[Association between serotonin 1D gene polymorphisms and attention deficit hyperactivity disorder comorbid or not comorbid learning disorder].

OBJECTIVE: To investigate the relationship between two HTR1D gene polymorphisms, 1350T>C and 1236A>G polymorphisms, and attention deficit hyperactivity disorder (ADHD) comorbid or not comorbid learning disorder (LD). METHODS: Blood samples were taken from 91 trios with probands of ADHD comorbid LD and 181 trios with probands of ADHD not comorbid LD. DNA was extracted. 1350T>C and 1236A>G were genotyped by restriction fragment length polymorphism analysis. Transmit/disequilibrium test and haplotype analysis were used to test the association between the two polymorphisms of HTR1D gene and ADHD comorbid or not comorbid LD separately. RESULTS: 1236A allele (chi2=5.306, P=0.021) was over transmitted to probands of ADHD without LD. No biased transmissions of any allele and haplotype were found in families with probands of ADHD with LD. CONCLUSION: whether ADHD comorbid LD or not comorbid LD makes difference at the level of HTR1D gene polymorphism of 1236A>G.

[Association between serotonin 2C gene polymorphisms and attention deficit hyperactivity disorder in children with or without comorbidity of disruptive behavior disorder].

OBJECTIVE: Disruptive behavior disorder (DBD) is one of the main comorbidity of attention deficit hyperactivity disorder (ADHD). Previous studies showed significantly different serotonin function between ADHD children with and without the comorbidity of DBD. Therefore, it is needed to compare these two groups in terms of serotonin receptor gene polymorphisms, which may provide further evidence for the previous studies. The current study aimed to investigate the relationship between two serotonin receptor 2C (HTR2C) gene polymorphisms, that are C-759T and G-697C polymorphisms, and ADHD with or without concomitant DBD. METHOD: Blood samples were taken from 237 trios with probands of ADHD with DBD comorbidity and 251 trios with probands of ADHD without comorbidity of DBD. All the subjects were from the ADHD clinic of Peking University Sixth Hospital. DNA was extracted and PCR was performed to amplify the fragments containing both C-759T and G-697C polymorphisms. AciI was used to detect different alleles of the two polymorphisms. Both allele-based and haplotype-based TDT analyses were used to test the association of the two polymorphisms of HTR2C gene and ADHD with or without comorbidity of DBD. RESULTS: The haplotypes -759C (chi(2) = 4.25, P = 0.04), -697G(chi(2) = 3.21, P = 0.07), as well as -759C/-697G were over-transmitted (chi(2) = 4.31, P = 0.04) to the probands of ADHD without DBD. No biased transmission of any allele and haplotype were found in families with probands of ADHD with DBD. CONCLUSION: ADHD with or without the comorbidity DBD was different at the level of HTR2C gene polymorphisms of C-759T and G-697C. HTR2C is related to ADHD without DBD, while not related to ADHD with DBD. The results suggested that the two groups may have different genetic background, at least in HTR2C.

[Association between serotonin 4 gene polymorphisms and attention deficit hyperactivity disorder comorbid or not comorbid disruptive behavioral disorder].

OBJECTIVE: To investigate the relationship between three HTR4 gene polymorphisms, 83097 C>T, 83198 A>G as well as -36C>T polymorphisms, and attention deficit hyperactivity disorder (ADHD) comorbid or not comorbid disruptive behavioral disorder (DBD). METHODS: Blood samples were taken from 152 trios with probands of ADHD comorbid DBD and 173 trios with probands of ADHD not comorbid DBD. DNA was extracted. 83097 C>T, 83198 A>G and -36C>T were genotyped by restriction fragment length polymorphism analysis. Transmit/disequilibrium test and haplotype analysis were used to test the association of the three polymorphisms with ADHD comorbid or not comorbid DBD separately. RESULTS: Haplotype T/G/T showed tendency of over transmission (chi(2)=3.470,P=0.062) to probands of ADHD with DBD, while haplotype C/G/T (chi(2)=4.568,P=0.032) and C/G/C (chi(2)=5.333,P=0.021) were under transmitted to probands of ADHD without DBD, No biased transmissions of any allele were found in families with probands of ADHD with and without DBD. CONCLUSION: Whether ADHD comorbid DBD or not comorbid DBD makes difference at the level of HTR4 gene polymorphisms.

[Association between serotonin 1D gene polymorphisms and attention deficit hyperactivity disorder comorbid or not comorbid disruptive behavior disorder].

OBJECTIVE: To investigate the relationship between two HTR1D gene polymorphisms, that is 1350T > C and 1236A > G polymorphisms, and attention deficit hyperactivity disorder (ADHD) comorbid or not comorbid disruptive behavior disorder (DBD). METHODS: Blood samples were taken from 90 trios with probands of ADHD comrbid DBD and 182 trios with probands of ADHD not comorbid DBD. DNA was extracted. 1350T > C and 1236A > G were genotyped by restriction fragment length polymorphism analysis. Transmit/disequilibrium test and haplotype analysis were used to test the association of the two polymorphisms of HTR1D gene and ADHD comorbid or not comorbid disruptive behavior disorder (DBD) separately. RESULTS: 1350T allele(chi2 = 3.67, P = 0.055)and G/T haplotype(chi2 = 3.84, P = 0.050)were overtransmitted, while 1350C allele(chi2 = 3.67, P = 0.055) and G/C haplotype(chi2 = 5.22, P = 0.022)were undertransmitted to probands of ADHD with DBD. No biased transmission of any allele and haplotype was found in families with probands of ADHD without DBD. CONCLUSION: ADHD comorbid or not comorbid DBD are different at the level of HTR1D gene polymrohisms of 1350T > C and 1236A > G. The current results indicate that ADHD with DBD has more heritable backgrounds when compared with ADHD without DBD.

[Association studies of G352A polymorphism of dopamine transporter gene in Han Chinese attention deficit hyperactivity disorder patients].

OBJECTIVE: To investigate association of the new polymorphism G352A in the dopamine transporter gene (DAT1) exon 15 with attention deficit hyperactivity disorder (ADHD) in Han Chinese children. METHODS: The new mutant polymorphism G352A in the dopamine transporter gene (DAT1) exon 15 was found by the fluorescently-labeled dye-terminators assay. The study samples were comprised of 337 ADHD children, 207 unrelated controls and 201 integrated ADHD trios (included proband and biological parents). Associations of polymorphisms with ADHD and its subtypes were examined by: (i) comparing cases and controls; and (ii) using family-based association study in transmission-disequilibrium test (TDT). RESULTS: The allele frequencies at the DAT1 G352A locus in the control samples were 79.5% for 352G and 20.5% for 352A respectively. Association studies revealed no association between G352A in exon 15 of DAT1 and ADHD. But after a stratification by gender, there was possible association between G352A and ADHD girls: the 352G allele had a tendency to be preferentially transmitted to ADHD girls. CONCLUSION: There is no association between G352A, the new polymorphism, in exon 15 of DAT1 and ADHD. The 352G allele has a tendency to be preferentially transmitted to ADHD girls, but the findings require replication before drawing a definitive conclusion.

[Association between serotonin 2C gene polymorphisms and attention deficit hyperactivity disorder comorbid or not comorbid with learning disorder].

OBJECTIVE: To investigate the relationship between two HTR2C gene polymorphisms, that is C-759T and G-697C polymorphisms, and attention deficit hyperactivity disorder (ADHD) comorbid or not comorbid learning disorder (LD). METHODS: Blood samples were taken from 189 trios with probands of ADHD comorbid LD (ADHD+LD) and 299 trios with probands of ADHD not comorbid LD (ADHD-LD). DNA was extracted and PCR was performed to amplify the fragments containing both C-759T and G-697C polymorphisms. Aci I was used to detect different alleles of the two polymorphisms. Allele- based and haplotype- based TDT analysis were used to test the association of the two polymorphisms of HTR2C gene and ADHD-LD and ADHD+LD. RESULTS: -759C(chi(2)=6.961, P=0.008), -697G(chi(2)=8.346, P=0.004), as well as -759C/-697G haplotype were over- transmitted(chi(2)=9.000, P=0.002 7), while haplotype -759T/-697C was under- transmitted(chi(2)=7.784, P=0.005 3) to probands with ADHD-LD. No biased transmission of any allele and haplotype were found in families with probands of ADHD+LD. CONCLUSION: ADHD-LD and ADHD+LD are different at the level of HTR2C gene polymrohisms of C-759T and G-697C. HTR2C is related to ADHD-LD, while not related to ADHD+LD.

[Association between tryptophan hydroxylase gene polymorphisms and attention deficit hyperactivity disorder with or without learning disorder].

OBJECTIVE: To investigate the relationship between two tryptophan hydroxylasec (TPH) gene polymorphisms, A218C and A-6526G polymorphisms, and attention deficit hyperactivity disorder (ADHD) with or without learning disorder (LD). METHODS: Blood samples were taken from 132 trios with probands of ADHD with LD and 221 trios with probands of ADHD without LD. DNA was extracted and PCR was performed to amplify the fragments of A218C amd A-6526G polymorphisms. NheI and MboI were used to detect different alleles of the two polymorphisms separately. transmission disequilibriumtest (TDT) and haplotype analysis were used to test the association of the two polymorphisms of TPH gene and ADHD with or without LD. RESULTS: Haplotype block composed by A218C and A-6526G polymorphisms was related to ADHD with LD (chi(2) = 9.362, df = 3, P = 0.025). The haplotype of 218A/-6526G was significantly untransmitted to the probands with ADHD with LD (chi(2) = 9.252, df = 1, P = 0.002). CONCLUSION: TPH gene and the haplotype of 218A/-6526G may be related to ADHD with LD.