Locations of CHRNA4 rare variants identified in the discovery and the test samples.(A) Schematic genomic structure of CHRNA4 spanning 17 Kb and 6 coding exons (dark boxes). Red arrows point to the identified rare nonsynonymous variants in the discovery samples; green arrows point to the identified rare synonymous variants in the discovery samples. The bars on the top show the PCR products. The dark grey region covering exon 5 was sequenced in the test samples.(B) Schematic depiction of the α4 nAChR subunit. Exon 5 was sequenced in the test samples, which encodes 114 amino acids of the extracellular domain, all of the first three transmembrane domains, and 256 amino acids of the cytoplasmic loop. Amino acids encoded by the gene regions not sequenced in the test stage are depicted in light grey. Red dots represent the amino acids affected by rare nonsynonymous variants identified in the test samples; green dots are those affected by rare synonymous variants identified in the test samples.
