Methylenetetrahydrofolate reductase gene variants and antipsychotic-induced weight gain and metabolic disturbances

Weight gain and metabolic disturbances represent serious side-effects in antipsychotic (AP) treatment, particularly with clozapine and olanzapine. The methylenetetrahydrofolate reductase (MTHFR) gene is a key determinant in the folate metabolism and previous studies reported a significant effect on AP-induced weight gain and related metabolic abnormalities. Thus, we investigated MTHFR gene variants and changes in several important metabolic parameters in AP-treated patients. In this study, two functional MTHFR polymorphisms, rs1801133 (C677T) and rs1801131 (A1298C), were investigated for changes in weight and metabolic parameters. Genotypic associations were evaluated in a large population (n = 347 including 66 first episode psychosis, FEP patients) treated mostly with clozapine and olanzapine. We did not detect any genotypic association with weight changes (p > 0.05) in our total sample and in the sample refined for ancestry and medication. In our allelic analyses, we observed a trend for the 677-C allele to be associated with weight gain in the total sample (p = 0.03). This effect appeared to be driven by the FEP patients where those carrying the C-allele gained, on average, twice as much weight. Exploratory analyses revealed a significant association between the C677T and the A1298C polymorphism with HDL cholesterol serum levels in patients (p = 0.031). Overall we did not detect a major effect of two functional MTHFR gene variants and AP-induced weight gain. However, our findings suggest an effect of the C677T polymorphism in FEP patients and changes in weight and cholesterol levels. Further investigations in a larger sample are required.

Association study of MDR1 and 5-HT2C genetic polymorphisms and antipsychotic-induced metabolic disturbances in female patients with schizophrenia

The objective of this study was to determine the association of 5-HT2C (serotonin 2C receptor) and MDR1 (multidrug resistant protein) genetic polymorphisms and antipsychotic-induced metabolic abnormalities among female patients with DSM IV schizophrenia spectrum disorders. We have previously reported the associations of -759CT 5-HT2C and G2677T and C3435T MDR1 genetic polymorphisms and olanzapine/risperidone-induced weight gain in a similar sample of patients. Here, we included a total of 101 previously non-medicated female patients treated with olanzapine/risperidone over a 3-month period. The variables analyzed included fasting glucose, total cholesterol, low-density lipoprotein, high-density lipoprotein and triglyceride levels in blood, blood pressure and waist circumferences. We observed significant association of -759T 5-HT2C genetic variant and greater increase in waist circumference (P=0.03), fasting glucose level (P=0.046) and triglyceride level (P=0.045) in blood after a 3-month period. The 2677T and 3435T MDR1 genetic variants were significantly associated with the greater increase in fasting glucose level in blood when patients were using olanzapine (P<0.001 and P=0.028, respectively). Our data indicate a possible influence of -759CT 5-HT2C and MDR1 G2677T and C3435T MDR1 genetic polymorphisms on the development of metabolic abnormalities among female patients treated with olanzapine/risperidone.

Clinical variability of CMS-EA (congenital myasthenic syndrome with episodic apnea) due to identical CHAT mutations in two infants

Congenital myasthenic syndromes (CMS) result from mutations in various synapse-associated genes. Mutations in the choline acetyltransferase (CHAT) gene cause a presynaptic CMS associated with episodic apnea (CMS-EA). We present two unrelated Croatian children affected by CMS-EA. Beside other clinical findings characteristic for CMS, both patients manifested intermittent apneas since early infancy. Whereas the course of disease is mild in the female patient (patient 2), the male patient (patient 1) experienced recurrent and severe episodes of apnea despite adequate treatment with AChE-inhibitors and shows a global developmental delay with delayed myelination and signs of hypoxic-ischemic injury in brain imaging. Interestingly, sequencing of the CHAT gene revealed identical, compound heterozygous mutations S694C and T354M in both children. These findings are in line with a remarkable clinical heterogeneity observed in patients with CHAT mutations and emphasize the potential role of apneic crises for the development of secondary hypoxic brain damage and psychomotor retardation.

Apolipoprotein E polymorphism and serum concentration in Alzheimer's disease in nine European centres: the ApoEurope study. ApoEurope group

As part of the ApoEurope Project, apolipoprotein E (apo E) common polymorphism and serum concentration were determined in 489 Alzheimer's disease patients and 429 controls. Patients and controls were recruited through nine centres in eight European countries. Age, sex ratios and education levels of both case and control populations were similar, although discrete differences appeared between centres. The prevalence of the epsilon4 allele was higher in Alzheimer's disease than in controls (increased by 140%), while serum apo E concentration was lower by 11.2% (p<0.001). In addition, serum total cholesterol and triglyceride concentrations were lower in Alzheimer's disease (p<0.001), while that of apo Al was not affected. The decrease in serum apo E concentration was not accounted for by the epsilon4 allele, age or gender, suggesting that apo E concentration might represent an additional risk factor for Alzheimer's disease, complementary and independent of the epsilon4 allele. Further analysis will be aimed at determining whether the quantitative link between apo E concentration and Alzheimer's disease occurs through the effect of apo E genotype on lipid parameters or by other mechanisms.

Association between deletion polymorphism of the angiotensin-converting enzyme gene and cerebral atherosclerosis

We investigated deletion polymorphism in the gene for angiotensin-converting enzyme in patients with angiographically verified cerebral atherosclerosis. Genotypes were determined by the polymerase chain reaction with oligonucleotide flanking of the polymorphic region of intron 16 of the angiotensin-converting enzyme gene. Results of angiotensin-converting enzyme genotyping showed 46% of 50 studied patients to be homozygous for the DD allele, whose prevalence was significantly increased as compared with a group of controls without atherosclerotic changes. In this control group, the following genotypes were observed (%): II = 24, ID = 52 and DD = 24. The frequency of the I and D alleles in the group of patients with cerebral atherosclerosis was 0.28 and 0.72, respectively, whereas in the group without atherosclerosis it was 0.50 for both. Furthermore, in the present study, the DD genotype was associated with a high level of serum angiotensin-converting enzyme activity, total and LDL-cholesterol and triacylglycerol. A newly established association between DD genotype and cerebral atherosclerosis, detected even in our small group, supports the view that angiotensin-converting enzyme polymorphism might be indicative of the development of cerebral atherosclerosis.

Apolipoprotein E phenotypes and genotypes as determined by polymerase chain reaction using allele-specific oligonucleotide probes and the amplification refractory mutation system in children with insulin-dependent diabetes mellitus

The frequency of apolipoprotein E (apo E) phenotypes and genotypes due to allelic variation at amino acids 112 and 158 was analysed in 50 children with type I diabetes. Phenotypes were determined by isoelectric focusing and genotypes by the technique of polymerase chain reaction using allele-specific oligonucleotide probes (PCR/ASO) and the amplification refractory mutation system (ARMS). Discrepancies between phenotypes and genotypes as assigned by PCR/ASO were observed in 12 (24%) cases and by ARMS in eight (16%) cases. Results revealed the apo E3/3 genotype, as assigned by ARMS, to be the most frequent one (70%), followed by apo E3/4 in 16%, apo E2/2 in 2%, apo E2/3 in 8%, apo E2/4 in 2% and apo E4/4 in 2% of the cases. Apo E3/4 genotype and phenotype were more frequently present in the children with type I diabetes as compared with the diabetic adults previously reported on.