What are the genetic changes related to hereditary sensory and autonomic neuropathy type IE ?
HSAN IE is caused by mutations in the DNMT1 gene. This gene provides instructions for making an enzyme called DNA (cytosine-5)-methyltransferase 1. This enzyme is involved in DNA methylation, which is the addition of methyl groups, consisting of one carbon atom and three hydrogen atoms, to DNA molecules. In particular, the enzyme helps add methyl groups to DNA building blocks (nucleotides) called cytosines.  DNA methylation is important in many cellular functions. These include determining whether the instructions in a particular segment of DNA are carried out or suppressed (gene silencing), regulating reactions involving proteins and fats (lipids), and controlling the processing of chemicals that relay signals in the nervous system (neurotransmitters). DNA (cytosine-5)-methyltransferase 1 is active in the adult nervous system. Although its specific function is not well understood, the enzyme may help regulate nerve cell (neuron) maturation and specialization (differentiation), the ability of neurons to migrate where needed and connect with each other, and neuron survival.  DNMT1 gene mutations that cause HSAN IE reduce or eliminate the enzyme's methylation function, resulting in abnormalities in the maintenance of the neurons that make up the nervous system. However, it is not known how the mutations cause the specific signs and symptoms of HSAN IE.