Acetylcholine receptor antibody in the diagnosis of myasthenia gravis

The acetylcholine receptor (AchR) antibody assay has a key role in the diagnosis of myasthenia gravis. In this article, the role of AchR antibody assay in the diagnosis of ocular and generalized myasthenia gravis is reviewed, and compared to standard means of diagnosing the disease by clinical and electrophysiological methods.

Acetylcholine receptor antibody in the diagnosis and management of myasthenia gravis

The relationship of acetylcholine receptor (AchR) antibodies to disease activity in myasthenia gravis (MG) is controversial. Some authors claim a direct correlation with disease activity and treatment, in particular plasmapheresis therapy, whereas others have commented on the poor overall correlation of antibody levels with clinical state. Antibody levels were examined in a population of MG patients and correlated with disease activity and response to treatment. Antibodies to skeletal muscle AchR were found in most patients with generalised MG (24/25) and in about half of the patients with purely ocular MG (6/10) and in neither of 2 patients with congenital MG. There was scant correlation with disease activity or response to treatment. It is concluded that the assay is more useful for diagnosis than for management of MG.

Detection of mRNA for nuclear receptor co-activators 1 and 3 in archival breast cancer tissue and surrounding stroma : a tissue expression study

Before the age of 75 years, approximately 10% of women will be diagnosed with breast cancer, one of the most common malignancies and a leading cause of death among women. The objective of this study was to determine if expression of the nuclear receptor coactivators 1 and 3 (NCoA1 and NCoA3) varied in breast cancer grades. RNA was extracted from 25 breast tumours and transcribed into cDNA which underwent semi-quantitative polymerase chain reaction, normalised using 18S. Analysis indicated that an expression change for NCoA1 in cancer grades and estrogen receptor alpha negative tissue (P= 0.028 and 0.001 respectively). NCoA1 expression increased in grade 3 and estrogen receptor alpha negative tumours, compared to controls. NCoA3 showed a similar, but not significant, trend in grade and a non-significant decrease in estrogen receptor alpha negative tissues. Expression of NCoA1 in late stage and estrogen receptor alpha negative breast tumours may have implications to breast cancer treatment, particularly in the area of manipulation of hormone signalling systems in advanced tumours.

A linkage and cross-sectional study of hypertension and obesity using a poly(A) Alu-repeat polymorphism at the glucagon receptor gene locus (17q25)

1. Previous glucagon receptor gene (GCGR) studies have shown a Gly40Ser mutation to be more prevalent in essential hypertension and to affect glucagon binding affinity to its receptor. An Alu-repeat poly(A) polymorphism colocalized to GCGR was used in the present study to test for association and linkage in hypertension as well as association in obesity development. 2. Using a cross-sectional approach, 85 hypertensives and 95 normotensives were genotyped using polymerase chain reaction primers flanking the Alu-repeat. Both hypertensive and normotensive populations were subdivided into lean and obese categories based on body mass index (BMI) to determine involvement of this variant in obesity. For the linkage study, 89 Australian Caucasian hypertension affected sibships (174 sibpairs) were genotyped and the results were analysed using GENE-HUNTER, Mapmaker Sibs, ERPA and SPLINK (all freely available from http://linlkage.rockefeller. edu/soft/list.html). 3. Cross-sectional results for both hypertension and obesity were analysed using Chi-squared and Monte Carlo analyses. Results did not show an association of this variant with either hypertension (χ2 = 6.9, P = 0.14; Monte Carlo χ2 = 7.0, P = 0.11; n = 5000) or obesity (χ2 = 3.3, P = 0.35; Monte Carlo χ2 = 3.26, P = 0.34; n = 5000). In addition, results from the linkage study using hypertensive sib-pairs did not indicate linkage of the poly(A) repent with hypertension. Hence, results did not indicate a role far the Alu-repeat in either hypertension or obesity. However, as the heterozygosity of this poly(A) repeat is low (35%), a larger number of hypertensive sib-pairs may be required to draw definitive conclusions.

Association of a low density lipoprotein receptor microsatellite variant with obesity

OBJECTIVE To determine whether a microsatellite polymorphism located towards the 3' end of the low density lipoprotein receptor gene (LDLR) is associated with obesity. DESIGN A cross-sectional case-control study. SUBJECTS One hundred and seven obese individuals, defined as a body mass index (BMI) ≤ 26 kg/m2, and 163 lean individuals, defined as a BMI < 26 kg/m2. MEASUREMENTS BMI, blood pressure, serum lipids, alleles of LDLR microsatellite (106 bp, 108 bp and 112 bp). RESULTS There was a significant association between variants of the LDLR microsatellite and obesity, in the overall tested population, due to a contributing effect in females (χ2 = 12.3, P = 0.002), but not in males (χ2 = 0.3, P = 0.87). In females, individuals with the 106 bp allele were more likely to be lean, while individuals with the 112 bp and/or 108 bp alleles tended to be obese. CONCLUSIONS These results suggest that in females, LDLR may play a role in the development of obesity.

Association of a RFLP for the insulin receptor gene, but not insulin, with essential hypertension

Insulin has cardiovascular actions and patients with essential hypertension display insulin resistance. A cross-sectional study of the R1 RFLP of the insulin receptor gene (INSR) was carried out in 67 hypertensive (HT) and 75 normotensive (NT) subjects whose parents had a similar blood pressure status at age ≥50. The frequency of the minor (+) allele was 0.31 in HTs and 0.44 in NTs, and the difference between observed alleles in all subjects in each group was significant (χ2 = 4.8, P<0.05). Allele frequencies of a BglI RFLP of the insulin gene, however, did not differ between the HT and NT groups. The data thus provide evidence in favour of an association of HT with a polymorphism at the INSR locus (19p 13.3-13.2), so implicating this locus, and possibly a genetic variant of the insulin receptor itself, in HT.

Non-linkage of insulin receptor locus with essential hypertension in an affected pedigree

A recent cross-sectional study has demonstrated a significant association of the R1 RsaI restriction fragment length polymorphism of the insulin receptor gene (INSR) with human essential hypertension. In the present study, an alternative approach, involving linkage analysis, was carried out using 8 hypertensive families with 5 or more affected members. Five of the families were found to be informative and in one of these pedigrees a conclusion of non-linkage of INSR and hypertension could be made on the basis of an obligate recombinant in one generation which yielded a Lod score of - ∞ at a recombination fraction (θ) of zero. In another family, the largest studied, a positive Lod score was obtained at θ = 0, but this was below the level required for a conclusion of linkage. Lod score at θ = 0 for a marker at the insulin locus in this family was negative. The present study has thus demonstrated one pedigree in which hypertension is not linked to the insulin receptor locus.

Association of HincII RFLP of low density lipoprotein receptor gene with obesity in essential hypertensives

Obese (BMI ≥ 26 kg/m 2; n = 51) and lean (BMI <26 kg/m 2; n = 61) Caucasian patients with severe, familial essential hypertension, were compared with respect to genotype and allele frequencies of a HincII RFLP of the low density lipoprotein receptor gene (LDLR). A similar analysis was performed in obese (n = 28) and lean (n = 68) normotensives. A significant association of the C allele of the T→C variant responsible for this RFLP was seen with obesity (χ 2 = 4.6, P = 0.029) in the hypertensive, but not in the normotensive, group (odds ratio = 3.0 for the CC genotype and 2.7 for CT). Furthermore, BMI tracked with genotypes of this allele in the hypertensives (P = 0.046). No significant genotypic relationship was apparent for plasma lipids. Significant linkage disequilibrium was, moreover, noted between the HincII RFLP and an ApaLI RFLP (χ 2 = 33, P<0.0005) that has previously shown even stronger association with obesity (odds ratio 19.6 for cases homozygous for the susceptibility allele and 15.2 for het-erozygotes). The present study therefore adds to our previous evidence implicating LDLR as a locus for obesity in patients with essential hypertension.

Association and linkage analyses of restriction fragment length polymorphisms for the human renin and antithrombin III genes in essential hypertension

Essential hypertension is a highly hereditable disorder in which genetic influences predominate over environmental factors. The molecular genetic profiles which predispose to essential hypertension are not known. In rats with genetic hypertension, there is some recent evidence pointing to linkage of renin gene alleles with blood pressure. The genes for renin and antithrombin III belong to a conserved synteny group which, in humans, spans the q21.3-32.3 region of chromosome I and, in rats, is linkage group X on chromosome 13. The present study examined the association of particular human renin gene (REN) and antithrombin III gene (AT3) polymorphisms with essential hypertension by comparing the frequency of specific alleles for each of these genes in 50 hypertensive offspring of hypertensive parents and 91 normotensive offspring of normotensive parents. In addition, linkage relationships were examined in hypertensive pedigrees with multiple affected individuals. Alleles of a REN HindIII restriction fragment length polymorphism (RFLP) were detected using a genomic clone, λHR5, to probe Southern blots of HindIII-cut leucocyte DNA, and those for an AT3 Pstl RFLP were detected by phATIII 113 complementary DNA probe. The frequencies of each REN allele in the hypertensive group were 0.76 and 0.24 compared with 0.74 and 0.26 in the normotensive group. For AT3, hypertensive allele frequencies were 0.49 and 0.51 compared with normotensive values of 0.54 and 0.46. These differences were not significant by χ2 analysis (P > 0.2). Linkage analysis of a family (data from 16 family members, 10 of whom were hypertensive), informative for both markers, without an age-of-onset correction, and assuming dominant inheritance of hypertension, complete penetrance and a disease frequency of 20%, did not indicate linkage of REN with hypertension, but gave a positive, although not significant, logarithm of the odds for linkage score of 0.784 at a recombination fraction of 0 for AT3 linkage to hypertension. In conclusion, the present study could find no evidence for an association of a REN HindIII RFLP with essential hypertension or for a linkage of the locus defined by this RFLP in a family segregating for hypertension. In the case of an AT3 Pstl RFLP, although association analysis was negative, linkage analysis suggested possible involvement (odds of 6:1 in favour) of a gene located near the 1q23 locus with hypertension in one informative family.

Evidence for allelic association of the dopamine β-hydroxylase gene (DBH) with susceptibility to typical migraine

Migraine is a debilitating neurological disorder characterized by recurrent attacks of severe headache. The disorder is highly prevalent, affecting approximately 12% of Caucasian populations. It is well known that migraine has a strong genetic component, although the type and number of genes involved is not yet clear. However, the calcium channel gene, CACNA1A, on chromosome 19 contains mutations responsible for familial hemiplegic migraine, a rare and severe subtype of migraine. There is also evidence to suggest that serotonin- and dopamine-related genes may be involved in the pathogenesis of migraine. This study employed a linkage and association approach to investigate neurotransmitter-related migraine candidate genes. Polymorphisms within the dopamine beta-hydroxylase (DBH) gene, serotonin transporter gene (SERT), and dopamine receptor gene (DRD2) were tested in 177 unrelated Caucasian migraineurs and 182 control individuals. In addition, an independent sample of 82 families affected with migraine was examined. Unrelated case-control association analysis of a DBH intragenic dinucleotide polymorphism indicated altered allelic distribution between migraine and control groups (L2=16.53, P=0.019). Furthermore, the transmission/disequilibrium test, which was implemented on the family data, also indicated distortion of allele transmission for the same DBH marker (L2=4.44, P=0.035). Together, these results provide evidence for allelic association of the DBH gene with typical migraine susceptibility (Fisher's combined P value=0.006) and indicate that further research into the role of the DBH gene in the etiology of migraine is warranted.

An androgen receptor mutation in the MDA-MB-453 cell line model of molecular apocrine breast cancer compromises receptor activity

Recent evidence indicates that the estrogen receptor-a-negative, androgen receptor (AR)- positive molecular apocrine subtype of breast cancer is driven by AR signaling. The MDA-MB-453 cell line is the prototypical model of this breast cancer subtype; its proliferation is stimulated by androgens such as 5a-dihydrotestosterone (DHT) but inhibited by the progestin medroxyprogesterone acetate (MPA) via AR-mediated mechanisms. We report here that the AR gene in MDAMB- 453 cells contains a G-T transversion in exon 7, resulting in a receptor variant with a glutamine to histidine substitution at amino acid 865 (Q865H) in the ligand binding domain. Compared with wild-type AR, the Q865H variant exhibited reduced sensitivity to DHT and MPA in transactivation assays in MDA-MB-453 and PC-3 cells but did not respond to non-androgenic ligands or receptor antagonists. Ligand binding, molecular modeling, mammalian two-hybrid and immunoblot assays revealed effects of the Q865H mutation on ligand dissociation, AR intramolecular interactions, and receptor stability. Microarray expression profiling demonstrated that DHT and MPA regulate distinct transcriptional programs in MDA-MB-453 cells. Gene Set Enrichment Analysis revealed that DHT- but not MPA-regulated genes were associated with estrogen-responsive transcriptomes from MCF-7 cells and the Wnt signaling pathway. These findings suggest that the divergent proliferative responses of MDA-MB-453 cells to DHT and MPA result from the different genetic programs elicited by these two ligands through the AR-Q865H variant. This work highlights the necessity to characterize additional models of molecular apocrine breast cancer to determine the precise role of AR signaling in this breast cancer subtype. Endocrine-Related Cancer (2012) 19 599–613

Endophenotype profiles of MTHFR and ACE gene polymorphisms in migraine susceptibility

Background Migraine is a debilitating neurological disorder affecting approximately 12% of the Caucasian population. There are two main sub-types of migraine, migraine without aura (MO) and migraine with aura (MA). Migraine exhibits varied phenotypic expression with sufferers experiencing a range of neurological and other symptoms. It is likely that multiple susceptibility genes play a role in this varied phenotypic expression, thus investigation of genotype-phenotype relationships may provide valuable insights into the role of susceptibility genes in this disorder. Methods This study investigated the links between migraine susceptibility genes, methylenetetrahydrofolate reductase (MTHFR) and angiotensin converting enzyme (ACE), and clinical manifestation through statistical analyses. Results The result showed that for the MTHFR genotypes, there was a statistically significant correlation with the TT homozygous genotype and visual disturbances, unilateral head pain and physical activity discomforts. It was also found that bilateral head pain was associated with the male gender. Conclusion From these study results, it is plausible to state that MTHFR genotypes affect the phenotypic expression of migraine disease manifestation.

Expression pattern of the cannabinoid receptor genes in the frontal cortex of mood disorder patients and mice selectively bred for high and low fear

Although the endocannabinoid system (ECS) has been implicated in brain development and various psychiatric disorders, precise mechanisms of the ECS on mood and anxiety disorders remain unclear. Here, we have investigated developmental and disease-related expression pattern of the cannabinoid receptor 1 (CB1) and the cannabinoid receptor 2 (CB2) genes in the dorsolateral prefrontal cortex (PFC) of humans. Using mice selectively bred for high and low fear, we further investigated potential association between fear memory and the cannabinoid receptor expression in the brain. The CB1, not the CB2, mRNA levels in the PFC gradually decrease during postnatal development ranging in age from birth to 50 years (r 2 > 0.6 & adj. p < 0.05). The CB1 levels in the PFC of major depression patients were higher when compared to the age-matched controls (adj. p < 0.05). In mice, the CB1, not the CB2, levels in the PFC were positively correlated with freezing behavior in classical fear conditioning (p < 0.05). These results suggest that the CB1 in the PFC may play a significant role in regulating mood and anxiety symptoms. Our study demonstrates the advantage of utilizing data from postmortem brain tissue and a mouse model of fear to enhance our understanding of the role of the cannabinoid receptors in mood and anxiety disorders

Receptor tyrosine kinases and their activation in melanoma

Receptor tyrosine kinases (RTKs) and their downstream signalling pathways have long been hypothesized to play key roles in melanoma development. A decade ago, evidence was derived largely from animal models, RTK expression studies and detection of activated RAS isoforms in a small fraction of melanomas. Predictions that overexpression of specific RTKs implied increased kinase activity and that some RTKs would show activating mutations in melanoma were largely untested. However, technological advances including rapid gene sequencing, siRNA methods and phospho-RTK arrays now give a more complete picture. Mutated forms of RTK genes including KIT, ERBB4, the EPH and FGFR families and others are known in melanoma. Additional over- or underexpressed RTKs and also protein tyrosine phosphatases (PTPs) have been reported, and activities measured. Complex interactions between RTKs and PTPs are implicated in the abnormal signalling driving aberrant growth and survival in malignant melanocytes, and indeed in normal melanocytic signalling including the response to ultraviolet radiation. Kinases are considered druggable targets, so characterization of global RTK activity in melanoma should assist the rational development of tyrosine kinase inhibitors for clinical use. © 2011 John Wiley & Sons A/S.