A Frameshift Variant in the CHST9 Gene Identified by Family-Based Whole Genome Sequencing Is Associated with Schizophrenia in Chinese Population

Recent studies imply that rare variants contribute to the risk of schizophrenia, however, the exact variants or genes responsible for this condition are largely unknown. In this study, we conducted whole genome sequencing (WGS) of 20 Chinese families. Each family consisted of at least two affected siblings diagnosed with schizophrenia and at least one unaffected sibling. We examined functional variants that were found in affected sibling(s) but not in unaffected sibling(s) within a family. Matching this criterion, a frameshift heterozygous deletion of CA (–/CA) at chromosome 18:24722722, also referred to as rs752084147, in the Carbohydrate Sulfotransferase 9 (CHST9) gene, was detected in two families. This deletion was confirmed by PCR-based Sanger sequencing. With the observed frequency of 0.00076 in Han Chinese population, we performed both case-control and family-based analyses to evaluate its association with schizophrenia. In the case-control analyses, Chi-square test P-value was 6.80e-12 and the P-value was 0.0008 after one million simulations. In family-based segregation analyses, segregation P-value was 7.72e-7 and simulated P-value was 5.70e-6. For both the case-control and family-based analyses, the CA deletion was significantly associated with schizophrenia in the Chinese population. Further investigation of this gene is warranted in the development of schizophrenia by utilizing larger and more ethnically diverse samples

Identification of CHST9 as A Candidate Gene for Schizophrenia from Whole Genome Sequencing

Recent results imply that rare variants contribute to the risk of schizophrenia. We conducted whole genome sequencing for 99 subjects from 20 Chinese families (parents and at least two siblings with a schizophrenia diagnosis and one unaffected sibling). Of the 9 frameshift mutations identified in more than 2 families, one was at chromosome 10:125780762 on the Carbohydrate Sulfotransferase 15 (CHST15) gene and another at chromosome 18:24722723 on the Carbohydrate Sulfotransferase 9 (CHST9) gene. We observed these deletions in 4 affected persons of two families from whole. At least two types of mutations (one or three bases insertion) have been identified in 6 families. Given the frequencies of these mutations observed in the general population (data from ExAC database:http://exac.broadinstitute.org/) are between 0.002 to 0.00001, the largest p-value that CHST15 is associated with schizophrenia is less than 0.002^6, or 6.4E-17. This finding was replicated in an independent Chinese sample of 85 subjects from 17 families, where 7 families were found with similar mutations at the same location. We are in the process to validate these mutations by PCR- and cloning-based Sanger Sequencing. CHST15 and CHST9 has been reported to be associated with cancers but never with schizophrenia. Further study of the biological functions of CHST15 and CHST9 genes are warranted to understand their contribution to schizophrenia

A Frameshift Variant in the CHST9 Gene Identified by Family-Based Whole Genome Sequencing Is Associated with Schizophrenia in Chinese Population.

Recent studies imply that rare variants contribute to the risk of schizophrenia, however, the exact variants or genes responsible for this condition are largely unknown. In this study, we conducted whole genome sequencing (WGS) of 20 Chinese families. Each family consisted of at least two affected siblings diagnosed with schizophrenia and at least one unaffected sibling. We examined functional variants that were found in affected sibling(s) but not in unaffected sibling(s) within a family. Matching this criterion, a frameshift heterozygous deletion of CA (-/CA) at chromosome 18:24722722, also referred to as rs752084147, in the Carbohydrate Sulfotransferase 9 (CHST9) gene, was detected in two families. This deletion was confirmed by PCR-based Sanger sequencing. With the observed frequency of 0.00076 in Han Chinese population, we performed both case-control and family-based analyses to evaluate its association with schizophrenia. In the case-control analyses, Chi-square test P-value was 6.80e-12 and the P-value was 0.0008 after one million simulations. In family-based segregation analyses, segregation P-value was 7.72e-7 and simulated P-value was 5.70e-6. For both the case-control and family-based analyses, the CA deletion was significantly associated with schizophrenia in the Chinese population. Further investigation of this gene  is warranted in the development of schizophrenia by utilizing larger and more ethnically diverse samples