Lack of variation in the nucleotide sequence corresponding to the transmembrane domain of the beta-amyloid precursor protein in Alzheimer's disease.

The nucleotide sequence corresponding to the APP transmembrane domain and flanking regions of charged amino acids was determined for 91 patients with histologically confirmed Alzheimer's disease, 9 patients with dementias of other etiologies, and 14 controls who had no identifiable brain disease. Twenty-eight of the AD patients had a first-degree relative with dementia. No mutations were detected among the 100 demented patients. However, one of the 14 controls exhibited a change in the 3' base of codon 716 which would not be expected to result in an amino acid substitution at this position.