Symptoms usually occur in early or late
childhood. Strabismus is often present and the cause of visual difficulties.
Other clinical manifestations include night blindness, cataracts, and
retinitis pigmentosa occurring during childhood. There is a decreased level
of gonadotrophic hormone production because of hypogonadism, which
contributes to delay of onset of puberty and development of secondary sex
characteristics. Males usually are infertile and may develop
pseudogynecomastia. Females have amenorrhea and fail to develop breasts.
Other signs include mental retardation, ataxia, muscle rigidity, and spastic
paraplegia. Renal disease is common because of abnormalities in the
structure or function of the kidneys. In some rare cases, diabetes,
congenital heart defects, and breathing problems may occur.