[Clinical characteristics of a family with early-onset Alzheimer's disease associated with a presenilin 1 mutation (M139T)].
BACKGROUND
The objective of this study was to describe the clinical features and the genetic analysis of a family with autosomal-dominant familial Alzheimer's disease.


METHODS
In addition to the clinical findings of different family members, we performed a genetic analysis to detect mutations in the amyloid precursor protein genes, presenilin 1 and presenilin 2 genes, by means of single-strand conformation polymorphism and subsequent sequencing. The APOE genotype was also determined.


RESULTS
The proband was a 52-year-old patient whose Alzheimer's disease started at age 49 years. Family history revealed that several members had developed an early onset dementia. The clinical picture in all them was characterized by cognitive and behavioral abnormalities that started at age 40 to 50 years. An important variability in the age of onset was observed among family members (range 39-51 years). The proband's genetic study identified a mutation in the presenilin 1 gene which predicted a methionine-to-treonine substitution at codon 139 (M139T). APOE genotype was *3/*3.


CONCLUSIONS
The clinical picture of this family carrying the M139T mutation was similar to that of the sporadic variant of Alzheimer's disease. The observed variability in the age of onset suggests that, yet being genetically determined, other genetic or environmental factors modify the clinical expression of the disease.
Lleó
Alberto
A
Neurología, Hospital Clínic, Barcelona, Spain.
Blesa
Rafael
R
Gendre
Jordi
J
Castellví
Magda
M
Molinuevo
José Luis
JL
Oliva
Rafael
R
D000328:Adult; D000367:Age Factors; D000544:Alzheimer Disease / Q000175:diagnosis / Q000235:genetics* / Q000401:mortality; D005260:Female; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008875:Middle Aged; D009154:Mutation; D010375:Pedigree; D053764:Presenilin-1; D013997:Time Factors
D008565:Membrane Proteins; C508853:PSEN1 protein, human; D053764:Presenilin-1