Conceptual art of a DNA strand

Schizophrenia is known to run in families, and appears to have a genetic cause. But those genes are so complex and numerous, it’s been a biological puzzle that scientists have yet to piece together.

A handful of DNA errors like deletions or duplications were found within 41,000 full genomes analyzed of schizophrenic and control patients, according to a new study helmed by researchers at the University of California San Diego School of Medicine, published this week in the journal Nature Genetics.

“This study represents a milestone that demonstrates what large collaborations in psychiatric genetics can accomplish,” said Jonathan Sebat, the lead author.

More than 260 researchers involved in the Psychiatric Genomes Consortium took part in the work, which assessed the entire genetic makeup of 21,000 people with schizophrenia and 20,000 without the condition.

The copy-number variants, the errata in the genes, were found at eight specific locations in the genomes. Those locations were most often integral to synapse function, they found.

But those variants at the eight locations were involved in only 1.4 percent of the schizophrenia cases. Much more work remains to parse through other variants that play a part in the condition, the team said.

“We’re confident that applying this same approach to a lot of new data will help us discover additional genomic variations and identify specific genes that play a role in schizophrenia and other psychiatric conditions,” said Sebat.

Genes are only part of the puzzle, as well. The National Institutes of Health said the work so far indicates that DNA is not destiny – and that environmental factors play a part in determining whether the target genes are activated during life, and create the conditions for the disorder.

“Many environmental factors may be involved, such as exposure to viruses or malnutrition before birth, problems during birth, and other, not yet known, psychosocial factors,” they write.