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.

家族性致命性失眠症（FFI）是一种致命的疾病，其特征是特定丘脑核受损，伴有进行性失眠和自主神经功能障碍。在携带D178N朊蛋白（PRNP）突变的个体中，根据蛋氨酸（Met）/缬氨酸（Val）第129位密码子的多态性，可以观察到不同的表型。我们在此报告一例中国的家族性致命性失眠症病例，其PRNP基因具有D178N/Met129基因型，表现出快速进展的痴呆，伴有行为障碍和阵发性肢体肌阵挛。我们的患者在疾病早期没有出现难治性失眠，也没有表现出典型的磁共振成像（MRI）和脑电图（EEG）改变。有明显的类似症状家族史。