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We currently offer direct PCR-based DNA sequencing analysis for the mutations in exon 12 of SCN4A gene that cause Hypokalemic Periodic Paralysis (HOPP) phenotype, HOPP-2. At least four mutations (R669H, R672S, R672G and R672H) have been reported in exon 12 of SCN4A gene that cause HOPP clinical symptoms.
Our sequencing analysis will detect all the reported mutations and any new mutations in exon 12. SCN4A mutations have been reported in about 12% of all patients with HOPP phenotype. 1,2,3
Sample Preparation: Sample Preparation (PDF)
Results of DNA analysis will be communicated in a written report to the referring professional.
Analysis is appropriate for the study of affected patients, for diagnostic confirmation of a presumed affected individual, and for presymptomatic individuals with a family history of HOPP.
Note: Because of the variation in clinical phenotypic expression we require that genetic counseling be obtained prior to request for presymptomatic testing.
1. D. Sternberg et al., (2001) Hypokalaemic paeriodic paralysis type 2 caused by mutations at condon 672 in the muscle sodium channel gene SCN4A. Brain, 124(6)
2. A. Struyk, et al., (2000) The human skeletal muscle Na channel mutation R669H associated with hypokalemic periodic paralysis enhances slow inactivation. J. Neurosci. 20(23):8610-7.
3. D. Sternberg et al., (2002) Hypokalemic periodic paralysis. GeneReviews, April 30, 2002, www.genereviews.org.
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