Gene sequencing changes treatment for metabolic conditions

Genetic testing can improve the treatment of developmental delay in children when it's caused by an underlying metabolic disorder.

The small study found that genetic testing was able to pick up on these metabolic disorders, which are often treatable, after blood and urine analysis had come back negative.

Lead author Dr Clara van Karnebeek, biochemical geneticist and paediatrician at British Columbia Children's Hospital in Canada, said: 'This research is very encouraging because for a subset of patients we can identify the genetic underpinning of their intellectual disability and then determine the right intervention.'

Some metabolic disorders can cause a build-up of toxins in the body, which in turn causes cognitive and developmental delays, ranging from delayed walking to epilepsy and autism. After a traditional urine and blood screen came back negative for known metabolic diseases linked to developmental delay in 41 children, Dr. van Karnebeek’s team sequenced the genes of each patient. 

They uncovered underlying metabolic causes of developmental delay in 28 out of the 41 children. The researchers were then able to prescribe new, targeted treatments to 17 of these children. The research team also discovered 11 genes that had not previously been linked to developmental delay. This may offer a new line of enquiry for many diseases with unknown causes although Dr van Karnebeek cautions that genetic screening is 'expensive at this time, costing a couple of thousand dollars, on average.'

Unexplained intellectual development disorder may affect up to three percent of the global population. If an underlying metabolic problem is the cause, treatment is much more straightforward. By knowing the missing nutrient, doctors can often prescribe a simple diet change or vitamin supplement to treat the symptoms.

Dr Edward McCabe, chief medical officer for the March of Dimes, told UPI: 'As sequencing gets cheaper, it's the way we need to go to identify the cause of disorders in these patients.'

The research was published in the New England Journal of Medicine.