Case 358 -- A male in his 40s with severely compromised vision

Contributed by Laurentia Nodit, MD, Melina Flanagan, MD, MSPH and Jeffrey Kant, MD, PhD
Published on line in August 2003

PATIENT HISTORY:

A male in his 40s with a prior medical history of Behcet's disease and severely compromised vision presented with a cognitive disorder and chorea. His symptoms began 8 years ago, over which time the patient has steadily deteriorated. His mother had similar symptoms and was diagnosed as having Huntington disease. Few family members on the maternal side were also affected (see Pedigree). None of the mother's relatives were previously tested.

Peripheral blood was submitted for genetic testing of Huntington disease.

RESULTS:

Image 1. Fragment size analysis on ABI 377 sequencer using Genescan software.
Rows represent relative molecular weights of PCR-amplified products. Red bands are internal size standards.
Columns represent patient samples or controls:

1-2: Patient run in duplicate using 'short' primers
3: Control, 17/23 repeats
4: Control, 16/33 repeats
5: Control, 13/42 repeats
6: Control, 14/68 repeats
7: Blank - no sample
8-9: Patient run in duplicate using 'long' primers.

Image 2: Genescan analysis for patient alleles in duplicate reactions using 'short' primers. For unknown reasons, amplification was weak for the larger allele under these conditions.

Image 3: Genescan analysis for patient alleles in duplicate reactions using 'long' primers

Results:   Allele 1, 18 CAG repeats (normal range)   Allele 2, 39 CAG repeats (borderline range)

FINAL DIAGNOSIS