Mutations in 3 genes involved in the breakdown and recycling of cellular components in the brain may cause about 10% of stuttering cases, according to a study led by researchers from the National Institute on Deafness and Other Communication Disorders.
The scientists found that a mutation in the gene encoding N-acetylglucosamine-1-phosphate transferase (GNPTAB) was associated with stuttering in a large, closely related Pakistani family, and this mutation was found in only 1 of 192 unrelated, unaffected Pakistani individuals and in none of 552 unaffected North American individuals (Kang C et al. N Engl J Med. 2010;362:677-685). They also identified 3 mutations in a gene that encodes the γ subunit of N-acetylglucosamine-1-phosphate transferase (GNPT) in Asian and European individuals who stutter but not in controls. Finally, they found 3 mutations in the N-acetylglucosamine-1-phosphodiester α-N acetylglucosaminidase gene (NAGPA), which is involved in the same pathway, in individuals who stutter but not in controls.
Kuehn BM. Stuttering Genes. JAMA. 2010;303(12):1139. doi:10.1001/jama.2010.299