Recent studies have shown an association between trinucleotide repeat expansions (TREs) and adult-onset schizophrenia (AOS). Childhood-onset schizophrenia (COS) is a severe variant of schizophrenia with onset of symptoms before age 12 years. We have used the repeat expansion detection (RED) method to investigate the occurrence of repeat expansions in a group of well-characterized COS patients as well as a set of clinically related childhood-onset psychosis cases labeled 'multidimensionally impaired' (MDI). The difference observed in the CAG/CTG RED product distribution between normal (n = 44) and COS (n = 36) samples was only marginally significant (P = 0.036). However, male COS samples (n = 20) had a significantly different RED product distribution compared to male controls (n = 25, P = 0.002) with longer RED products in COS. No such difference was seen in females (n(cont) = 19; n(cos) = 16; P = 0.236). The difference remained significant between male COS (n = 12) and male controls (n = 24) when only Caucasian samples were used (P = 0.003). Similarly, the RED product distribution in male MDI samples (n = 18) was significantly different compared to male controls (P = 0.018). Some of the detected TREs in all three populations (COS, MDI and control) correlated with expanded alleles found at the CTG18.1 locus on chromosome 18. In conclusion, we have found an association between TREs and COS. This association is specifically significant in the male population. Thus, the occurrence of an expanded trinucleotide repeat may contribute to the genetic risk of COS, possibly in combination with other factors.
Bibliographical noteFunding Information:
We are indebted to the families for their invaluable participation. This study was funded by the EC Biomed 2 (grant BMH4-97-2466), Swedish Medical Research Council (K97-13X-10909-04AK), Svenska Läkarsällska-pet, Thuring stiftelse, Söderström-Königska stiftelse, funds from the Karolinska Institute and Karolinska Hospital. CEB is the recipient of an award from the Scottish Rite Benevolent Foundation’s Schizophrenia Research Program, NMJ, USA. KL is the recipient of the Swedish MRC Methodology scholarship. MS is the recipient of the Ireland Award, a NARSAD Established Investigator Award.
- Multi-dimensionally impaired
- Neuropsychiatric disorders
- Repeat expansion detection
- Trinucleotide repeat expansion