Association Study of Fat-mass and Obesity-associated Gene and Body Mass Index in Japanese Patients with Schizophrenia and Healthy Subjects

Search for Possible Associations of FTO Gene Polymorphic Variants with Metabolic Syndrome, Obesity and Body Mass Index in Schizophrenia Patients

Purpose

Metabolic syndrome (MetS) is characterized by abdominal obesity, hyperglycaemia, dyslipidaemia and hypertension. FTO gene has been implicated in the pathogenesis of obesity, but the available scientific data concerning their relationship to antipsychotic drug-induced obesity and metabolic syndrome is still incomplete and inconsistent, which indicates that continuing the investigation of this gene’s role is necessary.

Patients and Methods

In the present study, 517 patients with schizophrenia underwent antipsychotic drug treatment, and two groups were identified: patients with MetS and without MetS. Genotyping of 6 SNPs in the FTO gene was performed, and the results analyzed using R-programme.

Results

We performed a statistical analysis to identify possible associations of the frequencies of genotypes and alleles of the studied polymorphisms with the presence of metabolic syndrome in schizophrenia patients, with the presence of abdominal obesity, and with an increased body mass index. The rs7185735 polymorphism did not meet the Hardy-Weinberg criterion and was excluded. After correcting for differences in age, gender and duration of illnesses, none of the variants was shown to be related to metabolic syndrome or abdominal obesity, but rs9939609, rs1421085, rs3751812 and rs8050136 were associated with body mass index.

Conclusion

The present study provides additional support for these SNP’s roles as a pharmacogenetic biomarker that may become useful in the framework of the personalized medicine approach.

Serum Prolactin and Bone Mineral Density in Schizophrenia: A Systematic Review

The relationship between serum prolactin and bone mineral density (BMD) in schizophrenia is unclear. We conducted a literature review of databases from inception until December 2018 for cross-sectional, case-control, prospective and retrospective studies analyzing correlations between serum prolactin and BMD measured using dual energy X-ray absorptiometry or quantitative ultrasound at any skeletal site in people with schizophrenia. Data was summarized with a best evidence synthesis. This review identified 15 studies (1 longitudinal study, 10 cross-sectional and 4 case-control studies; 1,360 individuals with a psychotic disorder; mean age 45.1 ± 9.4 [standard deviation] years, female 742 [54.6%], mean illness duration 17.7 ± 11.3 years) assessing the relationship between serum prolactin and BMD in schizophrenia. There was a statistically significant inverse correlation between serum prolactin and BMD identified in eight of the studies (53% of all studies), suggesting mixed evidence for an association between serum prolactin and BMD. Of those studies which identified a significant inverse correlation between serum prolactin and BMD (n = 5), 152 (52.1%) of patients were treated with prolactin raising antipsychotics, compared to 197 (48.1%) of patients in those studies which did not identify a significant correlation between prolactin and BMD. Available studies cannot resolve the link between excess prolactin and reduced BMD in schizophrenia. Future studies should be longitudinal in design and combine measures of serum prolactin along with other risk factors for reduced BMD such as smoking and vitamin D and sex hormone levels in assessing the relationship between prolactin and BMD in schizophrenia.

Fat-mass and obesity-associated gene polymorphisms and weight gain after risperidone treatment in first episode schizophrenia

Background

Obesity induced by antipsychotics severely increases the risk of many diseases and significantly reduces quality of life. Genome Wide Association Studies has identified fat-mass and obesity-associated (FTO) gene associated with obesity. The relationship between the FTO gene and drug-induced obesity is unclear.

Method

Two hundred and fifty drug naïve, Chinese Han patients with first-episode schizophrenia were enrolled in the study, and genotyped for four single nucleotide polymorphisms (SNPs rs9939609, rs8050136, rs1421085 and rs9930506) by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequencing. Body weight and body mass index (BMI) were measured at baseline and six months after risperidone treatment.

Results

At baseline, body weight and BMI of TT homozygotes were lower than those of A allele carriers in rs9939609; body weight of AA homozygotes was higher than those of G allele carriers in rs9930506 (p’s < 0.05). After 6 months of risperidone treatment, body weight and BMI of TT homozygotes were lower than those of A allele carriers in rs9939609 (p’s <0.01); body weight and BMI of CC homozygotes were lower than those of A allele carriers in rs8050136 (p’s < 0.05); body weight of AA homozygotes was higher than those of G allele carriers in rs9930506 (p’s < 0.05). After controlling for age, gender, age of illness onset, disease duration, weight at baseline and education, weight gain of TT homozygotes at 6 months remained to be lower than those of A allele carriers in rs9939609 (p < 0.01); weight gain of CC homozygotes at 6 months was lower than those of A allele carriers in rs8050136 (p = 0.01). Stepwise multiple regression analysis suggested that, among 4 SNPs, rs9939609 was the strongest predictor of weight gain after 6 months of risperidone treatment (p = 0.001).

Conclusions

The FTO gene polymorphisms, especially rs9939609, seem to be related to weight gain after risperidone treatment in Chinese Han patients with first episode schizophrenia.