike MEN1 families in Newfoundland or in Tasmania, no consistent haplotypes were segregated with the disease in the Japanese families when defined by 5 nearby markers. The identification of asymptomatic disease carriers is of substantial clinical importance for early management, genetic counseling and to avoid unnecessary screening for non-disease carriers. However, genetic screening of family members by polymorphic markers could be useful only to each family, and no generally applicable markers were found for Japanese subjects with MEN1.

Chromosomal 11 alterations in non-small-cell lung carcinomas in Hong Kong

We examined 60 non-small-cell lung cancer (NSCLC) patients for evidence of genetic alterations on chromosome 11 with nine polymorphic markers by Southern blot and microsatellite marker analysis. These analyses detected genetic alterations at both the 11p and 11q arms. At the 11p15 Ha-ras locus, the loss of heterozygosity (LOH) occurred in three out of 11 (27.3%) of the informative cases; at the 11p11-q12 D11S149 locus, the LOH occurred in two out of nine (22.2%) of the informative cases; and at the 11q13 INT-2 locus, the LOH occurred in four out of 18 (22.2%) of the informative cases. Microsatellite markers in the 11q12-q13 region revealed genetic alterations for PYGM in eight out of 54 (14.8%) of the specimens studied and 10 out of 55 (18.2%) of the specimens for the INT-2 marker. The data suggest genetic alterations occur in some of the lung cancer patients in both the 11p and 11q regions.

Genetic mapping studies of 40 loci and 23 cosmids in chromosome 11p13-11q13, and exclusion of mu-calpain as the multiple endocrine neoplasia type 1 gene

Forty loci (16 polymorphic and 24 non-polymorphic) together with 23 cosmids isolated from a chromosome 11-specific library were used to construct a detailed genetic map of 11p13-11q13. The map was constructed by using a panel of 13 somatic cell hybrids that sub-divided this region into 19 intervals, a meiotic mapping panel of 33 multiple endocrine neoplasia type 1 (MEN1) families (134 affected and 269 unaffected members) and a mitotic mapping panel that was used to identify loss of heterozygosity in 38 MEN1-associated tumours. The results defined the most likely order of the 16 loci as being: 11pter-D11S871-(D11S288, D11S149)-11cen-CNTF-PGA-ROM1-D11S480-PYGM- SEA-D11S913-D11S970-D11S97- D11S146-INT2-D11S971-D11S533-11qter. The meiotic mapping studies indicated that the most likely location of the MEN1 gene was in the interval flanked by PYGM and D11S97, and the results of mitotic mapping suggested a possible location of the MEN1 gene telomeric to SEA. Mapping studies of the gene encoding mu-calpain (CAPN1) located CAPN1 to 11q13 and in the vicinity of the MEN1 locus. However, mutational analysis studies did not detect any germ-line CAPN1 DNA sequence abnormalities in 47 unrelated MEN1 patients and the results therefore exclude CAPN1 as the MEN1 gene. The detailed genetic map that has been constructed of the 11p13-11q13 region should facilitate the construction of a physical map and the identification of candidate genes for disease loci mapped to this region.

Different allelic patterns at chromosome 11q13 in paired aldosterone-producing tumours and blood DNA

1. We previously reported loss of heterozygosity (LOH) at region q13 of chromosome 11 in five aldosterone-producing tumours (APT) using restriction fragment length polymorphism (RFLP) analysis, including two from patients with familial hyperaldosteronism. 2. In the present study, microsatellite markers were used to examine 33 informative paired blood and tumour DNA samples from patients with APT for LOH at three loci that map to chromosome 11q13. 3. LOH at one or more loci was detected in seven (21.2%) tumour DNA samples. 4. This study provides further support that mutations at 11q13 may be involved in the underlying pathophysiology of aldosterone-producing tumours of the adrenal cortex.

Predictive diagnosis of multiple endocrine neoplasia (MEN 1) in four Australian kindreds

BACKGROUND

Multiple endocrine neoplasia type 1 (MEN 1) is a tumour predisposition syndrome that usually manifests in the first four decades of life. It has an autosomal dominant mode of inheritance which means that any new member of a MEN1 kindred has roughly a 50% chance of developing the disorder during their lifetime. The localisation of the MEN1 gene to a small region of chromosome band 11q13 has led to the development of DNA-based predictive diagnosis for this disease.

AIMS

To establish a polymerase chain reaction (PCR)-based system, using simple tandem repeat polymorphisms (STRPs), to predict gene carriers in four Australian MEN 1 kindreds.

METHODS

Six STRP markers flanking the MEN1 region of chromosome band 11q13 were used to screen individuals for a common haplotype in order to determine carrier status.

RESULTS

The accuracy of prediction was calculated to be > 95% in informative individuals.

CONCLUSIONS

DNA-based presymptomatic detection of affected members of MEN 1 kindreds could facilitate their care and reduce the inconvenience and expense of repeated testing of unaffected members. However, due to occasional recombination events or uninformativeness of markers in certain individuals, carrier status cannot always be predicted.

Molecular tools for presymptomatic testing in multiple endocrine neoplasia type 1

The aim of this workshop session was to define a set of molecular tools for pre-clinical diagnosis in affected families, and to assess presence or absence of linkage to 11q13 in families with classical MEN1 as well as with MEN1-related clinical features. A consensus linkage map of first- and second-choice markers based on PCR as well as Southern blotting was established at the workshop. Based on the results from linkage analysis in 87 families with classical MEN1, presymptomatic testing using the suggested panel of markers, can now be performed with great accuracy.

Multiple endocrine neoplasia type 1 in France: clinical and genetic studies

Multiple endocrine neoplasia type 1 (MEN1) is a hereditary syndrome characterized by the involvement of several endocrine glands, including the parathyroid glands, the pancreatic islet cells, the anterior pituitary gland and other neuroendocrine tissues. In order to build up a French MEN1 register, a collaborative network was developed through the 'Groupe d'Etude des Néoplasies Endocriniennes Multiples de type 1' or GENEM 1. A 2-year follow-up in 40 medical and surgical units allowed the identification of more than 150 individual patients and 45 MEN1 families, and defined the major clinical features of the disease in our series. Multiple endocrine neoplasia type 1 is inherited as an autosomal dominant trait. The gene causing this syndrome has been localized to chromosome 11, band 11q13, and molecular genetic markers flanking the MEN1 locus are of use in identifying disease gene carriers in predisposed families. Selected data were presented in order to discuss the management of patients by combined clinical, biochemical and genetic screening. The set-up of a national register by a multi-disciplinary and collaborative medical and surgical network will facilitate further research on the clinical management of MEN1 patients and the basic physio-pathology of the disease.

Linkage studies in a kindred from Oklahoma, with familial benign (hypocalciuric) hypercalcaemia (FBH) and developmental elevations in serum parathyroid hormone levels, indicate a third locus for FBH

A five-generation kindred (19 affected, two obligate carriers and 20 unaffected) from Oklahoma USA, in which familial benign (hypocalciuric) hypercalcaemia (FBH) was associated with a developmental elevation in serum parathyroid hormone (PTH) levels, has been investigated for linkage to the candidate chromosomal regions 3q21-q24 and 19p13.3, 11q13, and 11p15, to which the genes for FBH, multiple endocrine neoplasia type 1 (MEN1) and PTH have been mapped respectively. By means of 17 polymorphic markers from these regions, linkage was excluded [LOD scores < -2.00 at (theta) = 0.05-0.25]. In addition, an analysis of multipoint crossovers and use of the LINKMAP program confirmed the exclusion from these regions. Thus, this form of FBH, designated the Oklahoma variant FBH(Ok), is not linked to markers that segregate with FBH, MEN1 and PTH; our results indicate further genetic heterogeneity and the presence of a third locus for FBH.

Purification and isoenzymic composition of glycogen phosphorylase b from normal and abnormal (PSE) muscles

Ion exchange chromatography and preparative isoelectric focusing allowed the identification of five isoenzymes of glycogen phosphorylase b from the longissimus dorsi muscle of normal pigs and those prone to having pale, soft and exudative (PSE) muscle. The isoelectric point of the isoenzymes varied in the pH range from 6.29 to 6.55. One of them, with an isoelectric point at about a pH of 6.49, accounts for 65% of the total glycogen phosphorylase b activity. No significant differences between normal and PSE-prone pigs were observed in the total glycogen phosphorylase b activity and in the isoenzyme distribution pattern. It is concluded that the fast glycogen turnover in PSE-prone pigs is not due to a different isoenzyme pattern of phosphorylase b.

Genetic screening to identify the gene carrier in Italian and German kindreds affected by multiple endocrine neoplasia type 1 (MEN 1) syndrome

Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominantly inherited disorder characterized by parathyroid hyperplasia, anterior pituitary adenomas and neoplasms of the endocrine cells of the gastroenteric tract. It has been established that also other tissues exhibit excessive proliferation associated to the MEN 1 syndrome: carcinoids (bronchial and intestinal), lipomas (visceral and cutaneous), thyroid adenomas and goiter, and adrenal gland cortex adenomas. The men 1 gene has been mapped by genetic studies to the long arm of human chromosome 11, region q12-13. Genetic analysis of families and tumoral deletion mapping made possible to narrow the men 1 region to a 5 cM interval on chromosome 11q12-13. Thirteen marker complexes (17 DNA probes) were found to be linked to the men 1 gene and they span a 14% meiotic recombination with the men 1 locus in the middle. We report a genetic study on 103 subjects from 7 collected MEN 1-kindreds, six Italian and one German, including 30 affected individuals. By linkage analysis to 9 DNA markers (10 DNA probes) of the chromosome region where the men 1 gene maps (11q12-13), we identified 10 mutant gene carriers. The predicted MEN 1 diagnosis was clinically confirmed for 2 of these identified carriers. A predictive accuracy of this genetic test can reach up to 99.5% when it is possible to exclude meiotic crossing-over between the analyzed DNA markers and the disease locus.

Molecular Diagnosis of Multiple Endocrine Neoplasia (MEN) in Paraffin-Embedded Specimens

In this article, we summarize our recent findings on rearranged during transfection (RE7) mutations in a series of 46 sporadic as well as multiple endocrine neoplasia (MEN) type 2- associated tumors and present results of our family screening efforts to identify MEN 2 and MEN 1 gene carriers. A nonisotopic polymerase chain reaction-based single-strand conformation polymorphism (PCR-SSCP) analysis and heteroduplex gel electrophoresis method was used to screen DNA extracted from archival specimens of 22 patients with MEN 2-associated and 24 patients with sporadic tumors for mutations in RETexons 1O, 11, 13, and 16. Point mutations were identified by nonisotopic cycle sequencing of PCR products using an automated DNA sequencer. We found six different missense germ line mutations at cysteine residues encoded by exons 10 and 11 in all patients with MEN 2A or familial medullary thyroid carcinoma (FMTC). The frequency of mutations at codon 634 was higher in patients with MEN 2A than with FMTC and a (63)Cys - Arg mutation was associated with parathyroid disease. A germline Met -* Thr point mutation at codon 918 of the RETtyrosine kinase domain encoded by exon 16 was identified in all MEN 2B patients. Nonpredicted inheritable medullary thyroid carcinomas (MTCs) were detected in two patients and a mosaic postzygotic mutation was found in one additional patient. Tumor-specific (somatic) Met - Thr point mutations at codon 918 were identified in 5 of 13 sporadic MTCs and 2 of 8 sporadic pheochromocytomas (PCCs). The remaining sporadic tumors lacked mutations in all four RET exons tested. In exon 13, a nucleic acid polymorphism (CTT/CTG; Leu) at codon 769 was identified, which is present in approx 40% of the examined population. Our study demonstrates that the molecular methods used are not only suitable to identify asymptomatic individuals at risk for MEN 2A, FMTC, and MEN 2B, but also to distinguish sporadic from inherited tumors using archival tissue specimens; and that more tumors than clinically expected are inheritable, indicating the need for genetic analysis of all MTC and PCC patients.

Loss of heterozygosity in cervical carcinoma: subchromosomal localization of a putative tumor-suppressor gene to chromosome 11q22-q24

Infection of cervical epithelial cells with so-called "aggressive" subtypes of human papilloma virus (HPV) appears to be an important factor in the etiology of cervical carcinoma. However, mounting evidence suggests that additional genetic changes are required for progression to an invasive carcinoma. Functional studies have shown that human chromosome 11 contains a gene or genes capable of suppressing tumorigenicity in cell lines derived from different histopathological types of cervical carcinoma, suggesting that aberration of this gene(s) may represent at least one of the additional changes required for tumorigenic progression. To identify the likely chromosomal position of this gene(s), we have carried out a systematic genetic analysis of chromosome 11 in the primary tumors of 32 patients with cervical carcinoma. Sixteen highly polymorphic markers, 10 of which were based on simple sequence repeats typed by PCR, were used to compare matched DNA samples from noninvolved tissue and portions of tumor tissue highly enriched for neoplastic cells by the cryostat-sectioning technique. Of the 32 patients examined, 14 (44%) demonstrated clonal genetic alterations resulting in loss of heterozygosity for one or more markers. Seven of the clonal genetic alterations on chromosome 11 were specific to the long arm, and the overlap between these and other allelic deletions suggests that a suppressor gene(s) relevant to cervical carcinoma maps to chromosome 11q22-q24.

Family screening in multiple endocrine neoplasia type 1 (MEN 1)

Multiple endocrine neoplasia type 1 is an autosomal dominantly inherited disorder predisposing to development of neoplastic lesions in the parathyroid glands, the neuro-endocrine pancreas-duodenum and the anterior pituitary. The genetic defect was mapped to the centromeric region of the long arm of chromosome 11, based on studies of somatic deletions in MEN 1-associated tumours and linkage analysis in affected families. Combined family and tumour analyses have shown that tumourigenesis in MEN 1 involves loss of the wild type chromosome, indicating that the putative MEN 1 gene is a tumour suppressor gene. Based on results from linkage analysis in more than 40 MEN 1 families, presymptomatic testing for MEN 1 using DNA polymorphisms can now be performed with high accuracy. Hence, biochemical screening programmes can focus on individuals at risk, in order to identify early signs of tumour development.

Molecular evidence for non-penetrance in Best's disease

The present study provides evidence for a possible case of non-penetrance in Best's disease. We have analysed the at risk members of a three generation family with an established history of Best's disease by ophthalmoscopic examination, electrophysiological tests, and genetic analysis. The clinical examination identified 10 affected and five unaffected persons in this family. Genetic linkage analysis strongly supports linkage of the disease locus to DNA microsatellite markers from proximal 11q. The genotyping data were used to construct the familial haplotype associated with Best's disease. One person was identified who has inherited the Best's disease haplotype from his affected mother. Fundus examination and electrophysiological tests have repeatedly been performed in this patient but failed to show any signs of the disease. Based on these findings we have jointly estimated the most likely order of the Best's disease locus relative to the closet flanking markers at various penetrance values. A maximum likelihood estimate for the heterozygote penetrance was reached for the locus order D11S903-Best's disease-PYGM at a penetrance value of 0.96.

Bardet-Biedl syndrome is linked to DNA markers on chromosome 11q and is genetically heterogeneous

Bardet-Biedl syndrome (BBS) is an uncommon autosomal recessive condition characterized by mental retardation, post-axial polydactylia, obesity and pigmentary retinopathy. We performed linkage analysis in 31 multiplex BBS families and report significant linkage with two markers on chromosome 11q, PYGM and AFM164zf12 (D11S913). Homogeneity testing demonstrates genetic heterogeneity within our set of families. Our data imply that a major gene, BBS1, is located on chromosome 11q, although mutations at other loci may also be associated with this phenotype.

Chromosome 11q13 and atopy underlying atopic eczema

Genetic linkage has been reported between atopic respiratory disease and chromosome site 11q13. We recruited 95 multiplex families through probands with active atopic eczema. Linkage analyses between atopy and markers on 11q13 excluded a major susceptibility locus for atopy in this region. Nor was there significant deviation from the expected proportions of alleles shared by affected sib-pairs. When we analysed families according to parental atopic phenotype, we observed a positive lod score (0.8) in 19 families with unaffected fathers, in contrast to markedly negative scores for other combinations of affected parental phenotype. The possibility of a maternal influence on the inheritance of atopy cannot, therefore, be excluded.

Linkage analysis of 7 polymorphic markers at chromosome 11p11.2-11q13 in 27 multiple endocrine neoplasia type 1 families

The multiple endocrine neoplasia type 1 (MEN1) locus has been previously localized to 11q13 by combined tumour deletion mapping and linkage studies. Family linkage analysis has defined the locus order as 11 cen-PGA-(PYGM, MEN1)-(D11S97, D11S146)-INT2-11qter, and tumour deletion mapping studies have suggested that the MEN1 locus is proximal to D11S146 but distal to PYGM. In order to establish further the location of MEN1, we have utilized the seven polymorphic DNA probes: D11S288, D11S149, PGA, PYGM, D11S97, D11S146 and INT2, in linkage studies of 339 members (116 affected) from 27 MEN1 families. Linkage between MEN1 and 6 of the 7 loci was established, and the highest peak lod scores [Z(theta)] were observed with PYGM and D11S97 at Z(theta) = 13.71, theta = 0.047 and Z(theta) = 13.76, theta = 0.076 respectively. Multilocus analysis suggested the most likely locus order as: 11 pter-(D11S288, D11S149)-11 cen-PGA-PYGM-MEN1-D11S97-D11S146-INT2-1 1qter. In addition, an examination of individual recombinants indicated a centromeric location of D11S149 in relation to D11S288. Thus, the results of our study, which favoured a location of MEN1 proximal to D11S97 and distal to PYGM, have established a panel of recombinants that will facilitate further meiotic mapping studies of the MEN1 locus.

The gene for Best's macular dystrophy is located at 11q13 in a Swedish family

A large Swedish family with more than 250 cases of Best's macular dystrophy has been clinically and genetically studied. The gene was traced to a couple born in central Sweden in the 17th century. Highly significant evidence for genetic linkage to DNA markers on chromosome 11q13 was detected. A lod score of 15.12 was obtained at recombination fraction 0.01 with DNA marker INT2 (also called FGF3). The retinally expressed gene ROM1, which maps to the same chromosomal region is a candidate for this genetic disease.