Practitioners at the Clinic for Special Children in Pennsylvania are using GeneChip microarrays developed by Affymetrix to discover the genetic cause of diseases at an unprecedented pace. The researchers have uncovered the cause of more than half a dozen diseases in the past 12 months, the most recent discovery being a mutated gene causing a mysterious developmental disorder in the Mennonite population.
The aim of the non-profit Clinic is to find treatments for a variety of rare genetic diseases that have long afflicted children in Plain sect communities, such as the Amish. While the diseases under observation are far more common in the Plain sects, such findings have worldwide ramifications, providing the basis for genetic tests of rare diseases in the general population.
An example of the technology at work can be provided through the team’s most recent discovery that a girl suffering from slow growth and developmental delay was actually experiencing symptoms of Salla disease.
While recent estimates place about 25,000 genes in the human genome, the team narrowed their search to just 55 genes on chromosome 6 by using GeneChip Mapping 10K microarrays to scan 10,000 genetic variations from the child and her family. They discovered a mutated version of the SLC17A5 gene to be responsible; a mutation identical to that which causes Salla disease in the Finnish population. This allowed the physicians to diagnose Salla disease in four additional individuals by testing for the SLC17A5 mutation directly.
“Our most recent study using GeneChip arrays took less than one month to complete and cost less than $4,000 dollars to make a definitive diagnosis of Salla disease,” said Kevin Strauss a pediatrician at the clinic. “That same patient had undergone four years of standard medical exams, totaling nearly $20,000 dollars, but the diagnosis was elusive until we looked at her genome with the 10K microarray.”