Five probands were initially identified. All of them have neurodevelopmental disabilities with deficits especially noted in speech, including two probands who are non-verbal at 7 years of age. Seizures were reported in five individuals, with onset ranging from 2 months to 13 years of age. Three of the five individuals have abnormal brain MRIs, but the abnormalities are not consistent. Among them, one proband with homozygous TIAM1 p.Gly328Val variant exhibited progressive macrocephaly thought to be secondary to chronic subdural hematoma or extra-axial fluid and diffuse cerebral atrophy, but it is unclear if these MRI features are primary to the condition or potentially due to another cause. Other medical features observed in one or two probands include autism, hypothyroidism, Addison’s disease, congenital heart disease with septal defects, hypomagnesemia, and difficulty in gaining weight.
TIAM1