Article

Practice parameter: the evaluation of distal symmetric polyneuropathy: the role of laboratory and genetic testing (an evidence-based review). Report of the American Academy of Neurology, the American Association of Neuromuscular and Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation. PM R

Louisiana State University Health Sciences Center, New Orleans, USA.
PM&R (Impact Factor: 1.66). 02/2009; 1(1):5-13. DOI: 10.1016/j.pmrj.2008.11.010
Source: PubMed

ABSTRACT Distal symmetric polyneuropathy (DSP) is the most common variety of neuropathy. Since the evaluation of this disorder is not standardized, the available literature was reviewed to provide evidence-based guidelines regarding the role of laboratory and genetic tests for the assessment of DSP.
A literature review using MEDLINE, EMBASE, Science Citation Index and Current Contents was performed to identify the best evidence regarding the evaluation of polyneuropathy published between 1980 and March 2007. Articles were classified according to a four-tiered level of evidence scheme and recommendations were based upon the level of evidence.
1. Screening laboratory tests may be considered for all patients with polyneuropathy (Level C). Those tests that provide the highest yield of abnormality are blood glucose, serum B12 with metabolites (methylmalonic acid with or without homocysteine) and serum protein immunofixation electrophoresis (Level C). If there is no definite evidence of diabetes mellitus by routine testing of blood glucose, testing for impaired glucose tolerance may be considered in distal symmetric sensory polyneuropathy (Level C). 2. Genetic testing is established as useful for the accurate diagnosis and classification of hereditary neuropathies (Level A). Genetic testing may be considered in patients with cryptogenic polyneuropathy who exhibit a hereditary neuropathy phenotype (Level C). Initial genetic testing should be guided by the clinical phenotype, inheritance pattern, and electrodiagnostic (EDX) features and should focus on the most common abnormalities which are CMT1A duplication/HNPP deletion, Cx32 (GJB1), and MFN2 mutation screening. There is insufficient evidence to determine the usefulness of routine genetic testing in patients with cryptogenic polyneuropathy who do not exhibit a hereditary neuropathy phenotype (Level U).

Download full-text

Full-text

Available from: James F Howard, Aug 22, 2015
0 Followers
 · 
258 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Charcot-Marie-Tooth (CMT) disease or hereditary motor and sensory neuropathy (HMSN) is a genetically heterogeneous group of conditions that affect the peripheral nervous system. The disease is characterized by degeneration or abnormal development of peripheral nerves and exhibits a range of patterns of genetic transmission. In the majority of cases, CMT first appears in infancy, and its manifestations include clumsiness of gait, predominantly distal muscular atrophy of the limbs, and deformity of the feet in the form of foot drop. It can be classified according to the pattern of transmission (autosomal dominant, autosomal recessive, or X linked), according to electrophysiological findings (demyelinating or axonal), or according to the causative mutant gene. The classification of CMT is complex and undergoes constant revision as new genes and mutations are discovered. In this paper, we review the most efficient diagnostic algorithms for the molecular diagnosis of CMT, which are based on clinical and electrophysiological data.
    BioMed Research International 10/2009; 2009(5):985415. DOI:10.1155/2009/985415 · 2.71 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Whole-genome sequencing may revolutionize medical diagnostics through rapid identification of alleles that cause disease. However, even in cases with simple patterns of inheritance and unambiguous diagnoses, the relationship between disease phenotypes and their corresponding genetic changes can be complicated. Comprehensive diagnostic assays must therefore identify all possible DNA changes in each haplotype and determine which are responsible for the underlying disorder. The high number of rare, heterogeneous mutations present in all humans and the paucity of known functional variants in more than 90% of annotated genes make this challenge particularly difficult. Thus, the identification of the molecular basis of a genetic disease by means of whole-genome sequencing has remained elusive. We therefore aimed to assess the usefulness of human whole-genome sequencing for genetic diagnosis in a patient with Charcot-Marie-Tooth disease. We identified a family with a recessive form of Charcot-Marie-Tooth disease for which the genetic basis had not been identified. We sequenced the whole genome of the proband, identified all potential functional variants in genes likely to be related to the disease, and genotyped these variants in the affected family members. We identified and validated compound, heterozygous, causative alleles in SH3TC2 (the SH3 domain and tetratricopeptide repeats 2 gene), involving two mutations, in the proband and in family members affected by Charcot-Marie-Tooth disease. Separate subclinical phenotypes segregated independently with each of the two mutations; heterozygous mutations confer susceptibility to neuropathy, including the carpal tunnel syndrome. As shown in this study of a family with Charcot-Marie-Tooth disease, whole-genome sequencing can identify clinically relevant variants and provide diagnostic information to inform the care of patients.
    New England Journal of Medicine 03/2010; 362(13):1181-91. DOI:10.1056/NEJMoa0908094 · 54.42 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The X-linked form of Charcot-Marie-Tooth disease (CMTX) is the second most common form of this genetically heterogeneous inherited peripheral neuropathy. CMT1X is caused by mutations in the GJB1 gene. Most of the mutations causative for CMT1X are missense mutations. In addition, a few disease causative nonsense mutations and frameshift deletions that lead to truncated forms of the protein have also been reported to be associated with CMT1X. Previously, there have been reports of patients with deletions of the coding sequence of GJB1; however, the size and breakpoints of these deletions were not assessed. Here, we report five patients with deletions that range in size from 12.2 to 48.3 kb and that completely eliminate the entire coding sequence of the GJB1 gene, resulting in a null allele for this locus. Analyses of the breakpoints of these deletions showed that they are nonrecurrent and that they can be generated by different mechanisms. In addition to PMP22, GJB1 is the second CMT gene for which both point mutations and genomic rearrangements can cause a neuropathy phenotype, stressing the importance of CMT as a genomic disorder.
    Neurogenetics 10/2010; 11(4):465-70. DOI:10.1007/s10048-010-0247-4 · 2.66 Impact Factor
Show more