Small eye (Sey) in mouse is a semidominant mutation which in the homozygous condition results in the complete lack of eyes and nasal primordia. On the basis of comparative mapping studies and on phenotypic similarities, Sey has been suggested to be homologous to congenital aniridia (lack of iris) in human. A candidate gene for the aniridia (AN) locus at 11p13 has been isolated by positional cloning and its sequence and that of the mouse homologue has been established (C.T., manuscript in preparation). This gene belongs to the paired-like class of developmental genes first described in Drosophila which contain two highly conserved motifs, the paired box and the homeobox. In vertebrates, genes which encode the single paired domain as well as those which express both motifs have been described as the Pax multigene family. A Pax gene recently described as Pax-6 is identical to the mouse homologue of the candidate aniridia gene. Here we report the analysis of three independent Sey alleles and show that indeed this gene is mutated and that the mutations would predictably interrupt gene function.

Based on the map location of the aniridia (AN) locus in human chromosomal band 11p13, we have cloned a candidate AN cDNA (D11S812E) that is completely or partially deleted in two patients with AN. The less than 70 kb smallest region of overlap between the two deletions encompasses the 3' coding region of the cDNA. This cDNA, which spans over 50 kb of genomic DNA, detects a 2.7 kb message specifically within all tissues affected in AN. The predicted polypeptide product possesses a paired domain, a homeodomain, and a serine/threonine-rich carboxy-terminal domain, structural motifs characteristic of certain transcription factors. The concordance between expression and pathology, map location, structure, and predicted function argues that the cDNA corresponds to the AN gene.

No abstract

The A1 allele of the dopamine D2 receptor gene (DRD2) is associated with a reduced number of dopamine binding sites in the brain and with the increased likelihood of substance abuse and addictive behavior. In a study of smokers enrolled in an open-label, randomized effectiveness trial, we investigated whether variants in the DRD2 receptor gene are associated with smoking cessation outcomes following treatment with a combination of bupropion SR and behavioral counseling. Adherence to treatment and pointprevalent smoking status were assessed at 3 and 12 months, respectively, following a target quit date. Compared to women who carry both A2 alleles, women with at least one A1 allele were more likely to report having stopped taking bupropion due to medication side effects (odds ratio (OR) ¼ 1.91, 95% confidence interval (CI) ¼ 1.01-3.60; Po0.04) and at 12 months were somewhat more likely to report smoking (OR ¼ 0.76, 95% CI ¼ 0.56-1.03; Po0.076). Significant associations or trends were not observed in men. In women, individual variability in responsiveness to bupropion-based treatment may be partially due to differences in genetic variants influencing dopamine receptor function. INTRODUCTIONTobacco use remains the major preventable cause of premature disability and death in developed countries. Despite best efforts to date, 46 million people still smoke in the United States, and over 440 000 people die each year from tobaccorelated illness; the estimated smoking-related cost to the economy is $157 billion annually.1 Effective pharmacologic interventions for smoking cessation include several forms of nicotine replacement and the use of the antidepressant medication, bupropion.2 Despite treatment advances, smoking relapse after successful intervention for smoking cessation occurs in 70 to 80% of patients within 12 months. [3][4][5] Still to be determined is why some people remain nonsmokers after pharmacologic intervention and others do not.The dopaminergic mesocorticolimbic pathway in the brain is thought to play an important role in tobacco and nicotine addiction. [6][7][8] The TaqIA polymorphism of the dopamine D2 receptor gene (DRD2) results from a C/T

Although these results are suggestive, a more compelling test is needed of the hypothesis that dopaminergic gene interaction underlies, in part, the likelihood of smoking following treatment with bupropion SR. Most likely this will come from larger studies involving prospective randomization to treatment based on genotype.