Genetic basis of stuttering discovered

In the largest study of its kind, a clear genetic basis has been found for the speech condition of stuttering.

In a genome-wide association study (GWAS), researchers at Vanderbilt University in Nashville, Tennessee, identified 57 unique areas in the human genome that are associated with stuttering, and 48 genes within these areas are related to the risk of stuttering. The results suggest stuttering shares molecular pathways with autism, depression, and musicality.

'No one really understands why someone stutters; it has been a complete mystery. And that's true for most speech and language pathologies. They are profoundly understudied because they don't put people in the hospital, but they can have enormous consequences on people's quality of life,' said Professor Jennifer Below, corresponding author of the paper published in Nature Genetics.

Stuttering is highly heritable and usually develops between two and five years of age, affecting both genders equally. Around 80 percent of affected children spontaneously recover; however, this is more common in girls, so that by adolescence and adulthood, men and boys are around four times more likely to be affected than their female peers.

Professor Below and co-author Dr Shelly Jo Kraft initially investigated the genetic causes of stuttering decades ago by collecting saliva and blood samples from around the world. Now, using data from 23andMe, they were able to perform a more comprehensive GWAS study on eight sex- and ancestry-specific groups, comprising nearly 100,000 affected people and over one million unaffected controls. A meta-analysis was used to combine the findings.

The genetic signature associated with stuttering was different between male and female participants, which the authors suggest could reflect the difference between ongoing and past stuttering.

The team also constructed polygenic risk scores from the male and female genetic signatures and tested them in data from two separate cohorts. They found that the polygenic score derived from the male signature – but not the one from females – could predict stuttering for both males and females.

The single gene with the strongest association with stuttering is VRK2, which has previously been linked to the self-reported ability to clap along with a beat, suggesting shared genetic architecture between language, speech and musicality.

'To begin to understand at a biochemical, molecular, cellular level what makes us who we are as a species – our capacity for communication – is incredibly cool, and we hope this will spur additional studies of this gene and its function in the brain,' said Professor Below.

Co-author Dr Dillon Pruett added: 'I stutter and this work has been really impactful for me... we hope to use this knowledge to dispel stigma related to stuttering and to develop new therapeutic approaches in future.'

The meaning, merit and uses of polygenic scores will be discussed at this year's PET Annual Conference, What Does Genomics Mean for Fertility Treatment?.

The conference is taking place in person in London on Wednesday 10 December 2025, with sessions including 'Polygenic Risk, Polygenic Scores, Polygenic Indices: What Are They? What Should Be Done With Them?'. Find out more and register her