Their first report in 1990 shows that 16 family members were affected by severe abnormality, characterised by difficulty to speak effectively, understand complex sentences, unable to learn sign language, and that the condition was genetically inherited (autosomal dominant).
In their 1990 study, it was noted that 16 family members experienced severe abnormalities, including communication issues, difficulty understanding complex sentences, incapability to learn sign language, and these conditions were passed down genetically in an autosomal dominant manner.