A syndrome with characteristics of immune deficiency and neurological disorders in females and neonatal death in males. The syndrome has been described in only one family with nine affected individuals (five males and four females) spanning two generations. Symptomatic females present slowly progressive proximal muscle weakness, leg hyperreflexia, pes cavus, increased muscle tone in the legs, poor bladder function, static reduced night vision and frequent sinopulmonary infections associated with IgG2 deficiency. Males present with low birth weight and severe hypotonia that leads to death in the neonatal period. The gene locus has been mapped to Xq26-qter.

Autosomal recessive spastic paraplegia-89 (SPG89) is characterized by symptom onset in the first years of life. Affected individuals show delayed motor development with abnormal spastic gait and hyperreflexia of the lower limbs. Some patients may have mildly impaired intellectual development or learning difficulties (Deng et al., 2023). For a discussion of genetic heterogeneity of autosomal recessive SPG, see SPG5A (270800).