SUCLA2-deficiency leads to inefficient yield of energy from food. The function of all parts of the body that need a lot of energy is hampered. As a consequence the muscles are weak and muscle coordination is poor. Therefore, there is only little and very slow development of motor abilities. As a further consequence sucking and swallowing is weak and uncoordinated and weight gain and growth are impaired. Mental development seems to be impaired. However, most children do not hear very well or even are deaf. Further hampered by their muscular problems, they do not acquire active language. If provided with hearing aids (or cochlear implants) understanding of language is good; communication can be facilitated by providing the children with adapted electronic devices (e.g. tablets using pictograms).
Life expectancy varies considerably: some children do not survive infancy; others live into adulthood. Pulmonary problems and troubles with central regulation of breathing and/or heart action (caused by progressive involvement of the basal ganglia) are common causes of death. SUCLA2-deficiency is a very rare disorder. Nevertheless, there are some isolated populations with high incidences (e.g. in the Faroe Islands where one in 1:500 neonates is affected). It is an autosomal recessively inherited disorder. Thus, when both parents are (clinically healthy) carriers, one out of four children of this couple is at risk for being affected by the disorder.