Maternal transmission of a rare GABRB3 signal peptide variant is associated with autism.

Maternal 15q11-q13 duplication is the most common copy number variant in autism, accounting for ∼1-3% of cases. The 15q11-q13 region is subject to epigenetic regulation, and genomic copy number losses and gains cause genomic disorders in a parent-of-origin-specific manner. One 15q11-q13 locus encodes the GABA(A) receptor ß3 subunit gene (GABRB3), which has been implicated by several studies in both autism and absence epilepsy, and the co-morbidity of epilepsy in autism is well established. We report that maternal transmission of a GABRB3 signal peptide variant (P11S), previously implicated in childhood absence epilepsy, is associated with autism. An analysis of wild-type and mutant ß3 subunit-containing α1ß3γ2 or α3ß3γ2 GABA(A) receptors shows reduced whole-cell current and decreased ß3 subunit protein on the cell surface due to impaired intracellular ß3 subunit processing. We thus provide the first evidence of an association between a specific GABA(A) receptor defect and autism, direct evidence that this defect causes synaptic dysfunction that is autism relevant and the first maternal risk effect in the 15q11-q13 autism duplication region that is linked to a coding variant.

Interaction of prenatal exposure to cigarettes and MAOA genotype in pathways to youth antisocial behavior.

Genetic susceptibility to antisocial behavior may increase fetal sensitivity to prenatal exposure to cigarette smoke. Testing putative gene x exposure mechanisms requires precise measurement of exposure and outcomes. We tested whether a functional polymorphism in the gene encoding the enzyme monoamine oxidase A (MAOA) interacts with exposure to predict pathways to adolescent antisocial behavior. We assessed both clinical and information-processing outcomes. One hundred seventy-six adolescents and their mothers participated in a follow-up of a pregnancy cohort with well-characterized exposure. A sex-specific pattern of gene x exposure interaction was detected. Exposed boys with the low-activity MAOA 5' uVNTR (untranslated region variable number of tandem repeats) genotype were at increased risk for conduct disorder (CD) symptoms. In contrast, exposed girls with the high-activity MAOA uVNTR genotype were at increased risk for both CD symptoms and hostile attribution bias on a face-processing task. There was no evidence of a gene-environment correlation (rGE). Findings suggest that the MAOA uVNTR genotype, prenatal exposure to cigarettes and sex interact to predict antisocial behavior and related information-processing patterns. Future research to replicate and extend these findings should focus on elucidating how gene x exposure interactions may shape behavior through associated changes in brain function.

Induction chemotherapy and concurrent chemoradiotherapy for locoregionally advanced head and neck cancer: a multi-institutional phase II trial investigating three radiotherapy dose levels.

BACKGROUND: We hypothesized induction chemotherapy (IndCT) would improve distant control (DC) without compromising locoregional control (LRC) for locoregionally advanced head and neck cancer patients. Additionally, we systematically lowered radiotherapy (RT) doses attempting to maintain LRC while decreasing toxicity. PATIENTS AND METHODS: Stages III-IV (M0) locoregionally advanced head and neck cancer patients received carboplatin/paclitaxel (Taxol) IndCT followed by four or five cycles consisting of 5 days of paclitaxel, fluorouracil, hydroxyurea, and BID RT followed by a nine day break. RT dose to gross disease (high risk), intermediate, and low-risk volumes were reduced from cohort A (n = 68): 75, 60, and 45 Gy; to cohort B (n = 64): 75, 54, and 39 Gy; then cohort C (n = 90): 72, 51, and 36 Gy. RESULTS: A total of 222 patients accrued from November 1998 to September 2002. Median follow-up is 56 months. In all, 93/96/76% achieved a complete response to concurrent chemoradiotherapy (CRT) in cohort A/B/C. Three- and 5-year overall survivals (OSs) are 68% and 62%, respectively. Five-year LRC and DC are 91% and 87%, respectively. Response to IndCT predicted for OS, LRC, and time to progression (TTP). Cohort C patients had similar OS (P = 0.95), LRC, and DC, but worse (TTP) (P = 0.027). CONCLUSIONS: IndCT before CRT reduces distant progression while maintaining high LRC. The cohort B schedule provides the best therapeutic ratio. A randomized trial investigating IndCT before CRT has been initiated.