Investigators from Aachen University, Germany, and multiple centers in Europe, UK, USA, Turkey and Argentina, report the results of SIL1 mutation analysis in 62 patients presenting with early-onset ataxia, cataracts and myopathy, the characteristic Marinesco-Sjogren syndrome triad. The mutation detection rate was 60% (15/25) among patients with the characteristic triad and <3% (1/37) in the group with more variable phenotypic presentation. Sixteen unrelated families had a total of 19 different SIL1 mutations. SIL1 mutations are invariably associated with a combination of cerebellar ataxia and chronic myopathy. Cataracts were sometimes absent in infants but were observed in all patients beyond the age of 7 years. Six patients with SIL1 mutations had no intellectual disability, and most patients had somatic growth retardation, skeletal abnormalities and pyramidal tract signs. SIL1 is the major Marinesco-Sjogren gene and the data collected broaden the SIL1 mutation spectrum. 
COMMENTARY. The alternative term for Marinesco-Sjogren syndrome is “hereditary oligophrenic cerebello-lental degeneration.” Organs involved are the cerebellum, eye lens, and muscles. Diagnostic characteristics are cerebellar ataxia, MRI evidence of cerebellar vermis atrophy, cataracts, mental retardation, and progressive myopathy. Associated abnormalities are small stature, brittle fingernails, sparse hair, dysarthria, hypergonadotropic hypogonadism, and scoliosis [2, 3].