Importantly,HSAN V patients, differently from HSAN IV patients, while displaying a similarcongenital insensitivity to pain, show no mental retardation nor other neurologicaland cognitive deficits [29], suggesting that neurodevelopmental effects on NGF targetneurons, including sensory neurons, are probably minor in HSAN V patients. Here, NGF is linked to hereditary sensory and autonomic neuropathy type 4.