Most people with NFU1 deficiency become sick very early in life—usually as newborns or within the first year of life. The condition is severe and often leads to death before the age of two. In newborns, the most common signs are being unusually sleepy, and feeding difficulties. As time goes on, babies often lose skills they had already learned. About 70% of affected children also develop pulmonary hypertension, a condition in which the pressure inside the blood vessels of the lungs is abnormally high. As a result, the heart has to push blood harder to get it to the lungs. Brain MRI often show damage in the white matter (leukoencephalopathy), sometimes with early-forming holes (cavitation) or cysts. There are also rare cases where symptoms initiate later, and the affected individuals survive much longer—even into adulthood. These individuals tend to develop stiff, weak legs (spastic paraplegia), nerve damage that affects movement and sensation, and varying degree of developmental delay. Importantly, none of the patients with this later-onset form have developed pulmonary hypertension.
NFU1