Metabotropic glutamate receptor genetic variants and peripheral receptor expression affects trait scores of autistic probands

Glutamate (Glu) is important for memory and learning. Hence, Glu imbalance is speculated to affect autism spectrum disorder (ASD) pathophysiology. The action of Glu is mediated through receptors and we analyzed four metabotropic Glu receptors (mGluR/GRM) in Indo-Caucasoid families with ASD probands and controls. The trait scores of the ASD probands were assessed using the Childhood Autism Rating Scale2-ST. Peripheral blood was collected, genomic DNA isolated, and GRM5 rs905646, GRM6 rs762724 & rs2067011, and GRM7 rs3792452 were analyzed by PCR/RFLP or Taqman assay. Expression of mGluRs was measured in the peripheral blood by qPCR. Significantly higher frequencies of rs2067011 'A' allele/ AA' genotype were detected in the probands. rs905646 'A 'exhibited significantly higher parental transmission. Genetic variants showed independent as well as interactive effects in the probands. Receptor expression was down-regulated in the probands, especially in the presence of rs905646 'AA', rs762724 'TT', rs2067011 'GG', and rs3792452 'CC'. Trait scores were higher in the presence of rs762724 'T' and rs2067011 'G'. Therefore, in the presence of risk genetic variants, down-regulated mGluR expression may increase autistic trait scores. Since our investigation was confined to the peripheral system, in-depth exploration involving peripheral as well as central nervous systems may validate our observation.

Glutamate receptor genetic variants affected peripheral glutamatergic transmission and treatment induced improvement of Indian ADHD probands

Attention deficit hyperactivity disorder (ADHD), a childhood-onset neurobehavioral disorder, often perturbs scholastic achievement and peer-relationship. The pivotal role of glutamate (Glu) in learning and memory indicated an influence of Glu in ADHD, leading to the exploration of Glu in different brain regions of ADHD subjects. We for the first time analyzed GluR genetic variations, Glu levels, as well as expression of Glu receptors (GluR) in the peripheral blood of eastern Indian ADHD probands to find out the relevance of Glu in ADHD prognosis. After obtaining informed written consent for participation, peripheral blood was collected for analyzing the genetic variants, Glu level, and expression of target genes. Since ADHD probands are often treated with methylphenidate or atomoxetine for providing symptomatic remediation, we have also tested post-therapeutic improvement in the ADHD trait scores in the presence of different GluR genotypes. Two variants, GRM7 rs3749380 "T" and GRIA1 rs2195450 "C", exhibited associations with ADHD (P ≤ 0.05). A few GluR genetic variants showed significant association with higher trait severity, low IQ, lower plasma Glu level, down-regulated GluR mRNA expression, and poor response to medications. This indicates that down-regulated glutamatergic system may have an effect on ADHD etiology and treatment efficacy warranting further in-depth investigation.

Post-treatment symptomatic improvement of the eastern Indian ADHD probands is influenced by CYP2D6 genetic variations

OBJECTIVES

Symptomatic remediation from attention deficit hyperactivity disorder (ADHD)-associated traits is achieved by treatment with methylphenidate (MPH)/atomoxetine (ATX). We have analyzed the association of functional CYP2D6 variations, rs1065852, rs3892097, rs1135840, and rs1058164, with ADHD in the Indian subjects.

METHODS

Subjects were recruited following the Diagnostic and Statistical Manual for Mental Disorders. Trait scores were obtained from the Conner's Parents Rating Scale-Revised. After obtaining informed consent, blood was collected for DNA isolation, and genotyping was performed by PCR or TaqMan-based methods. Probands were treated with MPH or ATX based on age, symptoms, and drug availability. Treatment outcome was assessed using a structured questionnaire. Data obtained was analyzed to identify the association of CYP2D6 variations and the SLC6A3 rs28363170 with the treatment outcome.

RESULTS

The frequency of rs1135840 "G" and rs1065852 "G" was higher in the male ADHD probands. Bias in parental transmission (p=0.007) and association with higher trait scores were observed for rs1065852 "A". Independent influence of rs1065852 on ADHD was also observed. Probands carrying rs1065852 'GG', rs1135840 'CG', and rs28363170 10R exhibited significant symptomatic improvement with MPH, while probands with rs1135840 'CC' and rs28363170 9R showed improvement after ATX treatment.

CONCLUSIONS

ADHD probands having specific CYP2D6 genetic variations respond differentially to pharmaceutical intervention.

A three-pronged analysis confirms the association of the serotoninergic system with attention deficit hyperactivity disorder

BACKGROUND

The serotonin transporter (SERT), encoded by the solute carrier family 6 number 4 (SLC6A4) gene, controls serotonin (5-HT) availability and is essential for the regulation of behavioral traits. Two SLC6A4 genetic variants, 5-HTTLPR and STin2, were widely investigated in patients with various neurobehavioral disorders, including attention deficit hyperactivity disorder (ADHD).

METHODS

We analyzed the association of the 5-HTTLPR (L/S) and STin2 (10/12) variants, plasma 5-HT, and 5-hydroxyindole acetic acid (5-HIAA), as well as SERT messenger RNA (mRNA) with ADHD in the eastern Indian subjects. Nuclear families with ADHD probands (n = 274) and ethnically matched controls (n = 367) were recruited following the Diagnostic and Statistical Manual of Mental Disorders. Behavioral traits, executive function, and intelligence quotient (IQ) of the probands were assessed using the Conner's Parent Rating Scale - Revised, Parental Account of Children's Symptoms (PACS), Barkley Deficit in Executive Functioning-Child and Adolescent Scale, and Wechsler Intelligence Scale for Children-III, respectively. After obtaining informed written consent, peripheral blood was collected to analyze genetic variants, plasma 5-HT, 5-HIAA, and SERT mRNA expression.

RESULTS

ADHD probands showed a higher frequency of the 5-HTTLPR "L" allele and "L/L" genotype (P < 0.05), lower 5-HIAA level, and higher SERT mRNA expression. Scores for behavioral problems and hyperactivity were higher in the presence of the "S" allele and "S/S" genotype, while executive deficit was higher in the presence of the "L" allele. IQ score was lower in the presence of the STin2 "12" allele and L-12 haplotype.

CONCLUSION

Data obtained indicate a significant association of the serotoninergic system with ADHD, warranting further in-depth investigation.

Specific dopaminergic genetic variants influence impulsivity, cognitive deficit, and disease severity of Indian ADHD probands

BACKGROUND

Impulsivity (Imp), being one of the cardinal symptoms of Attention Deficit Hyperactivity Disorder (ADHD), often leads to inappropriate responses to stimuli. Since the dopaminergic system is the primary target for pharmaceutical intervention in ADHD, we investigated the association between ADHD-related Imp and functional gene variants of the dopamine transporter (SLC6A3) and catechol-O-methyltransferase involved in dopamine clearance.

METHODS AND RESULTS

Indo-Caucasoid families with ADHD probands (N = 217) were recruited based on the Diagnostic and Statistical Manual of Mental Disorders (DSM). Imp of the probands was assessed using the Domain Specific Imp Scale for Children and DSM. Peripheral blood was collected after obtaining informed written consent for participation, genomic DNA was isolated, and target sites were genotyped by DNA sequencing. The association of genetic variants with Imp was examined by the Quantitative trait analysis (QTA) and Analysis of variance (ANOVA). Post-Hoc analysis following QTA and ANOVA showed significant associations of rs2254408, rs2981359, and rs2239393 with different domains of Imp (P < 0.05). Various haplotypic combinations also showed statistically significant associations with Imp (P < 0.05). Multifactor dimensionality reduction models revealed strong effects of the variants on Imp. ADHD probands harboring the risk alleles exhibited a deficit in performance during cognitive assessment. Longitudinal follow-up revealed a significant association of rs2254408 with trait persistence.

CONCLUSION

The present study indicates the influence of the studied genetic variants on ADHD-associated imp, executive deficit, and disease persistence. Thus, these variants may be helpful as predictors for the success of individual therapeutic sessions during cognitive training.

Functional SLC6A3 polymorphisms differentially affect autism spectrum disorder severity: a study on Indian subjects

Imbalance in dopamine (DA) signaling is proposed to play a potential role in the etiology of Autism spectrum disorder (ASD) since, as a neuromodulator, DA regulates executive function, motor activity, social peering, attention as well as perception and subjects with ASD often exhibit deficit in these traits. Level of DA in the synaptic cleft is maintained by dopamine transporter (DAT) and hence, to identify the role of DAT in ASD, we have analyzed four functional genetic variants, rs28363170, rs3836790, rs2652511, rs27072, in nuclear families with ASD probands. Subjects were diagnosed based on Diagnostic and Statistical Manual for Mental Disorders and trait severity was assessed by Childhood Autism Rating Scale 2-Standard test. Informed written consent was obtained from the parents/care givers before recruitment followed by collection of peripheral blood for genomic DNA isolation. Target sites were investigated by PCR-based methods and data obtained was analyzed by population- as well as family-based statistical methods. Case-control analysis revealed significant higher frequencies of 9 repeat (9R) and 5 repeat (5R) alleles of rs28363170 and rs3836790 respectively in the ASD probands. Family-based analysis showed statistically significant higher paternal transmission of rs28363170 9R and rs2652511 T alleles. In the presence of rs28363170 9R, rs27072 C, rs3836790 6R6R, and rs2652511 CC variants, trait scores were higher. Studied variants showed independent as well as interactive effects, which varied based on gender of the probands. We infer that altered DA availability mediated through DAT may affect autistic traits warranting further in depth investigation in the field.

Analysis of association between components of the folate metabolic pathway and autism spectrum disorder in eastern Indian subjects

BACKGROUND

Folate has a pivotal role in maintaining different cellular processes including DNA integrity and neurotransmitter levels. Further, folate deficiency was reported in subjects with neuropsychiatric disorders including autism spectrum disorder (ASD).

METHODS AND RESULTS

We recruited ASD probands following the Diagnostic and Statistical Manual of Mental Disorder-IV/-5. Severity was assessed by the Childhood Autism Rating Scale2-Standard Test (CARS2-ST). Functional SNPs in reduced folate carrier1 (rs1051266), methylenetetrahydrofolate dehydrogenase (rs2236225), methylenetetrahydrofolate methyltransferase (rs1805087), methylenetetrahydrofolate reductase (rs1801133 and rs1801131), cystathionine-beta- synthase (rs5742905), and serine hydroxymethyltransferase (rs1979277) genes were analyzed in the ASD probands (N = 203), their parents and controls (N = 250) by PCR/TaqMan based methods. Plasma homocysteine and vitamin B12 levels were examined by Enzyme-Linked ImmunoSorbent Assay. Statistical analysis revealed higher frequencies of rs1051266 and rs1805087 "A" alleles (P = 8.233e-005 and P = 0.010 respectively) and rs1051266 "AA" genotype (P = 0.02) in the ASD probands. Gender based stratified analysis revealed higher frequency of rs1051266 "AA" in the male probands (P = 0.001) while frequencies of rs1805087 "A" (P = 0.001) and "AA" (P < 0.05), and rs2236225 "CC" (P = 0.03) were higher in the females. The case-control analysis also exhibited a significant difference in the occurrence of biallelic and triallelic haplotypes. rs1051266 "A", rs1979277 "T" and rs5742905 "C" alleles showed biased parental transmission (P = 0.02). CARS2-ST scores were higher in the presence of rs5742905 "T" while scores were lower in the presence of rs1979277 "T" and rs1051266 "A". ASD probands showed vitamin B12 deficiency.

CONCLUSION

Based on these observations, we infer that components needed for proper folate metabolism may influence ASD severity in this population.

Folate System Gene Variant rs1801394 66A>G may have a Causal Role in Down Syndrome in the Eastern Indian Population

Down syndrome (DS) is associated with trisomy of the 21^st chromosome in more than 95% cases. The extra chromosome mostly derives due to abnormal chromosomal segregation, i.e. non-disjunction, during meiosis. Earlier reports showed that abnormal folate metabolism can lead to DNA hypomethylation and abnormal chromosomal segregation. We analyzed three functional folate gene variants, namely 5-methyltetrahydrofolate-homocysteine methyltransferase rs1805087, 5-methyltetrahydrofolate-homocysteine methyltransferase reductase rs1801394, and reduced folate carrier 1 rs1051266, for contribution in the etiology of DS. Ethnically matched subjects including DS probands (N=183), their parents (N=273), and controls (N=286) were recruited after obtaining informed written consent for participation. Karyotype analysis confirmed trisomy 21 in DS patients recruited. Genomic DNA, purified from peripheral blood leukocytes was used for genotyping of the target sites by PCR based methods, and data obtained was subjected to population- as well as family-based association analysis. Frequency of rs1801394 ‘G’ allele and ‘GG’ genotype was higher in DS probands (P < 0.0001). Statistically significant higher occurrence of the ‘G’ allele in parents of DS probands (P < 0.0001) and maternal bias in transmission of the “G” allele was also noticed (P < 0.0001). Genetic model analysis demonstrated rs1801394 “G” as a risk allele under both dominant and recessive models. DS probands also showed higher occurrence of rs1051266 “G” (P = 0.05). Quantitative trait analysis revealed significant negative influence of rs1805087 “A” on birth weight. Screening for rs1801394 “G” could be useful in monitoring the risk of DS, at least in the studied population.

Association of Dopamine Transporter Gene with Heroin Dependence in an Indian Subpopulation from Manipur

Dopamine transporter (DAT) or solute carrier family 6 member 3 (SLC6A3) is a transmembrane protein regulating dopaminergic neurotransmission. It has been implicated in playing important roles in the dopaminergic reward pathways, and thus, DAT1 is a strong candidate gene for association studies with heroin dependence. A case-control study involving 279 individuals (147 controls and 132 heroin-dependent cases) was conducted. Ten polymorphisms of the DAT1 (SLC6A3) gene were analysed for its association with heroin dependence. Following the Hardy-Weinberg equilibrium (HWE) test, genetic association analyses were performed for the study groups. The post hoc statistical power of the study was 0.655 (65.5%). Single-nucleotide polymorphism (SNP) rs246997 was found to be significantly associated with heroin dependence at allelic, genotypic, and haplotypic levels. A significant difference in the distribution of 11R allele and 10R/11R genotype of rs28363170 between heroin-dependent cases and controls was also observed. Nominal significance at degrees of freedom (df) = 5 was also observed for rs28363170. Five bimarker-based haplotype combinations were also found to be associated with heroin dependence. For the first time, 13R allele (7R/13R genotype) and 14R allele (7R/14R genotype) were identified for rs3836790 in the population. The study also reports that the 11R allele and 10R/11R genotype of rs28363170 is associated with protection against heroin dependence. 7R and 6R alleles were also found to be the common alleles of rs3836790 in the study population. The study provides evidence for the association of polymorphisms of DAT1 (SLC6A3) with heroin dependence.

A single nucleotide polymorphism in OPRM1(rs483481) and risk for heroin use disorder

Opioid receptor mu1 (OPRM1) is the target of many opioid drugs, and it is known to have affinity toward both endogenous and exogenous opioids, opiate and opioid analgesic drugs. The present study was undertaken to explore association of single nucleotide polymorphisms (SNPs) in the OPRM1 gene with heroin use disorder. Ten OPRM1 polymorphisms were analyzed in 132 cases and 147 healthy controls. The SNP rs483481 showed significant allelic, genotypic and haplotypic association (Allelic: p-value = 0.003, OR = 1.75, CI = 1.21-2.55) (Genotypic: p-value = 0.003, OR = 1.72, CI = 1.08-2.75) with heroin use disorder. Allelic and genotypic association remained significant even after multiple testing corrections with 1000 permutations. A significant positive correlation between 'Number of times drug abstained' and 'rs483481-AA genotype' (p-value = 0.002; Pearson correlation = 0.265) was also observed. One-way ANOVA analysis demonstrated significant association of rs483481 with 'number of times drug abstained' (F = 4.86, p-value =0.009). 'A' allele and 'AA' genotype of marker rs483481 seem to confer protective effect while 'G' allele and 'GG' genotype potentiates risk for heroin use disorder. OPRM1 is found to be associated with heroin use disorder in the studied Manipuri cohort. The study suggests that individuals with G allele and GG genotypes at rs483481 could be more vulnerable to heroin dependence, and it could be taken into consideration in prevention and intervention programs.

Gender-Specific Effect of 5-HT and 5-HIAA on Threshold Level of Behavioral Symptoms and Sex-Bias in Prevalence of Autism Spectrum Disorder

Platelet hyperserotonemia in a subset of Autism Spectrum Disorder (ASD) probands, efficacy of selective serotonin reuptake inhibitors (SSRIs) in reducing behavioral deficits and gender-bias in normal serotonin (5-hydroxy tryptamine or 5-HT) synthesis suggest disruption in stringent regulation of serotonin metabolism in ASD. Therefore, we investigated the changes in 5-HT and 5-hydroxy indole acetic acid (5-HIAA) in ASD probands to assess its effect on the behavior of male and female probands. ASD cases (n = 215) were examined using childhood autism rating scale (CARS). Platelet 5-HT (104 cases and 26 controls) and platelet/plasma 5-HIAA (73 cases and 17 controls) were estimated using high performance liquid chromatography coupled with electrochemical detector (HPLC-ECD). In male probands, we observed increase in platelet 5-HT content in association with increase in the score for adaptive responses and increase in platelet 5-HIAA levels with concomitant decline in the score for intellectual response. Age did not influence the neurochemical parameters, but imitation, listening responses and nonverbal communication scores decreased with age. Conversely in female probands, plasma 5-HIAA level significantly attenuated with age, when platelet 5-HT content remained unchanged. Interestingly, platelet/plasma 5-HT and plasma 5-HIAA were higher in female controls. Female probands displayed severe autism-associated behaviors. Overall results indicate gender-bias in 5-HT and 5-HIAA regulation, which probably increases the threshold level of ASD phenotypes in the females, thereby affecting ASD prevalence in a sex-specific manner.

Dopaminergic gene analysis indicates influence of inattention but not IQ in executive dysfunction of Indian ADHD probands

Organizational inefficiency and inattention are speculated to be the reason for executive deficit (ED) of ADHD probands. Even with average IQ, probands often perform poorly due to higher inattention. Pharmacotherapy, cognitive behavioural therapy, and counselling provide only symptomatic relief. Several candidate genes showed involvement with ADHD; the most consistent are dopamine receptor 4 (DRD4) and solute carrier family 6 member 3 (SLC6A3). We analyzed association of rarely investigated DRD4 and SLC6A3 variants with ADHD core traits in Indo-Caucasoid probands. ED, inattention, organizational efficiency, and IQ were measured by Barkley Deficit in Executive Functioning-Child & Adolescent scale, DSM-IV-TR, Conners' Parent Rating Scale-revised, and WISC respectively. Target sites were analyzed by PCR, RFLP, and/or Sanger sequencing of genomic DNA. DRD4 variants mostly affected inattention while SLC6A3 variants showed association with IQ. Few DRD4 and SLC6A3 variants showed dichotomous association with IQ and inattention. DRD4 Exon3 VNTR >4R showed negative impact on all traits excepting IQ. Inattention showed correlation with attention span, organizational efficiency, and ED, while IQ failed to do so. We infer that IQ and attention could be differentially regulated by dopaminergic gene variants affecting functional efficiency in ADHD and the two traits should be considered together for providing better rehabilitation.

Parental age and developmental milestones: pilot study indicated a role in understanding ADHD severity in Indian probands

Background

In different ethnic groups, birth related factors have shown significant influence in the etiology of Attention deficit hyperactivity disorder (ADHD). Based on these interesting findings, we aimed to investigate association between different pre- and post natal variables and ADHD associated traits in Indian subjects.

Methods

ADHD Probands recruited based on the DSM-IV, were assessed by the Conner’s Parent Rating Scale for behavioral problem (BPr), inattention (IA), hyperactivity (HA) and ADHD index (AI). Impulsivity (Imp) was assessed by the Tsukuyama scale.

Results

Higher paternal (Std β = 0.23) and lower maternal (Std β = 0.21) age showed significant association with Imp of the probands. Higher paternal age also revealed association with BPr (Std β = 0.18). Age of onset was distinctly associated with AI (Std β < 0.16) while developmental delay was negatively correlated with BPr, Imp, IA and birth weight (r < − 0.13); also confirmed by Posthoc-ANOVA (P < 0.05).

Conclusion

We infer that parental age, developmental delay and birth related variables may have a cumulative effect on ADHD symptom severity.

Electronic supplementary material

The online version of this article (10.1186/s12887-019-1483-x) contains supplementary material, which is available to authorized users.

Autistic traits and components of the folate metabolic system: an explorative analysis in the eastern Indian ASD subjects

Objectives: Proper metabolism of the folate is crucial for maintaining DNA integrity, chromosome structure, methylation, as well as gene expression, and thus, folate is speculated to contribute to the etiology of different disorders. Since the etiology of autism spectrum disorder (ASD) is believed to be influenced by both genetic and environmental factors, we hypothesized that functional single nucleotide polymorphisms (SNPs) affecting folate metabolic pathway may have a causal role in the etiology of ASD. Methods: We analyzed three SNPs, rs2071010, rs2298444 and rs1801198 (in the folate receptor 1, folate receptor 2 and transcobalamin 2, respectively), in 867 ethnically matched subjects including 206 ASD probands and 286 controls. Plasma vitamin B₆ and folate were measured in age-matched probands and controls. Results: ASD probands showed a higher frequency of rs2298444 'A' allele (P = 0.01) and genotypes with 'A' allele (P = 0.03) when compared with the controls. rs1801198 'C' allele and 'CG' genotype also showed higher occurrence in the probands (P = 0.009 and 0.005, respectively). Gender-based stratified analysis revealed a significant higher frequency of rs2298444 'A' allele (P = 0.003), genotypes with rs2298444 'A' allele (P = 0.003) and rs1801198 CG (P = 0.001) in the male probands. Studied variants also showed statistically significant associations with ASD-associated traits measured by the Childhood Autism Rating Scale. ASD subjects exhibited gross deficiency in vitamin B₆ level when compared with age-matched controls (P < 0.001), which correlated with risk genetic variants. Discussion: We infer from this pioneering study on eastern Indian subjects that vitamin B₆ deficiency, along with risk gene variants, may affect ASD-associated symptoms, warranting further investigation in large cohorts.

Preparation and properties of AlN (aluminum nitride) powder/thin films by single source precursor

The precursor hexa urea aluminate(iii) was pyrolysed at various temperature (800 °C to 1000 °C) and pressure (100 Torr to 1 Torr) under inert atmosphere to study the effect of temperature, pressure and inert gases for the conversion of precursor to AlN material/thin films.

Genetic variants of the folate metabolic system and mild hyperhomocysteinemia may affect ADHD associated behavioral problems

An etiologically complex disorder, Attention Deficit Hyperactivity Disorder (ADHD), is often associated with various levels of cognitive deficit. Folate/vitamin B₉ is crucial for numerous biochemical pathways including neural stem cell proliferation and differentiation, regulation of gene expression, neurotransmitter synthesis, myelin synthesis and repair, etc. and a scarcity has often been linked to cognitive deficit. Our pilot study in the field revealed significant association of few genetic variants with ADHD. Mild hyperhomocysteinemia and vitamin B₁₂ deficiency was also noticed in the probands. In the present study additional genetic variants, folate and vitamin B₆, which may affect folate-homocysteine metabolic pathway, were investigated in 866 individuals including nuclear families with ADHD probands (N=221) and ethnically matched controls (N=286) to find out whether ADHD associated traits are affected by these factors. Population based analysis revealed significant over representation of MTRR rs1801394 "G" allele and "GG" genotype in all as well as male probands. Stratified analysis showed significantly higher frequency of RFC1 rs1051266 and BHMT rs3733890 "AG" genotypes in full term and prematurely delivered ADHD probands respectively. Probands with rs1801394 "GG" genotype and BHMT rs3733890 "G" allele showed association with hyperhomocysteinemia. MTHFR rs1801131, MTR rs1805087 and BHMT rs3733890 also showed association with ADHD index. While rs1051266, rs1801131, and rs1805087 showed association with behavioral problems, rs3733890 was associated with ODD score. Conduct problem exhibited association with RFC1 rs1051266, MTHFR rs1801133 and MTRR rs1801394. Gene-gene interaction analysis revealed positive synergistic interactions between rs1051266, rs1801131 and rs1801394 in the probands as compared to the controls. It can be inferred from the data obtained that folate system genetic variants and mild hyperhomocysteimenia may affect ADHD associated traits by attenuating folate metabolism.

Pilot study indicate role of preferentially transmitted monoamine oxidase gene variants in behavioral problems of male ADHD probands

Background

Attention deficit hyperactivity disorder (ADHD) is an etiologically complex childhood onset neurobehavioral disorder characterized by age-inappropriate inattention, hyperactivity, and impulsivity. Symptom severity varies widely and boys are diagnosed more frequently than girls. ADHD probands were reported to have abnormal transmissions of dopamine, serotonin, and/or noradrenaline. Monoamine oxidase A (MAOA) and B (MAOB), mitochondrial outer membrane bound two isoenzymes, mediate degradation of these neurotransmitters and thus regulating their circulating levels. Case-control analyses in different populations, including Indians, suggested involvement of MAOA and MAOB genes in the etiology of ADHD. Due to high heritability rate of ADHD, we tested familial transmission of MAOA and MAOB variants to ADHD probands in 190 nuclear families having ADHD probands from Indo-Caucasoid ethnicity.

Methods

Subjects were recruited following the Diagnostic and Statistical Manual of Mental Disorders-4th edition (DSM-IV). Appropriate scales were used for measuring the behavioral traits in probands. Genotyping was performed through PCR-based amplification of target sites followed by DNA-sequencing and/or gel-electrophoresis. Data obtained were analyzed by family based statistical methods.

Results

Out of 58 variants present in the analyzed sites only 15 were found to be polymorphic (30 bp-uVNTR, rs5906883, rs1465107, rs1465108, rs5905809, rs5906957, rs6323, rs1137070 from MAOA and rs4824562, rs56220155, rs2283728, rs2283727, rs3027441, rs6324, rs3027440 from MAOB). Statistically significant maternal transmission of alleles to male probands was observed for MAOA rs5905809 ‘G’ (p = 0.04), rs5906957 ‘A’ (p = 0.04), rs6323 ‘G’ (p = 0.0001) and MAOB rs56220155 ‘A’ (p = 0.002), rs2283728 ‘C’ (p = 0.0008), rs2283727 ‘C’ (p = 0.0008), rs3027441 ‘T’ (p = 0.003), rs6324 ‘C’ (p = 0.003), rs3027440 ‘T’ (p = 0.0002). Significantly preferential maternal transmissions of different haplotype combinations to male probands were also noticed (p < 0.05), while female probands did not reveal such transmission bias. Behavioral traits of male probands exhibited significant association with gene variants. Age of the mother at pregnancy also revealed association with risk variants of male probands.

Conclusions

It may be inferred that the MAOA and MAOB variants may contribute to the etiology of ADHD in the Indo-Caucasoid population and could be responsible for higher occurrence of ADHD in the boys.

Electronic supplementary material

The online version of this article (10.1186/s12881-017-0469-5) contains supplementary material, which is available to authorized users.

Significance of Dopaminergic Gene Variants in the Male Biasness of ADHD

OBJECTIVE

ADHD is frequently detected in boys though there is no established cause. One possibility is that genes predisposing to ADHD have sexually dimorphic effects. With an aim to find out the reason for this male biasness, contribution of 14 functional polymorphisms was investigated in ADHD subjects.

METHOD

Genomic DNA of probands, their parents, and ethnically matched controls was subjected to analysis of single-nucleotide polymorphisms and variable number of tandem repeats (VNTRs).

RESULTS

Case-control analysis revealed significant higher occurrence of DAT1 intron 8 VNTR "5R" allele ( p = .028), DBH rs1108580 "A" allele ( p = .027), and MAOA-u VNTR-rs6323 3R-T haplotype ( p = .007) in male probands. Family-based analysis showed significant preferential transmission of Dopamine receptor D4 exon 3 VNTR-rs1800955 7R-T haplotype from parents to male probands ( p = .008). Interaction between DBH gene variants and low enzymatic activity was also noticed, especially in male probands.

CONCLUSION

Data obtained may partly answer the male biasness of ADHD.

The Dopamine Receptor D5 May Influence Age of Onset: An Exploratory Study on Indo-Caucasoid ADHD Subjects

The objective was to investigate contribution of the dopamine receptor 5 (DRD5) gene variants in the symptoms of attention-deficit/hyperactivity disorder (ADHD) probands since brain regions identified to be affected in these group of patients have higher expression of the DRD5 receptor. Out of 22 exonic variants, 19 were monomorphic in the Indo-Caucasoid individuals. rs6283 "C" and rs113828117 "A" exhibited significant higher occurrence in families with ADHD probands. Several haplotypes showed biased occurrence in the probands. Early and late onset groups exhibited significantly different genotypic frequencies. A new G>A substitution was observed in the control samples only. The late onset group exhibited higher scores for hyperactivity as compared to the early onset group. The authors infer that the age of onset of ADHD may at least partially be affected by DRD5 variants warranting further investigation on the role of DRD5 in the disease etiology.

Monoamine oxidase B gene variants associated with attention deficit hyperactivity disorder in the Indo-Caucasoid population from West Bengal

Background

Attention deficit hyperactivity disorder (ADHD) is characterized by symptoms of inattention, excessive motor activity and impulsivity detected mostly during childhood. These traits are known to be controlled by monoamine neurotransmitters, chiefly dopamine, serotonin and norepinephrine. Monoamine oxidase A (MAOA) and B (MAOB), two isoenzymes bound to the outer membrane of mitochondria, are involved in the degradation of monoamines and were explored for association with ADHD in different ethnic groups. In the present study, few exonic as well as intronic MAOB variants were analyzed in ADHD probands (N = 150) and ethnically matched controls (N = 150) recruited following the Diagnostic and Statistical Manual for Mental Disorders-4^th edition (DSM-IV). Appropriate scales were used for measuring the behavioural attributes. Gene variants were analyzed by amplification of target sites followed by DNA sequencing and data obtained were analyzed by population based statistical methods.

Results

Out of 34 variants present in the analyzed sites, only seven functional variants, rs4824562, rs56220155, rs2283728, rs2283727, rs3027441, rs6324 and rs3027440, were found to be polymorphic. rs2283728 ‘C’ (P = 3.45e-006) and rs3027440 ‘T’ (P = 0.02) alleles showed higher frequencies in ADHD probands as compared to controls. rs56220155 ‘A’ (P = 0.04) allele and ‘GA’ (P = 0.04) genotype showed higher frequencies in the male and female ADHD probands respectively as compared to sex-matched controls. Analysis of pairwise linkage disequilibrium revealed striking differences between probands and controls. Haplotype analysis revealed significantly higher occurrence of different haplotypes in the ADHD probands while some haplotypes were detected in the controls only. Higher scores for conduct problems were found to be associated with rs56220155 ‘A’ (P = 0.05) allele in the male ADHD probands. Multifactor dimensionality reduction analysis showed independent as well as interactive effects of polymorphic variants which were more robust in the male probands.

Conclusions

Since all the polymorphic variants analyzed were functional, it may be inferred that MAOB gene variants are contributing to the etiology of ADHD in the Indo-Caucasoid population from eastern India which merits further in depth analysis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12863-016-0401-6) contains supplementary material, which is available to authorized users.

Engineering the physical parameters for continuous synthesis of fullerene peapods

Previous efforts to insert fullerenes into a carbon nanotube (CNT) involved the isolated synthesis of CNTs and fullerenes and then annealing CNTs and fullerenes together for encapsulation. We demonstrated the process for the continuous production of fullerene peapods inside the arc instrument by modifying the conventional arc ablation system, which can be repeated to obtain the desired mass scale product. Inside the arc discharge unit, by using the tunable external magnetic field, the double-walled CNTs (DWCNTs) were first synthesized and then directed to deposit onto the water cooled aluminium (Al) plate. The openings were created on DWCNTs by controlled heating of the Al plate and then fullerenes were synthesized and deposited on DWCNTs. In the arc instrument, fullerenes were finally directed to enter into DWCNTs from the defect sites by heating the Al plate in a vacuum. The formation of the peapod was established by the structure-property studies despite the huge deposition of metal catalyst nanoparticles and fullerenes on the surface of the nanotube which were a serious challenge for molecular level characterization of the grown peapod structures.

A pilot study on the contribution of folate gene variants in the cognitive function of ADHD probands

Genetic abnormalities in components important for the folate cycle confer risk for various disorders since adequate folate turnover is necessary for normal methylation, gene expression and chromosome structure. However, the system has rarely been studied in children diagnosed with attention deficit hyperactivity disorder (ADHD). We hypothesized that ADHD related cognitive deficit could be attributed to abnormalities in the folate cycle and explored functional single nucleotide polymorphisms in methylenetetrahydrofolate dehydrogenase (rs2236225), reduced folate carrier (rs1051266), and methylenetetrahydrofolate reductase (rs1801131 and rs1801133) in families with ADHD probands (N = 185) and ethnically matched controls (N = 216) recruited following the DSM-IV. After obtaining informed written consent for participation, peripheral blood was collected for genomic DNA isolation and PCR-based analysis of target sites. Data obtained was analyzed by UNPHASED. Interaction between sites was analyzed by the multi dimensionality reduction (MDR) program. Genotypic frequencies of the Indian population were strikingly different from other ethnic groups. rs1801133 "T" allele showed biased transmission in female probands (p < 0.05). Significant difference in genotypic frequencies for female probands was also noticed. rs1801131 and rs1801133 showed an association with low intelligence quotient (IQ). MDR analysis exhibited independent effects and contribution of these sites to IQ, thus indicating a role of these genes in ADHD related cognitive deficit.

Sexual dimorphic effect in the genetic association of monoamine oxidase A (MAOA) markers with autism spectrum disorder

Autism spectrum disorders are heritable and behaviorally-defined neurodevelopmental disorders having skewed sex ratio. Serotonin as modulator of behavior and implication of serotonergic dysfunction in ASD etiology corroborates that serotonergic system genes are potential candidates for autism susceptibility. In the current study X-chromosomal gene, MAOA responsible for degradation of serotonin is investigated for possible association with ASD using population-based approach. Study covers analysis of 8 markers in 421 subjects including cases and ethnically-matched controls from West Bengal. MAOA marker, rs6323 and various haplotypes formed between the markers show significant association with the disorder. Stratification on the basis of sex reveals significant genetic effect of rs6323 with low activity T allele posing higher risk in males, but not in females. Haplotypic association results also show differential effect both in males and females. Contrasting linkage disequilibrium pattern between pair of markers involving rs6323 in male cases and controls further supports the sex-bias in genetic association. Bioinformatic analysis shows presence of Y-encoded SRY transcription factor binding sites in the neighborhood of rs1137070. C allele of rs1137070 causes deletion of GATA-2 binding site and GATA-2 is known to interact with SRY. This is the first study highlighting male-specific effect of rs6323 marker and its haplotypes in ASD etiology and it suggests sexual dimorphic effect of MAOA in this disorder. Overall results of this study identify MAOA as a possible ASD susceptibility locus and the differential genetic effect in males and females might contribute to the sex ratio differences and molecular pathology of the disorder.

Potential contribution of monoamine oxidase a gene variants in ADHD and behavioral co-morbidities: scenario in eastern Indian probands

Attention deficit hyperactivity disorder (ADHD) is the most frequently diagnosed behavioral disorder in children with a high frequency of co-morbid conditions like conduct disorder (CD) and oppositional defiant disorder (ODD). These traits are controlled by neurotransmitters like dopamine, serotonin and norepinephrine. Monoamine oxidase A (MAOA), a mitochondrial enzyme involved in the degradation of amines, has been reported to be associated with aggression, impulsivity, depression, and mood changes. We hypothesized that MAOA can have a potential role in ADHD associated CD/ODD and analyzed 24 markers in a group of Indo-Caucasoid subjects. ADHD probands and controls (N = 150 each) matched for ethnicity and gender were recruited following the Diagnostic and Statistical Manual for Mental Disorders-IV. Appropriate scales were used for measuring CD and ODD traits. Markers were genotyped by PCR-based methods and data obtained analyzed using the Cocaphase program under UNPHASED. Only eight markers were found to be polymorphic. rs6323 "G" allele showed higher frequencies in ADHD (P = 0.0023), ADHD + CD (P = 0.03) and ADHD + ODD (P = 0.01) as compared to controls. Haplotype analysis revealed statistically significant difference for three haplotypes in ADHD cases (P < 0.02). Statistically significant differences were also noticed for haplotypes in ADHD + CD and ADHD + ODD cases (P < 0.01). LD analysis showed significant variation in different groups. Multidimensionality reduction analysis showed independent as well as interactive effects of markers. Genotypes showed correlation with behavioral problems in ADHD and ADHD + CD. We interpret that MAOA gene variants may contribute to the etiology of ADHD as well as associated co-morbid CD and ODD in this ethnic group.

Immobilization of individual nanotubes in graphitic layers for electrical characterization

A simple route is followed to produce an abundance of individual carbon nanotubes (CNTs) immobilized in graphitic layers to counter the challenge of locating individual CNTs and restrict the lateral displacement of CNTs due to the high electrostatic force exerted by a scanning tunnelling microscope tip for electrical characterization. Graphitic layers are selected for the embedding matrix as graphite and the nanotubes have a similar work function and hence would not perturb the electrical configuration of the nanotube. Solvent mediated exfoliation of graphite layers to insert the nanotubes was preferred over oxidative expansion, as oxidation could perturb the electrical configuration of graphite. During the exfoliation of graphite the optimized amount of nanotubes was introduced into the medium such that an individual nanotube could be immobilized in few-layer graphene followed by precipitation and centrifugation. The dose and the time of sonication were optimized to ensure that damage to the walls of the nanotubes is minimized, although the ultrasonication causes scissoring of the nanotube length. This procedure for immobilizing nanotubes in graphitic layers would be equally applicable for functionalized CNTs as well. The capability of embedding individual nanotubes into a similar work function material in an organic solvent, which could then be transferred onto a substrate by simple drop casting or spin coating methods, has an added advantage in sample preparation for the STM characterization of CNTs.

Down Syndrome Related Muscle Hypotonia: Association with COL6A3 Functional SNP rs2270669

Down syndrome (DS), the principal cause for intellectual disability, is also associated with hormonal, immunological, and gastrointestinal abnormalities. Muscle hypotonia (MH) and congenital heart diseases (CHD) are also frequently observed. Collagen molecules are essential components for maintaining muscle integrity and are formed by the assembly of three chains, alpha 1–3. The type VI collagen is crucial for cardiac as well as skeletal muscles. The COL α1 (VI) and α2 (VI) chains are encoded by genes located at the 21st chromosome and are expected to have higher dosage in individuals with DS. The α 3 (VI) chain is encoded by the COL6A3 located at the chromosome 2. We hypothesized that apart from COL6A1 and COL6A2, COL6A3 may also have some role in the MH of subjects with DS. To find out the relevance of COL6A3 in DS associated MH and CHD, we genotyped two SNPs in COL6A3, rs2270669 and rs2270668, in individuals with DS. Subjects with DS were recruited based on the Diagnostic and Statistical Manual for Mental Disorders-IV and having trisomy of the 21st chromosome. Parents of individuals with DS and ethnically matched controls were enrolled for comparison. Informed written consent was obtained for participation. Peripheral blood was used for isolation of genomic DNA. Target genetic loci were studied by DNA sequence analysis. Data obtained was subjected to population – as well as family-based statistical analysis. rs2270668 was found to be non-polymorphic in the studied population. rs2270669 showed significant association of the “C” allele and “CC” genotype with DS probands having MH (P = 0.02). Computational analysis showed that rs2270669 may induce structural and functional alterations in the COL α3 (VI). Interaction of COLα3 (VI) with different proteins, crucial for muscle integrity, was also noticed by computational methods. This pioneering study on COL6A3 with DS related MH thus indicates that rs2270669 “C” could be considered as a risk factor for DS related MH.

Potential contribution of SIM2 and ETS2 functional polymorphisms in Down syndrome associated malignancies

Background

Proper expression and functioning of transcription factors (TFs) are essential for regulation of different traits and thus could be crucial for the development of complex diseases. Subjects with Down syndrome (DS) have a higher incidence of acute lymphoblastic leukemia (ALL) while solid tumors, like breast cancer (BC) and oral cancer (OC), show rare incidences. Triplication of the human chromosome 21 in DS is associated with altered genetic dosage of different TFs. V-ets erythroblastosis virus E26 oncogene homolog 2 (ETS2) and Single Minded 2 (SIM2) are two such TFs that regulate several downstream genes involved in developmental and neurological pathways. Here we studied functional genetic polymorphisms (fSNP) in ETS2 and SIM2 encoding genes in a group of patients and control subjects to better understand association of these variants with DS phenotypes.

Methods

We employed an in silico approach to identify potential target pathways of ETS2 and SIM2. fSNPs in genes encoding for these two TFs were identified using available databases. Selected sites were genotyped in individuals with DS, their parents, ALL, BC, OC as well as ethnically matched control individuals. We further analyzed these data by population-based statistical methods.

Results

Allelic/genotypic association analysis showed significant (P < 0.03) differences of rs2070530, rs1051476, rs11254, rs711 for DS subjects compared to control. rs711 also exhibited significantly different genotypic distribution pattern in parents of DS probands (P < 0.02) and BC patients (P < 0.02). Interaction analysis revealed independent main effect of rs711 in all the groups, while rs11254 exhibited independent main effect in DS subjects only. High entropy values were noticed for rs461155 in the solid tumor groups. Significant interactive effects of rs2070531 with rs1051475, rs1051476, rs11254 were observed in all the groups except DS.

Conclusions

We infer from the present investigation that the difference in frequencies of fSNPs and their independent as well as interactive effects may be the cause for altered expression of SIM2 and ETS2 in DS and malignant groups, which affects different downstream biological pathways. Thus, altered expression of SIM2 and ETS2 could be one of the reasons for variable occurrence of different malignant conditions in DS.

Exploratory investigation on functional significance of ETS2 and SIM2 genes in Down syndrome

Trisomy of the 21st chromosome leads to an over dosage of several regulatory genes in Down syndrome (DS). Though allelic and genotypic combinations formed between genes are interesting, till date, this particular area has never been explored in DS. In the present investigation four SNPs in two transcription factors, Single minded 2 (SIM2) and V-ets erythroblastosis virus E26 oncogene homolog2 (ETS2), located in the 21st chromosome were genotyped to understand their role in DS. Genomic DNA of eastern Indian probands with DS (N = 132), their parents (N = 209) and ethnically matched controls (N = 149) was subjected to PCR-based analyses of functionally important SNPs followed by statistical analyses. ETS2 rs461155 showed high heterozygosity in DS. Significantly lower frequency of SIM2 C-G haplotype (rs2073601-rs2073416) was noticed in individuals with DS (P value = 0.01669) and their fathers (P value = 0.01185). Significantly lower frequency of the A-C-C-G with higher frequency of A-C-A-G haplotypes was also noticed in subjects with DS (P value = 0.02089 and 0.00588 respectively). Data obtained indicate that the rs2073601 ‘A’ allele, responsible for nonsynonymous substitution of leucine to methionine, may have some role in DS in this population.

Importance of gene variants and co-factors of folate metabolic pathway in the etiology of idiopathic intellectual disability

Different components of the folate metabolic cycle are crucial for maintaining integrity of DNA. The present study was aimed at exploring the role of some important constituents of the folate cycle in the etiology of idiopathic intellectual disability (IID). Nuclear families with IID probands (n=226) and ethnically matched controls (n=181) were recruited for micronucleus, karyotype, genetic polymorphism (MTR rs1805087, MTRR rs1801394, and DHFR rs70991108), folate, vitamin B6, vitamin B12, and cysteine analysis. Significant difference in genotype frequencies in IID probands and their parents were observed for rs1805087 (P=0.03, 0.02), rs1801394 (P=0.03, 0.001), and rs70991108 ((P=0.03, 0.02) as compared to controls. IID probands showed significantly higher micronucleus frequency (P=0.01) and decreased vitamin B6 level (P=0.002). A strong correlation between rs1801394 'G' allele and micronucleus was also noticed. From the present investigation, a role of genetic polymorphisms and vitamin B6 levels could be hypothesized in the etiology of IID.

Association of XRCC1, XRCC3, and NAT2 polymorphisms with the risk of oral submucous fibrosis among eastern Indian population

BACKGROUND

Arecanut and smokeless tobacco usage is a major cause for oral submucous fibrosis (OSF) and its subsequent development to oral squamous cell carcinoma in South-east Asian population. Polymorphisms at N-acetyltransferase 2 locus, coding for an enzyme catalyzing acetylation of aromatic amines, might cause DNA adduct formation because of improper acetylation of these polyaromatic hydrocarbons. DNA repair enzymes remove these adduct to prevent malignancy.

METHODS

In this hospital-based study, 100 controls and 88 OSF patients were genotyped at four polymorphic sites on NAT2 481 (C > T; silent), 590 (G > A; Arg197 > Gln), 803 (A > G; Lys268 > Arg), 857 (G > A; Gly286 > Glu) and two on XRCC1 18067 (C > T Arg 194 > Trp), 28152 (G > A Arg 399 > Gln), and one of XRCC3 26304 (C > T Thr 241 > Met) loci by PCR-RFLP to determine the risk of the disease.

RESULTS

Heterozygous XRCC3 codon 241 [OR 2.07 (1.05-4.06)], homozygous variant of NAT C481T [OR 2.81 (1.09-7.21)], and both heterozygous and homozygous variants of NAT codon 268 and 286 [OR 2.31 (1.20-4.45) and 4.98 (1.87-13.14), and 6.12 (2.75-13.62) and 2.65 (1.04-6.72)] individually influenced susceptibility to OSF in the population.

CONCLUSION

Gene-gene interaction analysis by multifactor dimensionality reduction (MDR) revealed that XRCC3 Thr 241 Met had the largest univariate effect followed by XRCC3 Thr 241 Met - NAT2 A857G in men that presents a highly synergistic interaction as one of the potential combinations of single nucleotide polymorphisms (SNPs) to increase the risk of OSF in men if exposed to arecanut or smokeless tobacco usage. These observations can speculate the impact of the studied SNPs on the etiology of OSF.

Dopamine receptor D4 exon 3 variable number of tandem repeat polymorphism: Distribution in eastern Indian population

BACKGROUND:

A 48bp variable number of tandem repeat (VNTR), in the dopamine receptor D4 (DRD4), has been extensively studied in association with a variety of traits and neuropsychiatric disorders in different ethnic groups; the VNTR has been found to affect receptor binding.

AIMS:

This investigation, for the first time, compared distribution of DRD4 VNTR in different Indian populations from the eastern part of the country, belonging to Indo-Caucasoid and Indo-Mongoloid ethnicity.

MATERIALS AND METHODS:

852 individuals were recruited and divided into six population groups; Brahmin, Kayastha, Scheduled Caste, Mahishya, Muslim and Manipuri (Meitei). Allele and genotype frequencies were compared among groups as well as with data available for south-western Indian population.

RESULTS:

A total of six alleles (2-7-repeats) were observed, of which the 4-repeat (4R) was most frequent. Gross genetic dissimilarities were noticed between the Indo-Caucasoid and Indo-Mongoloid ethnic groups. Muslim group lacked 5R and 7R, while Manipuri group exhibited a very high frequency of 2R. Populations from eastern India revealed lower 7R frequencies as compared to the south-western populations.

CONCLUSIONS:

The DRD4 VNTR has been reported to play important role in cognition and alleles with higher repeats have been found to be associated with novelty seeking and personality traits. The present comparative analysis of different eastern Indian population would be helpful in extending our knowledge on this particular DRD4 variant. It will also be useful in understanding the behavioural differences between populations in the light of their genetic make up.

Role of SNAP25 explored in eastern Indian attention deficit hyperactivity disorder probands

Synaptosomal-associated protein 25 (SNAP25) is an essential component for synaptic vesicle mediated release of neurotransmitters. Deficiencies or abnormal structure or function of SNAP25 protein, possibly arising through genetic variations in the relevant DNA code, has been suggested to play role in the pathology of several neurobehavioural disorders including Attention deficit Hyperactivity Disorder (ADHD) and a number of polymorphisms in the SNAP25 gene has been studied for association with the disorder. In the present investigation, for the first time association between ADHD and six SNAP25 polymorphisms, rs1889189, rs362569, rs362988, rs3746544, rs1051312, and rs8636 was explored in eastern Indian population. Subjects were recruited following the Diagnostic and Statistical Manual for Mental Disorders-IV. Genomic DNA isolated from peripheral blood leukocytes of ADHD probands (n = 150), their parents (n = 272) and ethnically matched controls (n = 100) was used for amplifying target sites. Data obtained were subjected to population- as well as family-based analyses. While case-control analysis revealed lack of any significant difference for alleles, family-based studies revealed a mild over transmission rs3746544 'T' and rs8636 'C' alleles (P = 0.05 and 0.03 respectively). Haplotypes formed between rs362569 "T", 362988 "G", rs3746544 "T", rs1051312 "T" and rs8636 "C" in different combinations showed statistically significant transmission to ADHD probands. Excepting rs3746544 and rs8636, all the tested sites showed very low linkage disequilibrium between them. Data obtained in this preliminary study indicates that rs3746544 'T' allele may have some role in the disease etiology in the studied Indian population.

Role of functional dopaminergic gene polymorphisms in the etiology of idiopathic intellectual disability

Intellectual disability (ID) is of major concern throughout the world, though in ~40% of cases etiology remains unknown (idiopathic ID or IID). Cognitive impairment and behavioral problems are of common occurrence in these subjects and dopamine is known to play an important role in regulating these traits. In the present study the role of functional polymorphisms in three dopaminergic genes, dopamine receptor D4 (DRD4: exon3 VNTR and rs1800955), dopamine transporter (DAT1: 3'UTR VNTR and intron8 VNTR) and catechol-O-methyl transferase (COMT: rs4680 and rs165599), was explored in IID. Probands (n=225), parents (n=298) and ethnically matched controls (n=175) were recruited following DSM-IV. Genotype data obtained was used for population- and family-based statistical analyses. Population-based analysis showed significant association of DRD4 exon3 VNTR 6R allele (P=0.01), DAT1 3'UTR VNTR lower repeat (6R and 7R) alleles (P<0.02) and intron8 VNTR 5R allele (P=0.0012) with IID. Stratified analysis revealed significant association of these alleles (P<0.05) with IID individuals exhibiting severe behavioral problems. On the other hand, preferential transmission of COMT rs4680 A allele and A-A haplotype (P<0.05) was observed specifically in male IID probands without any behavioral problem. Markers failed to show any significant epistatic interaction by MDR analysis. Alleles showing positive association were all reported to confer suboptimal activity to the transcribed proteins. Therefore, an alteration in dopaminergic neurotransmission could be predicted that may lead to impairments in cognition and behavioral problems.

Role of gene-gene/gene-environment interaction in the etiology of eastern Indian ADHD probands

Associations between attention deficit hyperactivity disorder (ADHD) and genetic polymorphisms in the dopamine receptors, transporter and metabolizing enzymes have been reported in different ethnic groups. Gene variants may affect disease outcome by acting synergistically or antagonistically and thus their combined effect becomes an important aspect to study in the disease etiology. In the present investigation, interaction between ten functional polymorphisms in DRD4, DAT1, MAOA, COMT, and DBH genes were explored in the Indo-Caucasoid population. ADHD cases were recruited based on DSM-IV criteria. Peripheral blood samples were collected from ADHD probands (N=126), their parents (N=233) and controls (N=96) after obtaining informed written consent for participation. Genomic DNA was subjected to PCR based analysis of single nucleotide polymorphisms and variable number of tandem repeats (VNTRs). Data obtained was examined for population as well as family-based association analyses. While case-control analysis revealed higher occurrence of DAT1 intron 8 VNTR 5R allele (P=0.02) in cases, significant preferential transmission of the 7R-T (DRD4 exon3 VNTR-rs1800955) and 3R-T (MAOA-u VNTR-rs6323) haplotypes were noticed from parents to probands (P=0.02 and 0.002 respectively). Gene-gene interaction analysis revealed significant additive effect of DBH rs1108580 and DRD4 rs1800955 with significant main effects of DRD4 exon3 VNTR, DAT1 3'UTR and intron 8 VNTR, MAOA u-VNTR, rs6323, COMT rs4680, rs362204, DBH rs1611115 and rs1108580 thereby pointing towards a strong association of these markers with ADHD. Correlation between gene variants, high ADHD score and low DBH enzymatic activity was also noticed, especially in male probands. From these observations, an impact of the studied sites on the disease etiology could be speculated in this ethnic group.

Congenital pouch colon with unilateral renal agenesis and monorchism

BACKGROUND

Congenital pouch colon, also known as congenital short colon or "Pouch colon syndrome", is a rare condition that occurs in association with anorectal malformations; colon is either partially or completely replaced by pouch-like dilatation and communicates with the urogenital tract by means of a fistula. This anomaly is exclusively seen in Northern parts of India with only a few cases reported from elsewhere.

CASE PRESENTATION

A 1-day old neonate was presented with abdominal distension due to lack of passage of meconium. Clinical and radiological investigations revealed ano-rectal malformation. Incidental findings were left sided renal agenesis and right sided anorchia. Laparotomy revealed congenital pouch colon which was dealt accordingly. The baby is now healthy and awaiting further reconstructive surgery.

CONCLUSION

Although urogenital anomalies are not uncommon with congenital pouch colon, the finding of renal agenesis with unilateral anorchia is quite rare.

Prediction of feed intolerance and necrotizing enterocolitis in neonates with absent end diastolic flow in umbilical artery and the correlation of feed intolerance with postnatal superior mesenteric artery flow

OBJECTIVES

To evaluate the role of postnatal superior mesenteric artery (SMA) flow in predicting feed intolerance and NEC in the babies who had AEDF in comparison with gestation matched SGA and AGA with normal flow.

DESIGN

This was a prospective cohort study conducted in 62 eligible babies admitted in NICU. Babies were enrolled in 3 groups. Group 1 (n = 23) was SGA and AEDF, group 2 (n = 20) was SGA and group 3 (n = 19) was AGA and both with normal UA flow. In all babies baseline SMA flow was measured before test feed (0.5 ml) and repeated every 15 minutes for 1 hour after the feed.

RESULTS

Feed intolerance was seen in 69.5% of babies in group1 (p = <0.001) as compared to 20% and 17.5% in group 2 and 3. Four (17.3%) babies developed NEC in group1 (p = 0.02) but none in other 2 groups. Baseline peak systolic velocity (PSV) and time average mean velocity (TAMV) at 60 min post feed were significantly (p = 0.01 and 0.028 respectively) lower in group1 than group3. TAMV and PSV at 60 min post feed were significantly lower (p = 0.028 and 0.03) in babies with feed intolerance as compared to no feed intolerance group. Absent end diastolic flow and hypoglycemia were independent risk factors for feed intolerance.

CONCLUSION

SGA babies with AEDF had higher incidence of feed intolerance and NEC. Serial SMA flow studies specially the 60 min post feed study may help in differentiating which babies are likely to develop feed intolerance.

Screening of rural children in West Bengal for fragile-X syndrome

BACKGROUND & OBJECTIVE

Screening for Fragile X syndrome (FRAXA), the most common genetic cause for mental retardation (MR), has mostly been carried out among MR patients. The present study was conducted to find out prevalence of FRAXA amongst children residing in the rural areas of West Bengal.

METHODS

Demographic details including age, sex, nutritional status as well as birth, medical, and developmental histories, were collected amongst rural children (n=38,803) of West Bengal, India, over three years (2004-2007). Based on the records of scholastic backwardness, 179 children were short-listed and examined by a team of experts comprising of child psychiatrist, clinical psychologist, paediatrician and special educator. Blood samples were collected and molecular and cytogenetic studies were performed for identification of CGG repeats and determination of FMR1 gene promoter methylation.

RESULTS

Of the selected 179 children, six were diagnosed as Down syndrome, one as cerebral palsy and 140 as non-syndromic MR. These 140 children with MR were grouped as mild (56), moderate (60), and severely (4) retarded based on IQ; children <5 yr were grouped as developmental delay (20). FRAXA was not detected in any of these children (frequency being 0% with 0-.02% confidence interval). Prevalence of MR was found to be low (about 4/1000 children). Down syndrome also had a lower frequency (0.15/1000 children).

INTERPRETATION & CONCLUSION

The data obtained in the present study indicated that familial disorders like FRAXA were less frequent in the studied population.

Clinical risk factors associated with extubation failure in ventilated neonates

We conducted this study to find out the incidence of extubation failure (EF) in ventilated neonates and associated clinical risk factors. Eighty two ventilated neonates were followed up to 48 hours post extubation to look for EF. Twenty two babies (26.8%) had EF. The common risk factors for EF were presence of patent ductus arteriosus, post-extubation lung collapse and acquired pneumonia. The duration of ventilation, and maximum and pre-extubation alveolar arterial oxygen gradients (AaDO2) were significantly higher (P<0.05) in EF group. The incidence of sepsis (P=0.034), anemia (P=0.004) and pneumonia (P=0.001) were significantly higher in EF group. Detection of significant PDA and adequate post extubation care may help to reduce rate of extubation failure in neonates.