[Genetic distribution in Chinese patients with hereditary peripheral neuropathy]

OBJECTIVE

To analyze the distribution characteristics of hereditary peripheral neuropathy (HPN) pathogenic genes in Chinese Han population, and to explore the potential pathogenesis and treatment prospects of HPN and related diseases.

METHODS

Six hundred and fifty-six index patients with HPN were enrolled in Peking University Third Hospital and China-Japan Friendship Hospital from January 2007 to May 2022. The PMP22 duplication and deletion mutations were screened and validated by multiplex ligation probe amplification technique. The next-generation sequencing gene panel or whole exome sequencing was used, and the suspected genes were validated by Sanger sequencing.

RESULTS

Charcot-Marie-Tooth (CMT) accounted for 74.3% (495/666) of the patients with HPN, of whom 69.1% (342/495) were genetically confirmed. The most common genes of CMT were PMP22 duplication, MFN2 and GJB1 mutations, which accounted for 71.3% (244/342) of the patients with genetically confirmed CMT. Hereditary motor neuropathy (HMN) accounted for 16.1% (107/666) of HPN, and 43% (46/107) of HPN was genetically confirmed. The most common genes of HMN were HSPB1, aminoacyl tRNA synthetases and SORD mutations, which accounted for 56.5% (26/46) of the patients with genetically confirmed HMN. Most genes associated with HMN could cause different phenotypes. HMN and CMT shared many genes (e.g. HSPB1, GARS, IGHMBP2). Some genes associated with dHMN-plus shared genes associated with amyotrophic lateral sclerosis (KIF5A, FIG4, DCTN1, SETX, VRK1), hereditary spastic paraplegia (KIF5A, ZFYVE26, BSCL2) and spinal muscular atrophy (MORC2, IGHMBP, DNAJB2), suggesting that HMN was a continuum rather than a distinct entity. Hereditary sensor and autosomal neuropathy (HSAN) accounted for a small proportion of 2.6% (17/666) in HPN. The most common pathogenic gene was SPTLC1 mutation. TTR was the main gene causing hereditary amyloid peripheral neuropathy. The most common types of gene mutations were p.A117S and p.V50M. The symptoms were characterized by late-onset and prominent autonomic nerve involvement.

CONCLUSION

CMT and HMN are the most common diseases of HPN. There is a large overlap between HMN and motor-CMT2 pathogenic genes, and some HMN pathogenic genes overlap with amyotrophic lateral sclerosis, hereditary spastic hemiplegia and spinal muscular atrophy, suggesting that there may be a potential common pathogenic pathway between different diseases.

[Diagnostic value of tremor analysis in identifying the early Parkinson's syndrome]

OBJECTIVE

To investigate the diagnostic value of tremor analysis in early stages of Parkinson's syndrome, when the clinical symptoms of tremor onset are not unilaterally often able for a definite diagnosis to be made.

METHODS

We included 70 patients with unilateral tremor, under 45 years old and disease duration within 3 years enrolled in Peking University Third Hospital from January, 2014 to December 2015. We recorded clinical features, unified Parkinson's disease rating scale (UPDRS)-III, non-motor symptom (NMS) scores. Tremor analysis and transcranial sonography were performed for all the patients. Based on the results of tremor analysis, we arbitrarily divided the patients into 3 groups: (1) The patients with classical Parkinson's syndrome manifestations on one side (25 cases); (2) The patients with classical Parkinson's syndrome manifestations on both sides (15 cases); (3) The patients with no classical Parkinson's syndrome manifestations (30 cases). The patients were monitored every 6 months to 3 years, until the final diagnosis was made.

RESULTS

There was no significant difference in age, gender distribution, Hamilton depression scale (HAMD) scores and H-Y scores among the three groups (P>0.05). The average UPDRS-III motor scores of the three groups were significantly different (P=0.001), with 18.23, 18.79 and 14.67, respectively. The average scores of NMS were significantly different, with 15.81, 17.07 and 9.90, respectively (P<0.001). The positive rates of transcranial sonography (TCS) in the three groups were 48.0%, 60.0% and 26.67%, with no significant difference (P=0.702). After three years of follow-up, 35 patients (50%) met the diagnostic criteria of Parkinson's disease of International Parkinson and Movement Disorder Society (MDS) in 2015, 19 patients (27.1%) met the criteria of idiopathic tremor, and 7 patients (10%) met the criteria of Parkinson's plus syndrome. The sensitivity and specificity of tremor analysis for early diagnosis of Parkinson's disease were 82.8% and 68.6%, respectively. Compared with TCS, the sensitivity and specificity of TCS were 65.7% and 62.9%. There were consistency (Kappa=0.568) and significant difference (P=0.031) between the two methods.

CONCLUSION

Tremor analysis is sensitive and a superior way in identifying early Parkinson's syndrome patients with tremor dominant manifestation. The combination of non-motor symptoms and transcranial sonography are also needed at diagnosis.