Table 1 Genetic association studies directed at identifying risk factors for adult ADHD or influencing adult ADHD severitya (studies in adolescents were not included in the selection)
From: The genetics of attention deficit/hyperactivity disorder in adults, a review
Name of gene | Gene symbol | Polymorphism investigated | Type of analysis | Sample investigated | Findings | Reference |
|---|---|---|---|---|---|---|
Dopaminergic genes | ||||||
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 3=dopamine transporter | SLC6A3/DAT1 | 40 bp VNTR in 3′-UTR | ANOVA, qualitative and quantitative FBAT | 152 cases; 102 families (72 overlapping with case study; 45 triads, 36 pairs, 16 multiple sib families, 5 multigeneration families) | No association | Muglia et al.40 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 3=dopamine transporter | SLC6A3/DAT1 | 40 bp VNTR in 3′-UTR | Case–control | 122 hyperactive, 67 controls, followed to adulthood | 9/10 genotype more symptoms (P=0.01) and more impairment (work performance (P=0.02), grade point average (P=0.04)) than 10/10 genotype, more omission errors on a continuous performance test | Barkley et al.41 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 3=dopamine transporter | SLC6A3/DAT1 | 40 bp VNTR in 3′-UTR; 30 bp VNTR in intron 8 | Case–control | 122 cases, 174 controls | No association of single VNTRs or haplotype | Bruggemann et al.42 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 3=dopamine transporter | SLC6A3/DAT1 | 40 bp VNTR in 3′-UTR | Case–control | 358 cases, 340 controls | No association | Johansson et al.43 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 3=dopamine transporter | SLC6A3/DAT1 | 40 bp VNTR in 3′-UTR; 30 bp VNTR in intron 8 | Case–control | 216 cases, 528 controls | Association of 9-6 haplotype with ADHD diagnosis (P=0.0011) | Franke et al.44 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 3=dopamine transporter | SLC6A3/DAT1 | 40 bp VNTR in 3′-UTR; 30 bp VNTR in intron 8 | Case–control/meta-analysis | 1440 cases, 1769 controls | Association of 9-6 haplotype with ADHD diagnosis (P=0.03), association of 9/9 genotype with ADHD diagnosis (P=0.03) | Franke et al.45 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 3=dopamine transporter | SLC6A3/DAT1 | 40 bp VNTR in 3′-UTR | Case–control | 102 cases, 479 controls | No association | da Silva et al.46 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 3=dopamine transporter | SLC6A3/DAT1 | 40 bp VNTR in 3′-UTR | Case–control | 53 cases, 38 controls | Association of 9-repeat (9R) allele carriership with ADHD diagnosis (P=0.004), marginal association of 9R with working memory-related brain activity | Brown et al.47 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 3=dopamine transporter; dopamine receptor D4 | SLC6A3/DAT1, DRD4 | 40 bp VNTR in 3′-UTR of SLC6A3/DAT1, 48 bp VNTR in exon 3 of DRD4 | Cox proportional hazard models | ADHD cases and family members (n=563) | By 25 years of age, 76% of subjects with a DRD4 7-repeat allele were estimated to have significantly more persistent ADHD compared with 66% of subjects without the risk allele. No effect of DAT1 | Biederman et al.48 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 3=dopamine transporter; dopamine β-hydroxylase; dopamine receptor D4; dopamine receptor D5 | SLC6A3/DAT1, DBH, DRD4, DRD5 | SLC6A3/DAT1 40 bp VNTR in 3′-UTR; DBH TaqI SNP in intron 5 (rs2519152); DRD4 48 bp VNTR in exon 3 and 120 bp VNTR in promoter; DRD5 (CA)n repeat 18.5 kb from the start codon of gene | Regression analysis, taking life events and personality factors into account | 110 cases | No effects of genes on ADHD severity | Müller et al.49 |
Dopamine receptor D4; solute carrier family 6 (neurotransmitter transporter, dopamine), member 3=dopamine transporter | DRD4, SCL6A3/DAT1 | DRD4 48 bp VNTR in exon 3 and 120 bp ins/del in promoter; SLC6A3/DAT1 40 bp VNTR in 3′ UTR and 30 bp VNTR in intron 8 | Case–control/meta-analysis | 1608 cases, 2358 controls | Nominal association (P=0.02) of the L-4R haplotype (dup120–48 bp VNTR) with aADHD, especially with the combined clinical subtype. No interaction with DAT1 haplotype | Sanchez-Mora et al.50 |
Dopamine receptor D4 | DRD4 | 48 bp VNTR in exon 3 | Case–control, TDT, combination | 66 cases, 66 controls; 44 families (29 triads, 14 pairs); combination of all cases (n=110) | Evidence for association in case–control (P=0.01) and combined sample (P=0.003) (7R vs non-7R alleles) | Muglia et al.51 |
Dopamine receptor D4 | DRD4 | 48 bp VNTR in exon 3 and 120 bp ins/del in promoter | Association/linkage (PDT) | 14 multigeneration families from genetic isolate (Colombia), children and adults affected | 7R allele of 48 bp VNTR (P=0.0578), haplotype of 7R-240 bp allele overtransmitted (P=0.0467) | Arcos-Burgos et al.52 |
Dopamine receptor D4 | DRD4 | 48 bp VNTR in exon 3 | Model fitting on Temperament/Character Inventory (TCI) and DRD4 genotype | 171 subjects from 96 families (=parents of ADHD sib pairs; 33% with lifetime ADHD, 15% with current ADHD) | DRD4 correlates with ADHD symptoms (r2=0.05), but not with novelty seeking (7R vs non-7R genotypes) | Lynn et al.53 |
Dopamine receptor D4 | DRD4 | 48 bp VNTR in exon 3 | Case–control | 122 hyperactive, 67 controls, followed to adulthood | No association | Barkley et al.41 |
Dopamine receptor D4 | DRD4 | 48 bp VNTR in exon 3 | Case–control | 358 cases, 340 controls | No association | Johansson et al.43 |
Dopamine receptor D3 | DRD3 | rs6280 (Ser9Gly) | TDT | 39 families (25 triads, 14 pairs) | No association | Muglia et al.54 |
Dopamine receptor D3 | DRD3 | rs2399504, rs7611535, rs1394016, rs6280 (Ser9Gly), rs167770, rs2134655, rs2087017 | Regression analysis | 60 binge eating disorder cases, 60 obese and 60 non-obese controls assessed for adult ADHD symptoms | Haplotypes containing the Ser9 allele higher hyperactive/impulsivity scores compared with those containing Gly9 for a haplotype window containing rs1394016 and Ser9Gly (global P=0.00038), as well as that containing Ser9Gly and rs167770 (global P=0.00017) | Davis et al.55 |
Dopamine receptor D2 | DRD2 | rs1800497 (TaqIA C>T) | Case–control | 85 alcoholics, 32.9% diagnosed with ADHD | No association | Kim et al.56 |
Dopamine receptor D2 | DRD2 | rs1800497 (TaqIA C>T) | ANOVA, comparison between patients with autism (ASD) and ADHD, with and without substance use disorders | 49 ADHD cases, 61 ASD patients | No association | Sizoo et al.57 |
Dopamine receptor D5 | DRD5 | (CA)n repeat 18.5 kb from the start codon of gene | TDT, case–control | 119 families with adult ADHD probands; 88 cases, 88 controls | Nonsignificant trend for association between the 148 bp allele and ADHD (P=0.055); excess of non-transmissions was detected for the 150 bp (P=0.023) and 152 bp (P=0.028) alleles; quantitative analyses for 150 bp allele with lower scores (lowest P=0.008) | Squassina et al.58 |
Dopamine receptor D5 | DRD5 | (CA)n repeat 18.5 kb from the start codon of gene | Case–control | 358 cases, 340 controls | Nominally significant association with adult ADHD (P=0.04), trend toward increased risk for 148 bp allele; strongest association with combined and inattentive subtypes (P=0.02; OR=1.27) | Johansson et al.43 |
Dopamine β-hydroxylase | DBH | TaqI SNP in intron 5 (rs2519152) | TDT, case–control | 97 triads; 112 cases, matched controls | Borderline significance in case–control comparison (P=0.057), risk allele under-represented in cases | Inkster et al.59 |
Dopamine β-hydroxylase | DBH | TaqI SNP in intron 5 (rs2519152) | Case–control | 122 hyperactive children, 67 controls, followed to adulthood | Adult A2 allele homozygotes take more risk in Card playing task (P=0.021) | Barkley et al.41 |
Dopamine β-hydroxylase | DBH | rs1611115 (−1021C>T) | Case–control, regression analysis | Four independent samples: healthy volunteers (n=387), patients with affective disorders (n=182), adult (ADHD cases (n=407), patients with personality disorders (n=637) | No association with ADHD (or other psychiatric diagnoses); association with neuroticism in ADHD, and conscientiousness in combined analysis of ADHD+personality disorder samples | Hess et al.60 |
Catechol O-methyl transferase | COMT | rs4680 (Val158Met) | Regression analysis | 203 healthy subjects assessed with ASRS for adult ADHD symptoms | Association of Val with inattention (P=0.008), hyperactivity/impulsivity (P=0.039) and total ASRS scale (P=0.006), highest scores Met/Met | Reuter et al.69 |
Catechol O-methyl transferase | COMT | rs4680 (Val158Met) | Case–control | 85 alcoholics, 32.9% diagnosed with ADHD | No association | Kim et al.56 |
Catechol O-methyl transferase | COMT | rs4680 (Val158Met) | Regression analysis | 110 cases | No association | Müller et al.61 |
Catechol O-methyl transferase | COMT | rs4680 (Val158Met), rs4818 | Regression analysis | 184 men referred for psychiatric examination, frequency of adult ADHD unclear | No association with ADHD, no gene–environment interaction with psychosocial adversity in childhood; nominal association with ADHD scores of combination of two haplotypes of SLC6A4 and COMT | Retz et al.62 |
Catechol O-methyl transferase | COMT | rs6269, rs4633, rs4818, rs4680 (Val158Met) | Regression analysis | 435 cases, 383 controls | Trend for association with hyperactivity/impulsivity scores for all markers, peaking at marker rs6269 (P=0.007); haplotype analysis showed association of suggested high COMT-activity haplotype with highest hyperactivity/impulsivity score (P=0.01) | Halleland et al.63 |
Serotonergic genes | ||||||
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 4=serotonin transporter | SLC6A4/5-HTT | 5-HTTLPR | Case–control | 30 (of 314) alcoholics with ADHD+anti-social personality disorder vs alcoholics without comorbidity vs matched controls | No association | Johann et al.64 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 4=serotonin transporter | SLC6A4/5-HTT | 5-HTTLPR | Case–control | 312 cases, 236 controls | No association with ADHD; nominal association with higher inattention and novelty-seeking scores, and a higher frequency of drug dependence | Grevet et al.65 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 4=serotonin transporter | SLC6A4/5-HTT | 5-HTTLPR | Case–control | 85 alcoholics, 32.9% diagnosed with ADHD | No association | Kim et al.56 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 4=serotonin transporter | SLC6A4/5-HTT | 5-HTTLPR | Regression analysis | 184 men referred for psychiatric examination, frequency of adult ADHD unclear | L/L genotype associated with persistent ADHD (P=0.047); gene–environment interaction: carriers of at least one S allele are more sensitive to childhood environment adversity than carriers of L/L (P=0.025) | Retz et al.62 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 4=serotonin transporter | SLC6A4/5-HTT | 5-HTTLPR; rs25531 in LPR | Regression analysis | 110 cases | Taking into account stressors, the L allele showed association with increased ADHD severity, particularly as regard affective dysregulations (P=0.002); in subjects exposed to early stressors, the L allele showed a protective effect compared with the S allele (P=0.003) | Müller et al.61 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 4=serotonin transporter | SLC6A4/5-HTT | 5-HTTLPR and seven tag-SNPs in discovery sample; 5-HTTLPR and one SNP in meta-analysis | Case–control | 448 patients and 580 controls in discovery sample, 1894 patients and 1977 controls in meta-analysis | Association with rs140700 (P=0.00084, in women) and S allele of the 5-HTTLPR (P=0.06) in discovery; only S allele associated with adult ADHD at P=0.06 in replication. Potential findings for rare variants | Landaas et al.66 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 4=serotonin transporter | SLC6A4/5-HTT | 5-HTTLPR | Regression analysis, gene–environment interaction | 123 cases with adult ADHD (and 183 patients suffering from personality disorders) | No association with adult ADHD, no G × E effects | Jacob et al.67 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 4=serotonin transporter | SLC6A4/5-HTT | 5-HTTLPR | Cox proportional hazard models | ADHD cases and family members (n=563) | No effect of 5-HTT | Biederman et al.48 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 4=serotonin transporter; tryptophan hydroxylase 2 | SLC6A4/5-HTT, TPH2 | 5-HTTLPR in SLC6A4/5-HTT, rs1843809 in TPH2 | ANOVA, comparison between patients with autism (ASD) and ADHD, with and without substance use disorders | 49 ADHD cases, 61 ASD patients | Carriership of G-allele of TPH2 rs1843809 and of L-allele of the 5-HTTLPR was less frequent in ADHD compared with ASD patients (P=0.041 and 0.04, respectively) | Sizoo et al.57 |
Serotonin receptors 1A, 1B, 1D, 1E, 1F, 2A, 2B, 2C, 3A, 3B, 4, 5A, 6, 7; solute carrier family 6 (neurotransmitter transporter, dopamine), member 4=serotonin transporter; tryptophan hydroxylase 1; dopa decarboxylase; monoamine oxidase A, B | HTR1A, HTR1B, HTR1D, HTR1E, HTR1F, HTR2A, HTR2B, HTR2C, HTR3A, HTR3B, HTR4, HTR5A, HTR6, HTR7, SLC6A4/5-HTT, TPH1, DDC, MAOA, MAOB | 132 tag-SNPs | Case–control | 188 adult cases (+263 children), 400 controls | DDC: associated with adult (lowest P=00053, OR 2.17) and childhood ADHD; MAOB: associated with adult ADHD (lowest P=0.0029, OR 1.9); HTR2A: association with combined subtype in adults (lowest P=0.0036, OR 1.63) and children | Ribases et al.68 |
Serotonin receptor 2A | HTR2C | Cys23Ser | Case–control | 30 (of 314) alcoholics with ADHD+anti-social personality disorder vs alcoholics without comorbidity vs matched controls | No association | Johann et al.64 |
Serotonin receptor 2A | HTR2A | 102T>C | Regression analysis | 203 healthy subjects assessed with ASRS for adult ADHD symptoms | Association of C allele with hyperactivity/impulsivity (P=0.020) and total ASRS scale (P=0.042), highest scores in T/T genotype | Reuter et al.69 |
Serotonin receptor 2A | HTR2A | rs6314 (His452Tyr) | Regression analysis, taking life events and personality factors into account | 110 cases | No effects of genes on ADHD severity | Müller et al.49 |
Serotonin receptor 1A | HTR1A | rs6295 | Regression analysis, gene–environment interaction | 123 cases with adult ADHD (and 183 patients suffering from personality disorders) | Decrease the risk of anxious–fearful cluster C personality disorders in adult ADHD (P=0.016) | Jacob et al.67 |
Tryptophan hydroxylase 2 | TPH2 | rs4570625 | Regression analysis, gene–environment interaction | 123 cases with adult ADHD (and 183 patients suffering from personality disorders) | No association with adult ADHD, no G × E effects | Jacob et al.67 |
Tryptophan hydroxylase 2 | TPH2 | 18 SNPs in discovery sample, 5 SNPs in meta-analysis | Regression analysis; meta-analysis | 1636 cases, 1923 controls in meta-analysis | TPH1: nominal association for rs17794760; TPH2: no association | Johansson et al.70 |
Tryptophan hydroxylase 1 | TPH1 | 9 SNPs in discovery sample, 1 SNP (rs17794760) in meta-analysis | ||||
Noradrenergic genes | ||||||
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 2=norepinephrine transporter | SLC6A2/NET1 | rs998424 (intron 9) | ANOVA, qualitative and quantitative FBAT | 128 triads | No association | De Luca et al.71 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 2=norepinephrine transporter | SLC6A2/NET1 | rs5569, rs998424, rs2242447 | Regression analysis | 184 men referred for psychiatric examination, frequency of adult ADHD unclear | No association with ADHD, no gene–environment interaction with psychosocial adversity in childhood; nominal association with ADHD scores of combination of two haplotypes of SLC6A4 and COMT | Retz et al.62 |
Solute carrier family 6 (neurotransmitter transporter, dopamine), member 2=norepinephrine transporter | SLC6A2/NET1 | rs998424 (intron 9) | Regression analysis | 110 cases | No association | Müller et al.61 |
Adrenergic α-2A-receptor | ADRA2A | rs1800544, rs1800544, rs553668 | Case–control | 403 cases, 232 controls | No association | de Cerqueira et al.72 |
Adrenergic α-2C-receptor | ADRA2C | (TG)n 15 kb upstream of start codon | TDT | 128 triads | No association (TG16 and TG17 alleles) | De Luca et al.71 |
Neurotrophic genes | ||||||
Nerve growth factor; brain-derived neurotrophic factor; neurotrophin 3; neurotrophin 4/5; ciliary neurotrophic factor; neurotrophic tyrosine kinase, receptor, types 1, 2, 3; nerve growth factor receptor; ciliary neurotrophic factor receptor | NGF, BDNF, NTF3, NTF4/5, CNTF, NTRK1, NTRK2, NTRK3, NGFR, CNTFR | 183 tag-SNPs | Case–control | 216 adults (330 children), 546 controls | Single-marker and haplotype-based association of CNTFR and both adulthood (lowest P=0.0077, OR=1.38) and childhood ADHD | Ribases et al.89 |
Neurotrophin 3; neurotrophic tyrosine kinase, receptor, types 2, 3; brain-derived neurotrophic factor; nerve growth factor receptor | NTF3, NTRK2, NTRK3, BDNF, NGFR | NTF3 rs6332 and rs4930767, NTRK2 rs1212171, NTRK3 rs1017412, BDNF rs6265 (Val66Met), p75(NTR) rs2072446 | Regression analysis | 143 men referred for psychiatric examination, frequency of adult ADHD unclear | Exonic NTF3 variant (rs6332) showed nominal trend toward association with increased scores of retrospective childhood analysis Wender–Utah Rating Scale (WURS-k) (P=0.05) and adult ADHD assessment Wender–Reimherr interview (P=0.03) | Conner et al.74 |
Brain-derived neurotrophic factor | BDNF | rs6265 (Val66Met) | Case–control/meta-analysis, regression analysis | 1445 cases, 2247 controls | No association | Sanchez-Mora et al.75 |
Brain-derived neurotrophic factor | BDNF | rs6265, rs4923463, rs2049045, rs7103411 | Regression analysis, taking life events and personality factors into account | 110 cases | No effects of genes on ADHD severity | Müller et al.49 |
Brain-derived neurotrophic factor; lin-7 homolog A | BDNF, LIN-7 | rs4923463, rs6265 (Val66Met), rs11030104, rs2049045 and rs7103411 in BDNF; rs10835188 and rs3763965 in LIN-7 | TDT, case–control | 80 trios of adult ADHD proband and parents; 121 cases, 121 controls | BDNF Val66Met, BDNF rs11030104, LIN-7 rs10835188 associated with ADHD in combined analysis | Lanktree et al.76 |
Others | ||||||
Protein kinase, cGMP-dependent, type I | PRKG1 | 2276C>T | TDT | 63 informative nuclear families | No association | De Luca et al.77 |
Cholinergic receptor, nicotinic, α7; protein kinase, cGMP-dependent, type I; trace amine-associated receptor 9 | CHRNA7, PRKG1, TAAR9 | CHRNA7 D15S1360; PRKG1 2276C>T; TAAR9 181A>T | Regression analysis, taking life events and personality factors into account | 110 cases | No effects of genes on ADHD severity | Müller et al.49 |
Clock homolog | CLOCK | rs1801260, 3′-UTR | Regression analysis | 143 men referred for psychiatric examination, frequency of adult ADHD unclear | Association of genotypes with at least one T allele with self-reported and interview ADHD scores (lowest P=0.00002) | Kissling et al.78 |
Aldehyde dehydrogenase 2 family (mitochondrial) | ALDH2 | SNP, identity unclear | Case–control | 85 alcoholics, 32.9% diagnosed with ADHD | No association | Kim et al.56 |
Cannabinoid receptor 1 | CNR1 | 4 tag-SNPs | Relevant for adult ADHD: case–control | Unselected adolescent sample and family-based sample of trios (ADHD child plus parents). Trio parents (with and without ADHD) used as additional case–control sample of adults (n=320; 46% affected) | Association with childhood ADHD, but no association with adult ADHD | Lu et al.79 |
Nitric oxide synthase 1 | NOS1 | Ex1f VNTR | Case–control | Personality disorder cases (n=403), adult ADHD (n=383), familial ADHD (n=151), suicide attempters (n=189), criminal offenders (n=182), controls (n=1954) | Short variant more frequent in adult ADHD (P=0.002), cluster B personality disorder (P=0.01), autoaggressive (P=0.02)/heteroaggressive (P=0.04) behavior | Reif et al.80 |
Latrophilin 3 | LPHN3 | Different sets, rs6551665, rs1947274 and rs2345039 were investigated in the largest sample | Case–control | 2627 (childhood and adult) ADHD cases and 2531 controls | rs6551665 (P=0.000346), rs1947274 (P=0.000541) and rs2345039 (P=0.000897) were significant after correction for multiple testing | Arcos-Burgos et al.81 |
Latrophilin 3 | LPHN3 | 44 SNPs tagging the gene | Case–control | 334 cases, 334 controls | rs6858066: P=0.0019, OR=1.82 (1.25-2.70); three-marker haplotype (rs1868790/rs6813183/rs12503398): P=5.1e-05, OR=2.25 (1.52–3.34) for association with combined ADHD | Ribases et al.82 |
BAI1-associated protein 2; dapper, antagonist of β-catenin, homolog 1; LIM domain only 4; neurogenic differentiation 6; ATPase, Ca 2+ transporting, plasma membrane 3; inhibitor of DNA binding 2, dominant negative helix–loop– helix protein | BAIAP2, DAPPER1, LMO4, NEUROD6, ATP2B3, ID2 | 30 tag-SNPs | Case–control | Exploration sample: 270 adults (317 children), 587 controls; replication samples: 639 adult ADHD cases, 612 controls and 417 adult ADHD cases, 469 controls | Single- and multiple-marker analysis showed association of BAIAP2 with adult ADHD (P=0.0026 and 0.0016, respectively); replication in the larger one of the two replication samples (P=0.0062) | Ribases et al.73 |
Calcium channel, voltage-dependent, L-type, α 1C subunit; ankyrin 3, node of Ranvier (ankyrin G); myosin VB; tetraspanin 8; zinc-finger protein 804A | CACNA1C, ANK3, MYO5B, TSPAN8 and ZNF804A | ZNF804A rs1344706, ANK3 rs9804190 and rs10994336, CACNA1C rs1006737, TSPAN8 rs1705236, MYO5B rs4939921 | Regression analysis | 561 ADHD cases, 711 controls | No association | Landaas et al.83 |
Contactin-associated protein-like 2; cadherin 13 | CNTNAP2, CDH13 | rs7794745 in CNTNAP2, rs6565113 in CDH13 | ANOVA, comparison between patients with autism (ASD) and ADHD, with and without substance use disorders | 49 ADHD cases, 61 ASD patients | Carriership of T-allele of the CNTNAP2 rs7794745 polymorphism more often present in the ADHD group compared with the ASD group (P=0.025) | Sizoo et al.57 |
