Psychiatric disorders show sex differences and early-onset neurodevelopmental disorders, such as ADHD, conduct disorder and autism are more common in males (Ober et al, 2008). In other disorders, such as schizophrenia, there is an earlier age of onset and worse prognosis for men (Ober et al, 2008). The Y chromosome is potentially an important influence on male susceptibility to neuropsychiatric disorders. Animal models have indicated a role for Y chromosome in aggression and impaired parental behaviour (Gatewood et al, 2006). However, due to difficulties arising from the lack of recombination, the Y chromosome has been largely excluded from genetic studies of neuropsychiatric disorders. Although the Y chromosome has been investigated in relation to autistic traits (Jamain et al, 2002) and aggression (Shah et al, 2009) in humans, these studies have not used Y chromosome haplogroups appropriately. Even though Y chromosome markers are now present on most genome-wide association chips, Y chromosome haplogroup analysis is not routinely included in genome-wide association reports of sexually dimorphic disorders.

For my PhD research I had derived Y chromosome haplogroups in children with ADHD from Cardiff University and controls. Although, there were no haplogroups overepresented in children with ADHD, there was a difference in IQ scores across haplogroups only within cases with ADHD. However, this study was based on small number of individuals and since then more Y chromosome markers for deriving haplogroups have become available.

Y chromosome haplogroups have been derived for all male participants with GWAS data in ALSPAC.

We are planning to test if Y chromosome haplogroups, that have already been derived in children from the ALSPAC study, are associated with number of ADHD symptoms, number of autistic symptoms, number of conduct disorder symptoms and number of psychotic symptoms.

We are also planning to test if this association is mediated though IQ or educational attainment.

ANOVA will be used to perform association testing between Y chromosome haplogroups and number of psychiatric disorder symptoms. ANOVA will be also used to test if Y chromosome haplogroups are associated with IQ or educational attainment as measured by GCSE and A levels results. Social class will be included as a covariate in analyses.