Marinesco-Sjögren syndrome (MSS)
General description
Marinesco-Sjögren syndrome (MSS) is a rare autosomal recessive multisystem disorder caused by biallelic pathogenic variants in the SIL1 gene. The SIL1 gene encodes a nucleotide exchange factor for BiP (immunoglobulin binding protein), which is the major endoplasmic reticulum (ER) chaperone involved in protein folding.
MSS is characterized by a classic triad of cerebellar ataxia with cerebellar atrophy, early-onset cataracts, and chronic myopathy. Patients often experience progressive muscle weakness, particularly in the lower extremities, along with hypotonia. Intellectual disability, ranging from mild to moderate, is common, as are speech impairments such as dysarthria and involuntary eye movements (nystagmus). Skeletal abnormalities, including short stature and scoliosis, may also be present. Additionally, hypergonadotropic hypogonadism can result in delayed or absent puberty.
References
- Reinhold, Anke, et al. "MR imaging features in Marinesco-Sjögren syndrome: severe cerebellar atrophy is not an obligatory finding." American journal of neuroradiology 24.5 (2003): 825-828.
Cerebellar hypoplasia
MRI demonstrates bilateral cerebellar hypoplasia. This description must be refined later.
Cortical hyperintensity of cerebellum
The salient neuroimaging features of this syndrome encompass T2WI/FLAIR hyperintensity within the cerebellar cortex. Similar imaging findings are also seen in PMM2-congenital disorder of glycosylation (PMM2-CDG).
Cerebral white matter lesion
White matter abnormalities may be present in the supratentorial compartment, manifesting as leukoencephalopathy with periventricular and juxtacortical focal lesions that appear focally hyperintense on T2-weighted and FLAIR images.
Anterior pituitary hypoplasia
Morphologic changes of the pituitary gland appear to be common findings in MSS patients. An apparently small anterior pituitary gland has been observed in multiple patients.
Absence of the posterior pituitary bright spot
The absence of the posterior pituitary bright spot on T1-weighted images represents a frequent finding.