PMP22 and Charcot-Marie-Tooth disease type 1A: To investigate whether SM dosage is able to detect peripheral myelinopathy, we quantified SM in a well-known dysmyelinating inherited disorder, the CMT1A neuropathy (Figure 1A).14,31 In particular, homogenate of sciatic nerves from 30-day-old CMT1A rats and wild-type (WT) littermates were used.