A case of dementia with PRNP D178Ncis-129M and no insomnia.

OBJECTIVE

To describe a dementia case clinically diagnosed as Alzheimer disease with a PRNP genotype usually associated with familial fatal insomnia.

METHODS

Polymerase chain reaction amplification and subsequent direct sequencing of PGRN, MAPT, PSEN1, PSEN2, APP, and PRNP genes.

RESULTS

A point mutation (D178N) was found in the PRNP gene.

CONCLUSIONS

The mutation D178N in the PRNP gene associated with the M129 genotype is usually associated with familial fatal insomnia. However, a few cases have been reported with different clinical phenotypes. Here, we describe one of these cases and stress the importance of genetic screening of PRNP in early onset dementia cases.