Of note, exome sequencing was negative for other genetic variants that are known to cause CMT and a lower motor neuron disease phenotype; this included the HSPB, BSCL2, GARS, DCTN1, SLC5A7, FBX038, IGHMBP2, ATP7A, and SETX genes. This evidence concerns the gene IGHMBP2 and motor neuron disorder.