Exclusion of Five Trinucleotide Repeat (CAG and CCG) Expansions in 17 Families with Schizophrenia

Trinucleotide repeat expansion diseases are characterized by anticipation. Several studies suggested the anticipation in schizophrenia. We studied five novel trinucleotide repeats identified by Li et al in a human brain cDNA library in 100 unrelated control subjects, and 57 subjects in 17 families with schizophrenia. The CTG- B43 and B45d, and CCG-A3 were not polymorphic in any unrelated control subjects or subjects with familial schizophrenia. The CTG-A4 had two alleles and the CTG-B1 three alleles. The two clones were not expanded in subjects with familial schizophrenia or unrelated healthy controls. There was no difference in allele frequency between unrelated control subjects and subjects in the families with schizophrenia. The allele frequencies in unaffected and affected subjects in the families with schizophrenia were not significantly different. There was no difference between the offspring and parental generations of affected subjects in the families with schizophrenia. The results suggest the exclusion of the five trinucleotide repeat expansions in the 17 families with schizophrenia.