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To the Editor: Genetic inheritance of Tourette’s syndrome was observed as early as the 19th century (1). To date, no clear susceptibility genes for Tourette’s syndrome have been identified. However, a recent linkage study that utilized a whole-genome screen found evidence of linkage of Tourette’s syndrome to a region on chromosome 2p (2). The identification of chromosomal structural aberrations that coincide with a particular phenotype could provide insight into the genesis of this disease. We report the case of a father and son who were clinically diagnosed with Tourette’s syndrome and had a shared chromosomal alteration.
“Mr. A” was a 47-year-old married man who suffered from motor tics, such as head jerking, teeth grinding, and touching walls. Additionally, he experienced symptoms of coprolalia. Apart from the tics, no abnormality was detected in his clinical examination. His family history was positive, with a 9-year-old son who also suffered from complex motor and single vocal tics as well as a learning disability. Both father and son were diagnosed with Tourette’s syndrome in accordance with DSM-IV criteria (3). Mr. A’s 12-year-old daughter did not show any symptoms of the disease. Peripheral blood samples were obtained from Mr. A and both children and their mother, with informed consent from the parents and the children. G-banding by Trypsin-Giemsa analysis and karyotyping of metaphase chromosomes were undertaken via peripheral blood lymphocytes in accordance with standard cytogenetic protocols. Both the affected father and the affected son exhibited the same balanced translocation t(6;17)(q21;p11). The mother and daughter showed a normal karyotype. Since the children’s grandparents were deceased, cytogenetic examination of the grandparents, who had been healthy and not consanguineous, was not possible. Thus, a de novo translocation could not be excluded.
In our case, a father-to-son transmission of a balanced translocation involving chromosomes 6q21 and 17p11, segregating with Tourette’s syndrome, was observed. Chromosome 17p11 was identified for suggestive linkage in a linkage analysis of affected sibling pairs with attention deficit hyperactivity disorder—also a Tourette’s syndrome spectrum disorder (4)—as well as for linkage in schizophrenia patients (5). The biological and physiological parallels of Tourette’s syndrome and schizophrenia have been described previously (6).
The translocation found could have emerged in a former generation, and a coincidentally occurring segregation is still a possibility. Even if this is the case, isolation of the genomic region at the site of the translocation breakpoints on chromosomes 6 and 17 might be useful in the search for candidate Tourette’s syndrome genes.
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