[Clinical, neuroimaging and genetic features of two Chinese families with fatal familial insomnia]

Objective: To examine clinical, neuroimaging and genetic features of two Chinese families with fatal familial insomnia (FFI). Methods: The clinical data, including case history, physical examination, biochemical analysis of blood and neuroimaging of two pedigrees with FFI who admitted to the Navy General Hospital in 2014 and 2017 were collected. The D178N prion protein (PRNP) mutation were determined by DNA sequencing among the proband and family members. Results: There were 6 patients in 2 families, 5 male and 1 female. The onset age of disease in family 1 was 47 and 60 years old respectively, and 46, 58, 58, 60 years old respectively in family 2. In terms of disease course, patients in family 1 had a rapid disease course and died half year after onset while patients in family 2 had a relatively slow disease course and survived more than 1 year after onset.The induced factors of the patients in the family 1 were fright, followed by abnormal behaviors and sleep disorders accompanied by autonomic nervous dysfunction; the clinical features of the pedigree 2 were memory loss, decreased sleep and motor disorder without obvious inducement, and the autonomic nervous dysfunction was not significant. The neuroimaging examination of 2 probands showed a mild atrophy of the whole brain and no ribbon sign. The electroencephalography (EEG) did not show typical triphasic waves. Both cases had a positive cerebrospinal fluid (CSF) 14-3-3 protein and PrP D178N /Met-129 mutation.All patients were given traditional sedatives or anti-anxiety and depression drugs which were with poor efficacy. Conclusions: The major clinical manifestations of FFI are sleep disorders accompanied by mental disorders. The clinical manifestations are similar among different individuals within one family, however, there is obvious clinical variability among different families. The neuroimaging examination shows a mild atrophy of the whole brain and no ribbon sign. There are no typical triphasic waves in EEG. Positive CSF 14-3-3 protein and PrP D178N /Met-129 mutation are common in FFI. Traditional sedatives or anti-anxiety and depression drugs may have poor efficacy.

Familial fatal insomnia with atypical clinical features in a patient with D178N mutation and homozygosity for Met at codon 129 of the prion protein gene

Familial fatal insomnia (FFI) is fatal disorder characterized by damage to select thalamic nuclei, together with progressive insomnia and dysautonomia. In subjects carrying the D178N prion protein (PRNP) mutation, distinct phenotypes can be observed, depending on the methionine (Met) /valine (Val) codon 129 polymorphism. We report here a Chinese case of FFI with a D178N/Met129 genotype of the PRNP gene, who exhibited rapidly progressive dementia combined with behavioral disturbances and paroxysmal limb myoclonus. Our patient did not show refractory insomnia early in the disease course, nor demonstrate typical MRI and EEG alterations. There was remarkable family history of similar symptoms.