New genetic test allows faster diagnosis of congenital cataract

A new blood test for children born with cataracts can search for all genes known to cause congenital cataract using just one blood sample.

“Using next-generation sequencing, we are now able to identify the cause of cataracts in children in a way that is much faster and more cost-effective than the current method," said Rachel Gillespie of the Centre for Genomic Medicine at The University of Manchester in the UK, who was part of the team that developed the test.

Conventional screening methods, on the other hand, involve the consecutive testing of each gene separately to determine the precise genetic cause, which is time-consuming and costly. Around half of the cases of congenital cataract are due to genetic mutations.

“At the moment, screening for one gene takes around four weeks,” said Gillespie. “There are more than 100 known genes linked to congenital cataracts, so establishing the cause by screening genes individually can sometimes take years. Our test looks at all of these genes in parallel so patients can be diagnosed much faster and receive the treatment, clinical management and genetic counseling they need.”

The research team said that as more patients are tested and more knowledge is gained about the genetic basis of congenital cataracts, it is hoped that pinpointing the exact mutation responsible will enable doctors to make more accurate predictions regarding how cataracts may progress and what the outcome of surgery may be. Genetic testing can also reveal more complex conditions whose symptoms typically do not emerge until later in life.

“In some cases, we have identified that the cataracts aren't just a standalone problem, but a symptom of a more complex syndrome,” said Gillespie. “This includes Warburg micro syndrome and galactokinase deficiency, both rare conditions that are probably underdiagnosed, as warning signs in children can be subtle.”

The researchers currently are validating the test. It is expected to become available through the National Health Service in the UK in December, at which time samples will be accepted for diagnostic testing.