Molecular genetic studies of sporadic pituitary tumors.

Tumor formation may result from the activation of dominant oncogenes or by inactivation of recessive, tumor suppressor genes. The role of such mutations in the development of pituitary tumors has been studied. Tumors from 88 patients, representing the 4 major classes of adenoma, were investigated. In DNA extracted from matched leukocyte and tumor samples, allelic deletions were sought with 15 probes identifying restriction fragment length polymorphisms on chromosomes 1, 5, 10, 11, 13, 17, 20, and 22. Evidence of amplification or rearrangement of 10 recognized cellular oncogenes (N-ras, mycL1, mycN, myc, H-ras, bcl1, H-stf1, sea, kraS2, and fos) was sought in tumor DNA. Activating dominant mutations of Gs alpha were detected using the polymerase chain reaction to amplify exons 7-10 and hybridizing the product to normal and mutant allele-specific oligonucleotides. Allelic deletions on chromosome 11 were identified in 16 tumors (18%) representing all 4 major subtypes. Deletions on other autosomes were observed in less than 6% of tumors. Three adenomas had deletions on multiple autosomes, 2 of these were aggressive and recurrent. Mutations of Gs alpha were confirmed to be specific to somatotrophinomas, being identified in 36% of such tumors in this series. No evidence of amplification or rearrangement of other recognized cellular oncogenes was found. Inactivation of a recessive oncogene on chromosome 11 is an important and possibly early event in the development of the four major types of pituitary adenoma, whereas activating mutations of Gs alpha are confirmed to be specific to somatotropinomas. Two aggressive tumors were found to have multiple autosomal losses, suggesting a multistep progression in the development of tumors of this phenotype.

Glutathione S-transferase polymorphisms in MS: their relationship to disability.

BACKGROUND: Oxidative stress has been implicated in inflammatory demyelination. The glutathione S-transferase (GST) supergene family encodes isoenzymes that appear to be critical in protection against oxidative stress. Certain GST loci are polymorphic, demonstrating alleles that are null (GSTM1/GSTT1), encode low activity variants (GSTP1), or are associated with variable inducibility (GSTM3). OBJECTIVES: To investigate the association between clinical outcome in MS and allelic variants of GSTM1, GSTM3, GSTT1, and GSTP1. METHODS: Four hundred patients with clinically definite MS were studied. Disability was measured using the Kurtzke Expanded Disability Status Scale (EDSS). Disability was graded as mild (EDSS 0-4), moderate (4.5-5.5), or severe (EDSS 6-10). PCR-based genotyping was performed using DNA extracted from lymphocytes. Significant associations between GST genotypes and clinical outcome were corrected for gender, onset age, and disease duration using logistic regression. RESULTS: We found that the GSTM3 AA genotype was associated with severe disability in patients with a disease duration of more than 10 years (p = 0.027, n = 177, OR = 2.4, 95% CI = 1.1-5.0). Homozygosity for both GSTM1*0 and GSTP1*Ile105 containing allele was associated with severe disability in patients with a disease duration greater than 10 years (p = 0.022, n = 179, OR = 5.0, 95% CI = 1.3-19.8). CONCLUSIONS: Our results suggest that long-term prognosis in MS is influenced by a genetically determined ability to remove the toxic products of oxidative stress.

Interleukin 1 genotypes in multiple sclerosis and relationship to disease severity.

We studied the association between clinical outcome in MS and allelic variants single nucleotide polymorphisms (SNPs) of interleukin-1alpha (IL-1alpha), IL-1beta and a variable number tandem repeat (VNTR) in IL-1 receptor antagonist (IL-1RN). A total of 377 patients with MS were studied. Significant associations between IL-1 genotypes and clinical outcome were found using logistic regression after correction for gender, onset age and disease duration. The same trends were subsequently demonstrated in a second independent group of 67 primary progressive patients. Our results suggest that genetically determined immunomodulation mediated by IL-1 influences long-term prognosis in multiple sclerosis (MS).

HLA-DRB1 and disease outcome in multiple sclerosis.

The association between susceptibility to multiple sclerosis (MS) and the class II MHC allele HLA-DRB1*15 is well established although a possible relationship between this allele and outcome in MS is less clear. HLA-DRB1 typing was performed on 375 unrelated white patients with clinically definite MS and on 367 healthy controls. Putative associations of the gene with outcome were examined by dividing patients into two groups: those with an EDSS of 0-5.5 (mild/moderate disease) and those with an EDSS of 6-10 (severe disease). In order to minimise the effects of disease variability patients with a disease duration of at least 10 years or 15 years were examined. As subsidiary HLA-DRB1*03 and HLA-DRB1*04 associations have been previously reported, the effect of these alleles was also examined. As expected, HLA-DRB1*15 was found more frequently in patients than in controls (P < 0.000001). HLA-DRB1*15 positive patients had a significantly earlier age at onset than HLA-DRB1*15 negative patients. No significant associations were noted between HLA-DRB1*15 and outcome in the total patient group or in patients with a disease duration of 10 years or longer. In patients with a disease duration of at least 15 years HLA-DRB1*15 negative status was associated with a worse prognosis, although this did not remain significant after correction for multiple testing. It is thus likely that the contribution of HLA in MS is primarily towards onset and initial triggering mechanisms rather than influencing disease progression, chronicity and severity.

Acetonitrile ingestion: delayed onset of cyanide poisoning due to concurrent ingestion of acetone.

A fatal case of acetonitrile ingestion is reported. The patient presented having apparently taken an overdose but was well until around 24 hours after the supposed ingestion, when cardiovascular collapse and profound metabolic acidosis developed. Later investigation revealed that the patient had taken acetone and acetonitrile. Acetone is known to slow the metabolism of acetonitrile to cyanide, thereby delaying the appearance of toxicity.

Cerebral venous sinus thrombosis and antiphospholipid antibodies.

We report two cases of cerebral venous sinus thrombosis associated with an antibody to phospholipids, namely the lupus anticoagulant. Both patients later developed further immunologically mediated conditions. The importance of screening for the lupus anticoagulant in addition to anticardiolipin antibodies in this condition and the need for follow-up of such patients is discussed.

Cortical plaques visualised by fluid-attenuated inversion recovery imaging in relapsing multiple sclerosis.

Fluid-attenuated inversion recovery (FLAIR) imaging with prolonged inversion times allows generation of highly T2-weighted images of the brain with suppression of cerebrospinal fluid signal. Such sequences result in high lesion contrast and allow visualisation of abnormalities not seen with conventional T2-weighted spin-echo sequences. We used FLAIR sequences, proton density (PD) and standard T2-weighted images to examine lesion number and distribution in ten patients with clinically definite relapsing multiple sclerosis (MS). We also studied the extent and distribution of blood-brain-barrier breakdown by gadolinium-enhanced T1-weighted images. FLAIR sequences proved feasible both in terms of acquisition time and image quality using a 0.5 T imager. FLAIR imaging allowed identification of 45% more high-signal lesions than T2-weighted or PD images in the 10 patients. In particular, 60% more lesions within the cortex and at the grey-white interface were identified. Cortical lesions, none of which enhanced following gadolinium-DTPA injection, were present in seven of the ten patients studied. Of all lesions identified, 8% were cortical. FLAIR sequences are more sensitive to cortical and subcortical lesions in patients with active demyelination.

The role of the PTPRC (CD45) mutation in the development of multiple sclerosis in the North West region of the United Kingdom.

BACKGROUND: A point mutation in protein tyrosine phosphatase receptor, type c polypeptide (PTPRC) has been associated with familial multiple sclerosis. This CG mutation at position 77 of exon 4 results in altered expression of CD45 isoforms on immune cells. OBJECTIVE: To study the incidence of PTPRC mutations in subjects with multiple sclerosis in the North West region of the United Kingdom. METHODS: Affected and unaffected subjects from five pedigrees with familial multiple sclerosis, 330 non-familial cases of multiple sclerosis, and 197 controls were studied. Genomic DNA was amplified using CD45IE34 and CD45IE44 primers, digested with Mspl, and run on an agarose gel. Polymerase chain reaction products were sequenced to exclude any other mutations. RESULTS: No PTPRC exon 4 genomic mutations were seen in any of the five families. In the non-familial cases the incidence of mutation was 4.1% in 197 controls and 5.1% in 330 multiple sclerosis patients. No significant association was found in this study with this mutation and disease susceptibility, sex, or an extended disability scale score of < 5.5. CONCLUSIONS: This candidate does not appear to influence the development of familial multiple sclerosis in this population. The negative result could arise from a type II error owing to the number of families and non-familial cases screened. Alternatively it might suggest that the contribution of the PTPRC mutation depends upon the genetic background.

The glutathione S-transferases: polymerase chain reaction studies on the frequency of the GSTM1 0 genotype in patients with pituitary adenomas.

The frequency of the GSTM1 0 polymorphism at the glutathione S-transferase M1 locus has been determined in controls and patients with pituitary adenomas by using the polymerase chain reaction to amplify genomic DNA in the exon 4-5 region of the gene. The frequency of the genotype in patients with prolactinomas, non-functional adenomas, corticotrophinomas and somatotrophinomas varied between 52-67% compared with 44% in the controls. In the patients with prolactinomas the frequency of the genotype (67%) was significantly greater than in controls with odds ratio analysis indicating that GSTM1 0 individuals have a 2.56-fold greater risk of developing this adenoma.

Clinical and genetic changes in a case of a Cushing's carcinoma.

A 30-year-old presented in 1984 with a clinically nonfunctional tumour which subsequently developed into a metastatic corticotrophinoma from which he died despite surgery in 1984, 1986 and 1991 and external radiotherapy in 1986. Molecular genetic analysis of tumour and metastatic tissue revealed loss of heterozygosity at loci on the autosomes 1p, 3p, 10q26, 11q13 and 22q12. Tissue taken at surgery in 1986 also revealed positive cytoplasmic immunostaining for p53 protein. No such staining was evident in tissue taken at first surgery in 1984. Further analysis of invasive pituitary adenomas may reveal loci associated with such behaviour, enabling better prediction of subsequent clinical outcome than is possible using standard histological techniques, and delivery of early, aggressive treatment to those tumours which show molecular markers associated with a poor prognosis.

Susceptibility and outcome in MS: associations with polymorphisms in pigmentation-related genes.

Multiple sclerosis (MS) risk is determined by environment and genes. The authors investigated in 419 cases and 422 controls if polymorphism in the vitamin D receptor (VDR), melanocortin-1 receptor (MC1R), and tyrosinase (TYR) genes is linked with MS risk and outcome. VDR ff was associated with reduced (odds ratio [OR] = 0.59) and MC1R His294-encoding alleles with increased (OR = 2.21) risk. MC1R Glu84/Glu84 was linked with disability (OR = 5.65). These preliminary data suggest a role for these genes in MS pathogenesis.

Polymorphisms of apolipoprotein E; outcome and susceptibility in multiple sclerosis.

Allelic variants of the apolipoprotein E (APOE) gene influence the course of several neurological diseases. In multiple sclerosis the concentration of APOE in cerebrospinal fluid and its intrathecal synthesis is reduced. Specific isoforms of APOE may also be important and it has been suggested that possession of the epsilon4 allele may be associated with a more aggressive disease process. These data prompted us to re-examine, in a large group of patients with multiple sclerosis, the proposal that allelism in the apolipoprotein gene influences disease course. Genotypes were determined in a well-defined group of 370 unrelated Caucasians with clinically definite multiple sclerosis and in 159 healthy controls. Age at onset, sex, disease duration, disease subtype were recorded. Disability was measured using the Kurtzke expanded disability status score in patients with a disease duration of 10 years or greater. There was no significant difference in APOE allele or genotype frequencies between patients and controls, between disease subtypes or between genders. APOE genotype did not significantly influence age of onset, and no significant relationship between genotype, allele frequency and disease severity was found. This study suggests that individual APOE alleles or genotypes do not determine disease susceptibility or the clinical course of multiple sclerosis.