X-linked congenital ataxia (SCAX1; OMIM; OMIM #302500) is caused by a mutation in the ATP2B3 gene. A gene is a carrier of hereditary information. All genes together are responsible for the function and appearance of the body. A gene consists of different letters, like a word. When a mutation occurs one of these letters changes and the word becomes incorrect similar to a spelling mistake. Consequently, the gene becomes illegible to the body and this might lead to disease.
The ATP2B3 gene has a vital role in normal functioning of the cerebellum. The cerebellum consists of neurons which interact with each other by chemical and electrical signaling (synaptic neurotransmission). The ATP2B3 gene codes for a part of a plasma membrane calcium pump. Calcium in neurons is vital to processes such as synaptic neurotransmission and neuronal development. When this pump does not work correctly (due to a mutation) the neurons do not develop or function normally. When someone (a male) has a mutation in ATP2B3, it can be newly arisen or it can be inherited from a healthy carrier mother. Each male child of a mother with a mutation in ATP2B3 has a 50% chance of being affected; this is called X-linked recessive mode of inheritance.
ATP2B3