Presentation
Rapid cognitive decline over 12 months. Unable to complete tasks of daily living (e.g. making coffee).
Patient Data
Advanced frontotemporal atrophy, predominantly involving the high frontal lobes (the superior and middle frontal gyri) with markedly thinned cortex with loss of normal grey white differentiation. The mesial temporal lobes are less severely involved but there is slight asymmetrical involvement of the left greater than right anterior temporal pole.
No gross abnormality of the brainstem, in particular no mid brain atrophy. No intra or extraaxial mass, hemorrhage or infarction. Perfusion study demonstrates decreased bifrontal CBV.
Conclusion:
Advanced frontotemporal atrophy, overall pattern favoring frontotemporal dementia.
TECHNICAL PROCEDURE AND RESULTS Technetium labeled Ceretec was injected and SPECT images of the brain obtained. The injection was during mental stimulation conditions. Significantly decreased perfusion to the posterior frontal lobes, the parietal lobes, as well as the temporal lobes (left > right, medial more than lateral) was seen.
OVERALL IMPRESSION The most striking features are reduced perfusion to the temporal lobes and the posterior posterior frontal lobes. Reduced perfusion to the parietal lobes is also seen.
The patient went on to have genetic testing.
Genetic testing
Progranulin gene mutation result: No mutations detected
Mutations in the Progranulin gene GRN on chromosome 17q21 (in close proximity to the MAPT gene) have been associated with autosomal dominant frontotemporal lobular degeneration with ubiquitin-immunoreactive neuronal inclusions (FTLD-U). In this analysis each exon of the GRN gene was amplified from genomic DNA by PCR and bi-directionally sequenced on an ABI 3130x1 Genetic Analyzer, and compared to the NG 007886.1 reference sequence using Mutation Surveyor Software.
TAU gene mutation Result: No mutations detected
A number of neuropathologies, particularly a familial subtype of fronto-temporal dementia have been linked to the gene encoding the microtubule-associated Tau protein (MAPT) on chromosome 17; mutations to MAPT are responsible for 10-20% familial frontotemporal dementia. In this analysis each exon of MAPT was amplified by PCR and bi-directionally sequenced on an ABI 3130x1 Genetic Analyzer, and compared to the NG_007398.1 reference sequence using Mutation Surveyor Software.
Several heterozygous polymorphisms were detected, including 5'UTR, IVS2, IVS3, IVS8, 1VS11 and exonic SNP's as listed below; several which are non-synonymous (change the amino acid). All but one however have been reported as non-pathogenic. One has not been previously reported and therefore its pathogenicity is unknown.
NOTE : In family DNA studies, the accuracy of diagnosis assumes stated relationships within a kindred, clinical diagnosis and identification of samples to be correct.
Case Discussion
On further investigation, the patient's mother had a frontotemporal dementia and died at an early age. Although a known mutation was not identified, a genetic basis is assumed. DNA from the mother is unavailable for comparison.
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