New genetic analysis tools improve diagnosis of intellectual disability

Published: 2019-11-13


Enabled by the SciLifeLab Clinical Genomics facility, researchers have developed new whole-genome sequencing analytical tools capable of diagnosing intellectual disabilities more accurately than previous methods. The new tools will now be introduced for first-line clinical diagnosis at the Karolinska University Laboratory.

“Recent technical leaps in genetic diagnostics have revealed many new genetic aberrations that cause intellectual disability. Given that there are currently over 800 different diagnoses described in the literature, making a diagnosis can be a time-consuming process,” says Anna Lindstrand (Karolinska Institutet), first author of the study.

Approximately 1.5 percent of the Swedish population are carrying some kind of genetic aberration ranging from single point mutations to larger structural chromosome mutations leading to intellectual disability of varying severity.

Individuals with intellectual disabilities are commonly offered genetic clinical examination to rule out large scale chromosomal aberrations as well as Fragile X syndrome – one specific inherited genetic condition that can cause a range of developmental problems including learning disabilities and cognitive impairment. About 12 percent of these analyses produce a molecular causal diagnosis. In cases where no molecular diagnosis could be found, further testing with additional techniques can be offered.

In the study, published in Genome Medicine, senior author Daniel Nilsson (SciLifeLab/Karolinska Institutet), and the other researchers developed new whole-genome sequencing analytical tools that were more efficient in discovering point mutations, structural chromosome aberrations and repetitions (expansions). In fact, twice as many patients (27 percent) could obtain a causal diagnosis.

“In just a short space of time, whole-genome sequencing has become inexpensive enough to be used as an all-round test for finding different genetic mutations,” says Dr Lindstrand. “The cost of sequencing a person’s entire genome is now just marginally higher than other genetic analyses currently employed to find genetic mutations.”

Karolinska University Laboratory in Stockholm, Sweden, will now be one of the first clinical laboratories in the world to introduce whole-genome sequencing as a first-line clinical diagnostic tool for intellectual disability.

“This is made possible by cutting edge expertise from several fields being brought together,” says Dr Nilsson. “We now have the collaborative strength to make tools that can solve the genetic riddles and bring answers to the affected individuals.”

Read the entire press release here.