Inheritance: autosomal recessive
Chromosome affected: 5q31, possibly other foci
Gene affected: SIL1 (SIL1 homolog, endoplasmic reticulum chaperone)
Clinical features:
(1) short stature
(2) microcephaly
(3) variable facial dysmorphism
(4) congenital or early-onset cataracts
(5) microcornea
(6) nystagmus
(7) optic atrophy
(8) hearing impairment
(9) skeletal deformities (scoliosis, kyphosis, short metatarsals and metacarpals, other)
(10) intellectual disability with delay in psychomotor development
(11) hypotonia and muscle weakness
(12) spasticity
(13) chronic myopathy with elevated serum CK
(14) cerebellar atrophy with cerebellar ataxia
(15) seizures
(16) variable peripheral neuropathy
(17) hypogonadism
(18) variable leukoencephalopathy
(19) variable diabetes mellitus
The differential diagnosis of MSS includes the CCFDN syndrome.
