Patients with features similar to Huntington's disease, without CAG expansion in huntingtin.
OBJECTIVE
To describe characteristics of gene-negative patients with clinical features of Huntington's disease (HD), exploring likely etiologies.


BACKGROUND
When a direct gene test became definitive for diagnosis of HD, we discovered a number of patients in our clinics in Baltimore, MD, and Cambridge, UK, believed or suspected to have HD who did not have the triplet repeat expansion.


METHODS
Patients were examined using standardized instruments, and given full neurologic and psychiatric evaluations. Those negative for HD were tested for dentatorubro-pallidoluysian atrophy, SCA-1, SCA-3, SCA-2, SCA-6, and other conditions as indicated.


RESULTS
Of 15 patients, 7 received specific diagnoses or appear to be sporadic cases, 4 have a possible but uncertain relation to HD, and 4 have unknown familial progressive movement disorders.


CONCLUSIONS
This last group of patients might be properly described as phenocopies of HD, some of which may be caused by unidentified triplet repeat expansions.
Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
A
A
Rosenblatt
N G
NG
Ranen
D C
DC
Rubinsztein
O C
OC
Stine
R L
RL
Margolis
M V
MV
Wagster
M W
MW
Becher
A E
AE
Rosser
J
J
Leggo
J R
JR
Hodges
C K
CK
ffrench-Constant
M
M
Sherr
M L
ML
Franz
M H
MH
Abbott
C A
CA
Ross
D000328:Adult; D001923:Brain Chemistry; D015331:Cohort Studies; D005192:Family Health; D005260:Female; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000175:diagnosis / Q000235:genetics*; D008279:Magnetic Resonance Imaging; D008297:Male; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype; D018911:Trinucleotide Repeats
C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins