Until the mid-2000s, when effective techniques for detecting CNVs were developed, scientists thought that CNVs caused only a small number of health disorders. Today, tens of thousands of different CNVs have been discovered and linked to several disorders—including autism, schizophrenia, and Parkinson's disease.
To see if CNVs are involved in congenital kidney defects, Drs. Gharavi and Sanna-Cherchi scanned the genomes of 522 individuals with small and malformed kidneys from medical centers in Europe and United States. About 17 percent of the patients carried a CNV that appeared to contribute to their kidney disorder.
In studies of children with previously discovered CNVs, most of the CNVs had been linked to developmental delays or mental illness. In the current study, about 1 in 10 children had a CNV linked to developmental delays or mental illness.
Though it remains unclear why kidney malformations and neurodevelopment are linked in some cases, it is possible that the same genes involved in kidney development are involved in brain development, Dr. Gharavi said.
Congenital kidney disease may involve hundreds of genes
The search for CNVs in congenital kidney disease also showed that the genes involved in the disease are far more numerous than anticipated.
"We thought we were going to find a few CNVs shared by many patients, but instead we found that virtually every patient with a CNV has a unique one," Dr. Gharavi said. "Virtually every patient has a unique condition that could not be diagnosed by a standard clinical evaluation."
Based on their results, Drs. Gharavi and Sanna-Cherchi estimate that there may be hundreds of different genes that can lead to congenital kidney malformation.
Source: Columbia University Medical Center