PSMD9 gene in the NIDDM2 locus is linked to type 2 diabetes in Italians

A Drosophila model of diabetic neuropathy reveals a role of proteasome activity in the glia

Diabetic peripheral neuropathy (DPN) is the most common chronic, progressive complication of diabetes mellitus. The main symptom is sensory loss; the molecular mechanisms are not fully understood. We found that Drosophila fed a high-sugar diet, which induces diabetes-like phenotypes, exhibit impairment of noxious heat avoidance. The impairment of heat avoidance was associated with shrinkage of the leg neurons expressing the Drosophila transient receptor potential channel Painless. Using a candidate genetic screening approach, we identified proteasome modulator 9 as one of the modulators of impairment of heat avoidance. We further showed that proteasome inhibition in the glia reversed the impairment of noxious heat avoidance, and heat-shock proteins and endolysosomal trafficking in the glia mediated the effect of proteasome inhibition. Our results establish Drosophila as a useful system for exploring molecular mechanisms of diet-induced peripheral neuropathy and propose that the glial proteasome is one of the candidate therapeutic targets for DPN.

The potential of integrating human and mouse discovery platforms to advance our understanding of cardiometabolic diseases

Cardiometabolic diseases encompass a range of interrelated conditions that arise from underlying metabolic perturbations precipitated by genetic, environmental, and lifestyle factors. While obesity, dyslipidaemia, smoking, and insulin resistance are major risk factors for cardiometabolic diseases, individuals still present in the absence of such traditional risk factors, making it difficult to determine those at greatest risk of disease. Thus, it is crucial to elucidate the genetic, environmental, and molecular underpinnings to better understand, diagnose, and treat cardiometabolic diseases. Much of this information can be garnered using systems genetics, which takes population-based approaches to investigate how genetic variance contributes to complex traits. Despite the important advances made by human genome-wide association studies (GWAS) in this space, corroboration of these findings has been hampered by limitations including the inability to control environmental influence, limited access to pertinent metabolic tissues, and often, poor classification of diseases or phenotypes. A complementary approach to human GWAS is the utilisation of model systems such as genetically diverse mouse panels to study natural genetic and phenotypic variation in a controlled environment. Here, we review mouse genetic reference panels and the opportunities they provide for the study of cardiometabolic diseases and related traits. We discuss how the post-GWAS era has prompted a shift in focus from discovery of novel genetic variants to understanding gene function. Finally, we highlight key advantages and challenges of integrating complementary genetic and multi-omics data from human and mouse populations to advance biological discovery.

Implication of Melanocortin Receptor Genes in the Familial Comorbidity of Type 2 Diabetes and Depression

The melanocortin receptors are G-protein-coupled receptors, which are essential components of the hypothalamic–pituitary–adrenal axis, and they mediate the actions of melanocortins (melanocyte-stimulating hormones: α-MSH, β-MSH, and γ-MSH) as well as the adrenocorticotropin hormone (ACTH) in skin pigmentation, adrenal steroidogenesis, and stress response. Three melanocortin receptor genes (MC1R, MC2R, and MC5R) contribute to the risk of major depressive disorder (MDD), and one melanocortin receptor gene (MC4R) contributes to the risk of type 2 diabetes (T2D). MDD increases T2D risk in drug-naïve patients; thus, MDD and T2D commonly coexist. The five melanocortin receptor genes might confer risk for both disorders. However, they have never been investigated jointly to evaluate their potential contributing roles in the MDD-T2D comorbidity, specifically within families. In 212 Italian families with T2D and MDD, we tested 11 single nucleotide polymorphisms (SNPs) in the MC1R gene, 9 SNPs in MC2R, 3 SNPs in MC3R, 4 SNPs in MC4R, and 2 SNPs in MC5R. The testing used 2-point parametric linkage and linkage disequilibrium (LD) (i.e., association) analysis with four models (dominant with complete penetrance (D1), dominant with incomplete penetrance (D2), recessive with complete penetrance (R1), and recessive with incomplete penetrance (R2)). We detected significant (p ≤ 0.05) linkage and/or LD (i.e., association) to/with MDD for one SNP in MC2R (rs111734014) and one SNP in MC5R (rs2236700), and to/with T2D for three SNPs in MC1R (rs1805007 and rs201192930, and rs2228479), one SNP in MC2R (rs104894660), two SNPs in MC3R (rs3746619 and rs3827103), and one SNP in MC4R genes (Chr18-60372302). The linkage/LD/association was significant across different linkage patterns and different modes of inheritance. All reported variants are novel in MDD and T2D. This is the first study to report risk variants in MC1R, MC2R, and MC3R genes in T2D. MC2R and MC5R genes are replicated in MDD, with one novel variant each. Within our dataset, only the MC2R gene appears to confer risk for both MDD and T2D, albeit with different risk variants. To further clarity the role of the melanocortin receptor genes in MDD-T2D, these findings should be sought among other ethnicities as well.

Ubiquitin-proteasome system in diabetic retinopathy

Diabetic retinopathy (DR) is the most common complication of diabetes, being the most prevalent reason for blindness among the working-age population in the developed world. Despite constant improvement of understanding of the pathogenesis of DR, identification of novel biomarkers of DR is needed for improvement of patient risk stratification and development of novel prevention and therapeutic approaches. The ubiquitin-proteasome system (UPS) is the primary protein quality control system responsible for recognizing and degrading of damaged proteins. This review aims to summarize literature data on modifications of UPS in diabetes and DR. First, we briefly review the structure and functions of UPS in physiological conditions. We then describe how UPS is involved in the development and progression of diabetes and touch upon the association of UPS genetic factors with diabetes and its complications. Further, we focused on the effect of diabetes-induced hyperglycemia, oxidative stress and hypoxia on UPS functioning, with examples of studies on DR. In other sections, we discussed the association of several other mechanisms of DR (endoplasmic reticulum stress, neurodegeneration etc) with UPS modifications. Finally, UPS-affecting drugs and remedies are reviewed. This review highlights UPS as a promising target for the development of therapies for DR prevention and treatment and identifies gaps in existing knowledge and possible future study directions.

Mechanisms Underlying the Comorbidity of Schizophrenia and Type 2 Diabetes Mellitus

The mortality rate of patients with schizophrenia is high, and life expectancy is shorter by 10 to 20 years. Metabolic abnormalities including type 2 diabetes mellitus (T2DM) are among the main reasons. The prevalence of T2DM in patients with schizophrenia may be epidemiologically frequent because antipsychotics induce weight gain as a side effect and the cognitive dysfunction of patients with schizophrenia relates to a disordered lifestyle, poor diet, and low socioeconomic status. Apart from these common risk factors and risk factors unique to schizophrenia, accumulating evidence suggests the existence of common susceptibility genes between schizophrenia and T2DM. Functional proteins translated from common genetic susceptibility genes are known to regulate neuronal development in the brain and insulin in the pancreas through several common cascades. In this review, we discuss common susceptibility genes, functional cascades, and the relationship between schizophrenia and T2DM. Many genetic and epidemiological studies have reliably associated the comorbidity of schizophrenia and T2DM, and it is probably safe to think that common cascades and mechanisms suspected from common genes' functions are related to the onset of both schizophrenia and T2DM. On the other hand, even when genetic analyses are performed on a relatively large number of comorbid patients, the results are sometimes inconsistent, and susceptibility genes may carry only a low or moderate risk. We anticipate future directions in this field.

Co-shared genetics and possible risk gene pathway partially explain the comorbidity of schizophrenia, major depressive disorder, type 2 diabetes, and metabolic syndrome

Schizophrenia (SCZ) and major depressive disorder (MDD) in treatment-naive patients are associated with increased risk for type 2 diabetes (T2D) and metabolic syndrome (MetS). SCZ, MDD, T2D, and MetS are often comorbid and their comorbidity increases cardiovascular risk: Some risk genes are likely co-shared by them. For instance, transcription factor 7-like 2 (TCF7L2) and proteasome 26S subunit, non-ATPase 9 (PSMD9) are two genes independently reported as contributing to T2D and SCZ, and PSMD9 to MDD as well. However, there are scarce data on the shared genetic risk among SCZ, MDD, T2D, and/or MetS. Here, we briefly describe T2D, MetS, SCZ, and MDD and their genetic architecture. Next, we report separately about the comorbidity of SCZ and MDD with T2D and MetS, and their respective genetic overlap. We propose a novel hypothesis that genes of the prolactin (PRL)-pathway may be implicated in the comorbidity of these disorders. The inherited predisposition of patients with SCZ and MDD to psychoneuroendocrine dysfunction may confer increased risk of T2D and MetS. We illustrate a strategy to identify risk variants in each disorder and in their comorbid psychoneuroendocrine and mental-metabolic dysfunctions, advocating for studies of genetically homogeneous and phenotype-rich families. The results will guide future studies of the shared predisposition and molecular genetics of new homogeneous endophenotypes of SCZ, MDD, and metabolic impairment.

An integrative systems genetic analysis of mammalian lipid metabolism

Dysregulation of lipid homeostasis is a precipitating event in the pathogenesis and progression of hepatosteatosis and metabolic syndrome. These conditions are highly prevalent in developed societies and currently have limited options for diagnostic and therapeutic intervention. Here, using a proteomic and lipidomic-wide systems genetic approach, we interrogated lipid regulatory networks in 107 genetically distinct mouse strains to reveal key insights into the control and network structure of mammalian lipid metabolism. These include the identification of plasma lipid signatures that predict pathological lipid abundance in the liver of mice and humans, defining subcellular localization and functionality of lipid-related proteins, and revealing functional protein and genetic variants that are predicted to modulate lipid abundance. Trans-omic analyses using these datasets facilitated the identification and validation of PSMD9 as a previously unknown lipid regulatory protein. Collectively, our study serves as a rich resource for probing mammalian lipid metabolism and provides opportunities for the discovery of therapeutic agents and biomarkers in the setting of hepatic lipotoxicity.

Dopamine-prolactin pathway potentially contributes to the schizophrenia and type 2 diabetes comorbidity

Schizophrenia (SCZ) and type 2 diabetes (T2D) are clinically associated, and common knowledge attributes this association to side effects of antipsychotic treatment. However, even drug-naive patients with SCZ are at increased risk for T2D. Dopamine dysfunction has a central role in SCZ. It is well-known that dopamine constitutively inhibits prolactin (PRL) secretion via the dopamine receptor 2 (DR2D). If dopamine is increased or if dopamine receptors hyperfunction, PRL may be reduced. During the first SCZ episode, low PRL levels are associated with worse symptoms. PRL is essential in human and social bonding, as well as it is implicated in glucose homeostasis. Dopamine dysfunction, beyond contributing to SCZ symptoms, may lead to altered appetite and T2D. To our knowledge, there are no studies of the genetics of the SCZ-T2D comorbidity focusing jointly on the dopamine and PRL pathway in the attempt to capture molecular heterogeneity correlated to possible disease manifestation heterogeneity. In this dopamine-PRL pathway-focused-hypothesis-driven review on the association of SCZ with T2D, we report a specific revision of what it is known about PRL and dopamine in relation to what we theorize is one of the missing links between the two disorders. We suggest that new studies are necessary to establish the genetic role of PRL and dopamine pathway in SCZ-T2D comorbidity.

T2D and Depression Risk Gene Proteasome Modulator 9 is Linked to Insomnia

Insomnia increases type-2 diabetes (T2D) risk. The 12q24 locus is linked to T2D, depression, bipolar disorder and anxiety. At the 12q24 locus, the Proteasome-Modulator 9 (PSMD9) single nucleotide polymorphisms (SNPs) rs74421874 [intervening sequence (IVS) 3+nt460-G>A], rs3825172 (IVS3+nt437-C>T) and rs14259 (E197G-A>G) are linked to: T2D, depression, anxiety, maturity-onset-diabetes-of the young 3/MODY3, obesity, waist circumference, hypertension, hypercholesterolemia, T2D-macrovascular disease, T2D-microvascular disease, T2D-neuropathy, T2D-carpal-tunnel syndrome, T2D-nephropathy, T2D-retinopathy and non-diabetic retinopathy. PSMD9 SNP rs1043307/rs14259 (E197G-A>G) plays a role in anti-depressant therapy response, depression and schizophrenia. We aimed at determining PSMD9 rs74421874/rs3825172/rs14259 SNPs potential linkage to primary insomnia and sleep hours in T2D families. We recruited 200 Italian T2D families phenotyping them for primary insomnia and sleep hours per night. PSMD9-T2D-risk SNPs rs74421874/rs3825172 and rs1043307/rs14259 were tested for linkage with insomnia and sleep hours. Non-parametric-linkage analysis, linkage-disequilibrium-model analysis, single-SNP analysis, cluster-based-parametric analysis, quantitative-trait and variant-component analysis were performed using Merlin software. To validate data, 1000 replicates were executed for the significant non-parametric data. PSMD9 rs74421874 (IVS3+nt460-G>A), rs3825172 (IVS3+nt437-C>T) and rs1043307/rs14259 (E197G-A>G) SNPs are linked to insomnia in our Italian families.

Proteasome modulator 9 gene SNPs, responsible for anti-depressant response, are in linkage with generalized anxiety disorder

Proteasome modulator 9 (PSMD9) gene single nucleotide polymorphism (SNP) rs1043307/rs2514259 (E197G) is associated with significant clinical response to the anti-depressant desipramine. PSMD9 SNP rs74421874 [intervening sequence (IVS) 3 + nt460 G>A], rs3825172 (IVS3 + nt437 C>T) and rs1043307/rs2514259 (E197G A>G) are all linked to type 2 diabetes (T2D), maturity-onset-diabetes-of the young 3 (MODY3), obesity and waist circumference, hypertension, hypercholesterolemia, T2D-macrovascular and T2D-microvascular disease, T2D-neuropathy, T2D-carpal tunnel syndrome, T2D-nephropathy, T2D-retinopathy, non-diabetic retinopathy and depression. PSMD9 rs149556654 rare SNP (N166S A>G) and the variant S143G A>G also contribute to T2D. PSMD9 is located in the chromosome 12q24 locus, which per se is in linkage with depression, bipolar disorder and anxiety. In the present study, we wanted to determine whether PSMD9 is linked to general anxiety disorder in Italian T2D families. Two-hundred Italian T2D families were phenotyped for generalized anxiety disorder, using the diagnostic criteria of DSM-IV. When the diagnosis was unavailable or unclear, the trait was reported as unknown. The 200 Italians families were tested for the PSMD9 T2D risk SNPs rs74421874 (IVS3 + nt460 G>A), rs3825172 (IVS3 +nt437 T>C) and for the T2D risk and anti-depressant response SNP rs1043307/rs2514259 (E197G A>G) for evidence of linkage with generalized anxiety disorder. Non-parametric linkage analysis was executed via Merlin software. One-thousand simulation tests were performed to exclude results due to random chance. In our study, the PSMD9 gene SNPs rs74421874, rs3825172, and rs1043307/rs2514259 result in linkage to generalized anxiety disorder. This is the first report describing PSMD9 gene SNPs in linkage to generalized anxiety disorder in T2D families.

Overweight condition and waist circumference and a candidate gene within the 12q24 locus

Aims

Obesity and obesity-associated phenotypes are linked to the chromosome12q24 locus, the non-insulin-dependent-diabetes 2 (NIDDM2) locus. The gene of proteasome modulator 9 (PSMD9) lies in the NIDDM2 region and is linked to type 2 diabetes (T2D), microvascular and macrovascular complications of T2D.

We aimed at studying whether the PSMD9 T2D risk single nucleotide polymorphisms (SNPs) IVS3+nt460, IVS3+nt437, and 197G are linked to obesity, overweight status and waist circumference in Italian T2D families.

Methods and results

We screened 200 Italians T2D siblings/families for PSMD9 variants. Using Merlin software, we performed non-parametric linkage analysis to test for linkage with obesity and overweight condition and variance component analysis to test for linkage with waist circumference in our T2D siblings/families dataset.

Our study shows that the PSMD9 SNPs IVS3+nt460, IVS3+nt437, and 197G are in linkage with overweight condition and waist circumference in Italians. The statistical power tests performed via simulations on real data confirm that the results are not due to random chance.

Conclusions

In summary, the linkage strategy using a homogeneous family/subject dataset can identify a gene contributing to a complex trait. PMSD9 may be at least one of the genes responsible for the linkage to obesity and obesity-associated phenotypes at the locus 12q24 in other populations.

Proteasome modulator 9 is linked to microvascular pathology of T2D

The locus 12q24 is linked to type 2 diabetes (T2D) and to changes in retinal vascular caliber in Caucasians. Proteasome Modulator 9 gene (PSMD9) lies in the 12q24 locus and is implicated in diabetes onset and in degradation of intracellular proteins in antigenic peptides in the immune response to antigen presentation by MHC class I cells. Within PSMD9, we reported a linkage to T2D and to MODY3 in Italian families. We recently demonstrated a linkage of the PSMD9 T2D risk SNPs with T2D-nephropathy, T2D-neuropathy, retinopathy, hypercholesterolemia, and macrovascular pathology. We aimed at studying the presence of the linkage signal of the PSMD9 T2D risk SNPs IVS3 + nt460, IVS3 + nt437, E197G to microvascular pathology associated to T2D in Italian siblings/families. We screened 200 T2D siblings/families for the PSMD9 above-mentioned variants and performed a parametric and non-parametric linkage study by Merlin software. Our results show significant LOD score in linkage with microvascular pathology for the PSMD9 SNPs studied using the non-parametric and parametric linkage analysis. The strongest signal is present under the recessive model. Our statistical power relies on the presence of T2D affected siblings, which represent an ideal dataset to identify linkage with a recessive disease model. Our simulation analysis confirms that the results are not due to random chance. In summary, the PSMD9 IVS3 + nt460, IVS3 + nt437, E197G SNPs are linked via the recessive model to microvascular pathology of T2D in Italians. A possible role of PSMD9 in microvascular pathology may be related to a causative pathogenetic role in inflammation as part of an autoimmune process.

Chromosome 15q21-22-related polymorphisms and haplotypes are associated with susceptibility to type-2 diabetic nonproliferative retinopathy

OBJECTIVE

Diabetic retinopathy (DR) is a microvascular complication of diabetes with a complex multifactorial pathogenesis. We aimed to investigate whether chromosome 15q21-22-related gene polymorphisms could be used as markers of DR susceptibility in type 2 diabetic (T2D) individuals.

METHODS

Individuals were divided into three groups: (1) T2D with nonproliferative DR (NPDR; n=102); (2) T2D with proliferative DR (PDR; n=72); (3) T2D without DR (n=573). Six single-nucleotide polymorphisms (SNPs) (rs7174997, rs3751624, rs8025011, rs17818837, rs2922220, and rs2414520) lying within chromosome 15q21-22 region were genotyped by using Illumina HumanHap550-Duo BeadChips. Genotypes/allelic frequencies and haplotypes for these polymorphisms in each group were compared.

RESULTS

The MYO5C related SNP (rs3751624)*A related genotype and allele are associated with higher susceptibilities to DR, including PDR and NPDR. The rs3751624*GG/AA+AG percentages in each group are (1) 75.5%/24.5%, (2) 73.6%/26.4%, and (3) 82.5%/17.5%. In contrast, the other five SNPs in each group were not significantly different. One haplotype (G-A-G-G-T-G) appears significantly different between T2D individuals with and without DR. Other haplotype distributions were not significantly different between each group.

CONCLUSION

The MYO5C related SNP (rs3751624)*A related genotype/allele and haplotype (G-A-G-G-T-G) might be associated with susceptibility for retinopathy in T2D individuals. Some chromosome 15q21-22* related genetic variations might contribute to the pathogenesis of DR.

Proteasome modulator 9 and carpal tunnel syndrome

Proteasome modulator 9 (PSMD9) is linked to type 2 diabetes (T2D). The author studied whether PSMD9 IVS3 + nt460 A > G, IVS3 + nt437 T > C and E197 are linked to carpal tunnel syndrome in T2D Italian families. Non-parametric linkage, linkage disequilibrium-based and independent SNPs-based linkage analyses were performed. The PSMD9 SNPs show linkage to carpal tunnel syndrome.

PSMD9 is linked to type 2 diabetes neuropathy

OBJECTIVE

Diabetic neuropathy, a long-term complication of type 2 diabetes (T2D), has a genetic inheritance component to its manifestation. We aimed at identifying whether the proteasome modulator 9 (PSMD9) gene responsible for linkage with T2D and maturity-onset diabetes of the young 3 in Italian families may play a role in the inheritance of diabetic neuropathy in T2D as well.

METHODS

We characterized the Italian families with T2D for presence and/or absence of diabetic neuropathy. The diabetic neuropathy is reported as unknown in all cases in which either the diagnosis was unclear or the data were not available for the subject studied. Thus, in our 200 Italian families, the data presence was less than 100%. We tested in the 200 Italians families for the presence of the linkage of the PSMD9 single nucleotide polymorphisms (SNPs) with diabetic neuropathy. The nonparametric as well as the parametric linkage analysis was performed by using the Merlin software; the LOD score and correspondent P value were calculated. For the significance and/or trends toward significance linkage score, 1000 replicates were performed to determine the empirical P value.

RESULTS

We report the linkage study of the PSMD9 SNPs [intervening sequence IVS3+nt460A/G, IVS3+nt437C/T and E197G] in Italian families with T2D neuropathy.

CONCLUSION

In summary, the PSMD9 gene SNPs studied contribute to the genetic risk of diabetic neuropathy in our Italian data set, showing statistical significance for an additive model-based inheritance.

Proteasome modulator 9 SNPs are linked to hypertension in type 2 diabetes families

Background

Chromosome 12q24 was recently associated with hypertension. Proteasome Modulator 9 (PSMD9) lies in the 12q24 locus and is in linkage with MODY3, type 2 diabetes (T2D), microvascular and macrovascular pathology, carpal tunnel syndrome, and hypercholesterolemia in Italian families.

Aims

Our goal was to determine whether PSMD9 is linked to elevated blood pressure/hypertension in T2D families.

Methods

We characterized the Italian T2D families' members for presence and/or absence of elevated blood pressure (≥ 130/80) and/or hypertension. The phenotypes were described as unknown in all cases in which the diagnosis was either unclear or the data were not available for the subject studied. We tested in the 200 Italians families for the presence of the linkage of the PSMD9 T2D risk single nucleotide polymorphisms (SNPs) IVS3+nt460 A > G, IVS3+nt437 T > C and E197G A > G with elevated blood pressure/hypertension. The non-parametric linkage analysis was performed for this qualitative phenotype by using the Merlin software; the Lod score and correspondent P-value were calculated. Parametric linkage analysis was also performed. For the significant linkage score, 1000 replicates were run to calculate the empirical P-value.

Results

The PSMD9 gene SNPs studied are in linkage with elevated blood pressure/hypertension in our Italian families.

Conclusions

We conclude that the PSMD9 gene and/or any variant in linkage disequilibrium with the SNPs studied contribute to the linkage to hypertension within our family dataset. This is the first report of PSMD9 linkage to hypertension within the 12q24 locus.

Proteasome modulator 9 gene is linked to diabetic and non-diabetic retinopathy in T2D

BACKGROUND

Diabetic retinopathy is a long-term complication of type 2 diabetes (T2D). Non-diabetic retinopathy may be present in T2D patients as well and non-T2D patients with hypertension and/or atherosclerosis. The aim of this study was to identify linkage of the proteasome modulator 9 (PSMD9) T2D risk variants IVS3+nt460, IVS3+nt437, E197G to diabetic retinopathy and retinopathy including also atherosclerotic or hypertensive retinopathy in Italian T2D families.

MATERIALS AND METHODS

A total of 126 siblings of our 200 T2D siblings/families were characterized for diabetic retinopathy or retinopathy. The clinical characterization is based on a fundus oculi exam and on fluorangiography of the participating subjects. Diabetic retinopathy includes both pre-proliferative and proliferative retinopathy. The common gene variants were directly amplified by PCR and by fluorescent-based automation. A parametric and non-parametric linkage study of the gene variants with diabetic retinopathy and retinopathy was then performed using Merlin software. Finally, 1000 simulation analyses were performed to test for the statistical power of the significant results (P-value ≤ 0.05).

RESULTS

This study shows a linkage of the PSMD9 IVS3+nt460 (rs74421874), IVS3+nt437 (rs3825172) and E197G (rs14259) single nucleotide polymorphisms (SNPs) to diabetic and non-diabetic retinopathy by using the non-parametric as well as the parametric linkage analysis. The strongest signal is present for the PSMD9 variants with the diabetic retinopathy, in particular under the additive model. The 1,000 simulations performed for each significant test confirmed that the results are not due to random chance.

CONCLUSIONS

In summary, the PSMD9 IVS3+nt460, IVS3+nt437, E197G SNPs are linked to diabetic retinopathy and non-diabetic retinopathy in Italians.

T2D-nephropathy linkage within 12q24 locus

The 12q24 locus is linked to microcirculation pathology and type 2 diabetes (T2D) with nephropathy and entails the PSMD9 gene linked to T2D. We tested the PSMD9 T2D risk SNPs IVS3+nt460A>G, IVS3+nt437T>C and E197G for linkage to T2D-diabetic nephropathy in 200 Italians T2D families and show linkage to diabetic nephropathy.

Hypercholesterolemia and a candidate gene within the 12q24 locus

Background

The 12q24 locus entails at least one gene responsible for hypercholesterolemia. Within the 12q24 locus lies the gene of proteasome modulator 9 (PSMD9). PSMD9 is in linkage with type 2 diabetes (T2D), T2D-nephropathy and macrovascular pathology in Italian families and PSMD9 rare mutations contribute to T2D.

Aims

In the present study, we aimed at determining whether the PSMD9 T2D risk single nucleotide polymorphisms (SNPs) IVS3 + nt460 A > G, IVS3 + nt437 T > C and E197G A > G are linked to hypercholesterolemia in 200 T2D Italian families.

Methods

We characterized 200 Italian families for presence and/or absence of hypercholesterolemia characterized by LDL levels ≥ 100 mg/dl in drug-naïve patients and/or presence of a diagnosis of hypercholesterolemia in a patient treated with statin medication. The phenotypes were described as unknown in all cases in which the diagnosis was either unclear or the data were missing. We tested in the 200 Italians families for evidence of linkage of the PSMD9 SNPs with hypercholesterolemia. The non-parametric linkage analysis was performed for the qualitative phenotype by using the Merlin software; the Lod score and correspondent P-value were calculated. For the significant linkage score, 1000 replicates were performed to calculate the empirical P-value.

Results

The PSMD9 gene SNPs studied show linkage to hypercholesterolemia. The results are not due to random chance.

Conclusions

PSMD9 should be tested in all populations reporting linkage to hypercholesterolemia within the chromosome 12q24 locus. The impact of this gene on hypercholesterolemia and contribution to cardio- and cerebrovascular events may be high.

Proteasome modulator 9 and macrovascular pathology of T2D

Aims

Coronary artery disease (CAD) and stroke share a major linkage at the chromosome 12q24 locus. The same chromosome region entails at least a major risk gene for type 2 diabetes (T2D) within NIDDM2, the non-insulin-dependent-diabetes 2 locus. The gene of Proteasome Modulator 9 (PSMD9) lies in the NIDDM2 region and is implicated in diabetes in mice. PSMD9 mutations rarely cause T2D and common variants are linked to both late-onset T2D and maturity-onset-diabetes of the young (MODY3). In this study, we aimed at determining whether PSMD9 is linked to macrovascular pathology of T2D.

Methods and Results

In our 200 T2D families from Italy, we characterized the clinical phenotype of macrovascular pathology by defining the subjects for presence or absence of CAD, stroke and/or transitory ischemic attacks (TIA), plaques of the large arterial vessels (macro-vasculopathy) and arterial angioplasty performance. We then screened 200 T2D siblings/families for PSMD9 +nt460A/G, +nt437C/T and exon E197G A/G single nucleotide polymorphisms (SNPs) and performed a non-parametric linkage study to test for linkage for coronary artery disease, stroke/TIA, macro-vasculopathy and macrovascular pathology of T2D. We performed 1,000 replicates to test the power of our significant results. Our results show a consistent significant LOD score in linkage with all the above-mentioned phenotypes. Our 1000 simulation analyses, performed for each single test, confirm that the results are not due to random chance.

Conclusions

In summary, the PSMD9 IVS3+nt460A/G, +nt437C/T and exon E197G A/G SNPs are linked to CAD, stroke/TIA and macrovascular pathology of T2D in Italians.

Epigenetics and biomarkers in the staging of neuropsychiatric disorders

Epigenetics, or alterations in the phenotype or gene expression due to mechanisms other than changes in the underlying DNA sequence, reflects the sensitivity and responsiveness of human and animal brains in constantly varying circumstances regulating gene expression profiles that define the biomarkers and present the ultimate phenotypical outcomes, such as cognition and emotion. Epigenetics is associated with functionally relevant alterations to the genome in such a fashion that under the particular conditions of early, adolescent, and adult life, environmental signals may activate intracellular pathways that remodel the "epigenome," triggering changes in gene expression and neural function. Thus, genetic influences in neuropsychiatric disorders that are subject to clinical staging, epigenetics in schizophrenia, epigenetic considerations in the expression of sensorimotor gating resulting from disease conditions, biomarkers of drug use and addiction, current notions on the role of dopamine in schizophrenia spectrum disorders, and the discrete interactions of biomarkers in persistent memory were to greater or lesser extents reflected upon. The relative contributions of endophenotypes and epistasis for mediating epigenetic phenomena and the outcomes as observed in the analysis of biomarkers appear to offer a multitude of interactive combinations to further complicate the labyrinthine machinations of diagnosis, intervention, and prognosis.

PSMD9 is linked to MODY3

Type 2 diabetes has a replicated linkage on chromosome12q24.2 (NIDDM2 locus/non-insulin-dependent diabetes mellitus 2 locus), near the HNF-1alpha/MODY3 gene. The MODY3 gene is not responsible for this linkage. PSMD9--contributing to T2D in Italians by rare unique mutations and by the common haplotype A/T/G--lies in the NIDDM2 region. By genotyping the two markers D12S1721/D12S2073 nearby the MODY3 gene in our unrelated T2D cases, we previously excluded that the PSMD9 SNPs are in linkage disequilibrium (LD) with the MODY3 gene. In the present study, we aimed at identifying whether the PSMD9 A/T/G haplotype is present in the Italy-1 and Italy-3 MODY3 families and whether it cosegregates with diabetes/MODY3. We raised the question whether there is a digenic additive model within the MODY3 families to which the PSMD9 A/T/G haplotype contributes. We demonstrated that the PSMD9 A/T/G haplotype is linked to the MODY3 established mutations in the Italy-1 and Italy-3 families. By non-parametric and parametric linkage analyses, and LD modeling, in the Italy-1 and Italy-3 families we hereby show that the MODY3 mutation and the PSMD9 IVS3 + nt460A/IVS3 + nt437T/G197 SNPs act in an additional model to cause diabetes. Since in the two MODY3 Italian families the PSMD9 A/T/G haplotype is linked to MODY3, it contributes to MODY3/diabetes via an additional model. All MODY3 families should be tested for the PSMD9 A/T/G haplotype. The potential clinical impact of our study is of relevance.