The M1627K mutation in the D4S4-5 region may also affect a residue involved in interacting with the IFM inactivation motif. This would explain the observed alteration of inactivation and the broadening of a window current. One of the affected families with the R996C mutation, pedigree 12, has a single individual who also has the V1298D mutation. The individual in this family with the compound mutation is the most severely affected, suggesting that the R996C mutation may cause a less severe phenotype. The less severe phenotype of the pedigree 4 family is in concordance with this theory. It is unclear how the R996C mutation affects channel function. Diagnosis
Hematological, biochemical and metabolic investigations on blood and urine between attacks are normal, as are karyotyping and EKG recordings. EKG recordings during attacks show sinus tachycardia. CT, MRI, EMG and nerve conduction studies produce normal results. EEG recordings are normal between attacks but show early-onset tachycardia during attacks. On the Neuropathic Pain Questionnaire patients indicated that pain during attacks is extremely unpleasant and typically felt deep, though also superficial on occasion. Aside from presentation of typical symptoms (see Signs and symptoms above) mutation of the gene SCN9A aids in appropriate diagnosis as this gene is mutated in 8 of 14 studied families. Treatment
Carbamazepine is at least partly effective at reducing the number or severity of attacks in the majority of PEPD patients. High doses of this drug may be required, perhaps explaining the lack of effect in some individuals.
Elastosis perforans serpiginosa is a unique perforating disorder characterized by transepidermal elimination of elastic fibers and distinctive clinical lesions, which are serpiginous in distribution and can be associated with specific diseases. See also
List of cutaneous conditions
Poikiloderma vasculare atrophicans

References


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