[Genetic markers in four Chilean families with familial Creutzfeldt-Jakob disease].
BACKGROUND
Creutzfeldt-Jakob disease (CJD) is a form of transmissible spongiform encephalopathy, in which a prion protein (PrP Sc) accumulates in the brain of affected individuals. Chile has a prevalence of CJD that is more than twice than in the rest of the world and has the highest rate of familial forms. These later forms are associated with the heterozygocity of codon 200 of PrP protein gene.


OBJECTIVE
To search susceptibility genetic markers of CJD in members of families affected by CJD.


METHODS
A blood sample was obtained from 50 individuals pertaining to four families affected by CJD. DNA from peripheral mononuclear cells was amplified by polymerase chain reaction and sequenced for the gene that codifies PrP protein.


RESULTS
In family A, 21 of 23 members were homozygotes for codon 129 (Met/Met) and eight were simultaneously heterozygotes for codon 200 (Glu/Lys). In family B, six of nine members were homozygotes for codon 129, five were heterozygotes for codon 200 and four had both mutations. In family C, the four analyzed subjects were homozygotes for codon 129 and two were simultaneously heterozygotes for codon 200. In family D, nine of 14 members were homozygotes for codon 129 and two were simultaneously homozygotes for codon 200. No family had polymorphisms for codon 219.


CONCLUSIONS
Thirty two percent of analyzed subjects were homozygotes for codon 129 and heterozygotes for codon 200, condition that defines the genetic susceptibility to acquire CJD. The dominant tendency of these genotypes could explain the higher incidence of CJF in Chile.
Cartier R
Luis
L
Departamento de Ciencias Neurológicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile. lcartoer@med.uchile.cl
Fernández O
Jorge
J
Ramírez V
Eugenio
E
D000595:Amino Acid Sequence; D001483:Base Sequence; D002677:Chile; D003062:Codon / Q000235:genetics*; D007562:Creutzfeldt-Jakob Syndrome / Q000235:genetics*; D005260:Female; D005819:Genetic Markers; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008297:Male; D009154:Mutation / Q000235:genetics*; D010375:Pedigree; D016133:Polymerase Chain Reaction; D018621:PrPC Proteins / Q000235:genetics; D018620:PrPSc Proteins / Q000235:genetics; D011328:Prions / Q000235:genetics*
D003062:Codon; D005819:Genetic Markers; D018621:PrPC Proteins; D018620:PrPSc Proteins; D011328:Prions