CHRNA7 and schizophrenia: Deletions involving CHRNA7 are rare but are strongly associated with schizophrenia [72,73]: these patients only have one copy of CHRNA7 and two copies of CHRFAM7A, leading to an altered CHRNA7/CHRFAM7A ratio, whereas 15q13.3 duplication has been linked to childhood-onset schizophrenia [110].