Looks like there is a definitive test:
Found this:-We report a 14-month-old toddler. The child presented with symptoms such as unsteadiness and ataxic gait along with decreased motor and sensory action potentials of the limbs. As the father of the child was diagnosed with Charcot-Marie-Tooth 1A disease, a genetic analysis of the PMP22 GENE was performed confirming the diagnosis of Charcot- Marie-Tooth 1A in the child, too.
This case underscores the significance of an appropriate neurological assessment.