The Pathology of Primary Familial Brain Calcification: Implications for Treatment / 神经科学通报·英文版

Primary familial brain calcification (PFBC) is an inherited neurodegenerative disorder mainly characterized by progressive calcium deposition bilaterally in the brain, accompanied by various symptoms, such as dystonia, ataxia, parkinsonism, dementia, depression, headaches, and epilepsy. Currently, the etiology of PFBC is largely unknown, and no specific prevention or treatment is available. During the past 10 years, six causative genes (SLC20A2, PDGFRB, PDGFB, XPR1, MYORG, and JAM2) have been identified in PFBC. In this review, considering mechanistic studies of these genes at the cellular level and in animals, we summarize the pathogenesis and potential preventive and therapeutic strategies for PFBC patients. Our systematic analysis suggests a classification for PFBC genetic etiology based on several characteristics, provides a summary of the known composition of brain calcification, and identifies some potential therapeutic targets for PFBC.

Identification of a Novel Homozygous Splice-Site Mutation in that Causes Progressive Myoclonus Epilepsy with or without Renal Failure / 中华医学杂志(英文版)

<p><b>Background</b>Progressive myoclonus epilepsies (PMEs) comprise a group of rare genetic disorders characterized by action myoclonus, epileptic seizures, and ataxia with progressive neurologic decline. Due to clinical and genetic heterogeneity of PMEs, it is difficult to decide which genes are affected. The aim of this study was to report an action myoclonus with or without renal failure syndrome (EPM4) family and summarize the clinical and genetic characteristics of all reported EPM4 patients.</p><p><b>Methods</b>In the present study, targeted next-generation sequencing (NGS) was applied to screen causative genes in a Chinese PME family. The candidate variant was further confirmed by cosegregation analysis and further functional analysis, including the reverse transcription polymerase chain reaction and Western blot of the proband's muscle. Moreover, literature data on the clinical and mutational features of all reported EPM4 patients were reviewed.</p><p><b>Results</b>The gene analysis revealed a novel homozygous splicing mutation (c.995-1G>A) of the SCARB2 gene in two brothers. Further functional analysis revealed that this mutation led to loss function of the SCARB2 protein. The classification of the candidate variant, according to the American College of Medical Genetics and Genomics standards and guidelines and functional analysis, was pathogenic. Therefore, these two brothers were finally diagnostically confirmed as EPM4.</p><p><b>Conclusions</b>These present results suggest the potential for targeted NGS to conduct a more rapid and precise diagnosis for PME patients. A literature review revealed that mutations in the different functional domains of SCARB2 appear to be associated with the phenotype of EPM4.</p>

Mitochondrial DNA Haplogroups and the Risk of Sporadic Parkinson's Disease in Han Chinese / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Mitochondrial dysfunction is linked to the pathogenesis of Parkinson's disease (PD). However, the precise role of mitochondrial DNA (mtDNA) variations is obscure. On the other hand, mtDNA haplogroups have been inconsistently reported to modify the risk of PD among different population. Here, we try to explore the relationship between mtDNA haplogroups and sporadic PD in a Han Chinese population.</p><p><b>METHODS</b>Nine single-nucleotide polymorphisms, which define the major Asian mtDNA haplogroups (A, B, C, D, F, G), were detected via polymerase chain reaction-restriction fragment length polymorphism or denaturing polyacrylamide gel electrophoresis in 279 sporadic PD patients and 510 matched controls of Han population.</p><p><b>RESULTS</b>Overall, the distribution of mtDNA haplogroups did not show any significant differences between patients and controls. However, after stratification by age at onset, the frequency of haplogroup B was significantly lower in patients with early-onset PD (EOPD) compared to the controls (odds ratio [OR] =0.225, 95% confidence interval [CI]: 0.082-0.619, P = 0.004), while other haplogroups did not show significant differences. After stratification by age at examination, among subjects younger than 50 years of age: Haplogroup B also showed a lower frequency in PD cases (OR = 0.146, 95% CI: 0.030-0.715, P = 0.018) while haplogroup D presented a higher risk of PD (OR = 3.579, 95% CI: 1.112-11.523, P = 0.033), other haplogroups also did not show significant differences in the group.</p><p><b>CONCLUSIONS</b>Our study indicates that haplogroup B might confer a lower risk for EOPD and people younger than 50 years in Han Chinese, while haplogroup D probably lead a higher risk of PD in people younger than 50 years of age. In brief, particular Asian mtDNA haplogroups likely play a role in the pathogenesis of PD among Han Chinese.</p>

Analysis of CLCN1 gene mutations in 2 patients with myotonia congenita / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate chloride channel 1 (CLCN1) gene mutation and clinical features of 2 Chinese patients with myotonia congenita.</p><p><b>METHODS</b>Clinical data of a patient from a family affected with myotonia congenita in addition with a sporadic patient from Fujian province were analyzed. Exons of CLCN1 gene were amplified and sequenced.</p><p><b>RESULTS</b>The proband from the affected family was found to carry a c.1024G>A heterozygous missense mutation in exon 8, whilst the sporadic patient has carried a c.1292C>T heterozygous missense mutation in exon 11.</p><p><b>CONCLUSION</b>Detection of CLCN1 gene mutation is an effective method for the diagnosis of myotonia congenita. Exon 8 of CLCN1 gene may be a mutational hotspot in Chinese patients with myotonia congenita.</p>

Rapid diagnosis of spinal muscular atrophy using denaturing high-performance liquid chromatography / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To introduce the application of denaturing high-performance liquid chromatography (DHPLC) in the diagnosis of childhood type spinal muscular atrophy (SMA).</p><p><b>METHODS</b>Exon 7 and flanking area of survival motor neuron (SMN) gene were amplified by PCR in 1 standard sample, 25 normal individuals and 25 patients with SMA. The PCR products were then directly loaded onto the DHPLC system after denaturing and annealing. Different DNA segments were separated by changing the concentration of buffer A relative to that of buffer B.</p><p><b>RESULTS</b>Different DNA segments were separable on the DHPLC chromatogram. Three peaks including SMN1/SMN2 heteroduplex peak, SMN2 homoduplex peak and SMN1 homoduplex peak were detected in 23 out of 25 normal individuals. Only SMN1 homoduplex peak was detected in 2 normal individuals and the standard sample, indicating the deletion of SMN2 On the contrary, only the SMN2 homoduplex peak was detected in 22 out of 25 patients with SMA, indicating deletion of SMN1. The three peaks as those of normal individuals were detected in the other 3 patients, indicating no SMN1 or SMN2 deletion.</p><p><b>CONCLUSION</b>As a new technology for diagnosing SMA, DHPLC is sensitive, accurate, rapid and convenient.</p>

Quantitative studies on SMN1 gene and carrier testing of spinal muscular atrophy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To construct a method for detecting the copy number of survival of motor neuron 1 gene (SMN1) with single copy difference based on real-time fluorescence quantitative PCR, and to make practical use of the method for acquiring the data on SMN1 copy number in Chinese as well as for screening the carriers of spinal muscular atrophy (SMA) from healthy individuals and SMA families.</p><p><b>METHODS</b>Exon 7 and flanking area of SMN1 gene were amplified by real-time fluorescence quantitative PCR in 264 healthy individuals, in 1 standard sample having 2 SMN1 but having no SMN2, and in 88 parents of SMA patients. The samples for detecting were diluted to 30 ng/microL and the standard sample was diluted to 15 ng/microL, 30 ng/microL, 45 ng/microL, 60 ng/microL; the unknown samples and 4 standard samples with different concentrations were amplified at the same time, a standard curve could be drawn out according to the results of the 4 standard samples, then the copy number of samples could be calculated.</p><p><b>RESULTS</b>Of 88 parents' samples, 84 samples each had 1 copy of SMN1, and the rest 4 each had 2 copies of SMN1. Of 264 healthy individuals' samples, 5 samples each had only 1 copy of SMN1 (an indicator of definite gene carriers), 232 samples each had 2 copies of SMN1, 25 samples each had 3 copies of SMN1, and 2 samples each had 4 copies of SMN1. Of the samples of 32 members of SMA families, 2 samples each had only 1 copy of SMN1 indicating definite gene carriers, 25 samples each had 2 copies of SMN1, and 5 samples each had 3 copies of SMN1.</p><p><b>CONCLUSION</b>SMN1 copy number could be detected precisely by real-time fluorescence quantitative PCR; the screening of gene carriers could provide essential data for genetic counseling.</p>

Optimization of short tandem repeats and their application in prenatal diagnosis of spinal muscular atrophy / 中华神经科杂志

Objective To optimize the short tandem repeats(STR)which link closely to survival motor neuron(SMN)and have redundant polymorphism information contents,and to use these STR in the prenatal diagnosis of spinal muscular atrophy(SMA).Methods Eleven STR loci(D5S435,D5F153, DSF151,D5S637,D5S1413,D5S125,D5S464,D5S1556,DSF149,D5S351,MAP1B-5')were amplified by PCR.Then the PCR products were detected by polyacrylamide gel electrophoresis(PAGE)and analyzed by silver staining.STR loci were evaluated and optimized by their PIC values.PCR-PAGE and gene scan were combined to make genetic link analysis for SMA families based on the optimized STR.Results Three STR loci(D5S435,DSF149 and D5S351)were selected with 8,19 and 18 polymorphic fragments detected respectively in 100 normal individuals.Their PIC values were 0.84,0.91 and 0.92 respectively.Four carriers and 2 normal individuals were detected from 6 SMA families with linkage analysis by using the 3 STR.Conclusion This genetic diagnosis system based on the 3 STR loci can provide rapid prenatal diagnosis for SMA families,can eliminate maternal blood contamination,and also can discriminate carriers from normal individuals in the fetuses,which makes the prenatal diagnosis system of SMA perfect.