MedGen

Sialidosis is an autosomal recessive disorder characterized by the progressive lysosomal storage of sialylated glycopeptides and oligosaccharides caused by a deficiency of the enzyme neuraminidase. Common to the sialidoses is the accumulation and/or excretion of sialic acid (N-acetylneuraminic acid) covalently linked ('bound') to a variety of oligosaccharides and/or glycoproteins (summary by Lowden and O'Brien, 1979). The sialidoses are distinct from the sialurias in which there is storage and excretion of 'free' sialic acid, rather than 'bound' sialic acid; neuraminidase activity in sialuria is normal or elevated. Salla disease (604369) is a form of 'free' sialic acid disease. Classification Lowden and O'Brien (1979) provided a logical nosology of neuraminidase deficiency into sialidosis type I and type II. Type I is the milder form, also known as the 'normosomatic' type or the cherry red spot-myoclonus syndrome. Sialidosis type II is the more severe form with an earlier onset, and is also known as the 'dysmorphic' type. Type II has been subdivided into juvenile and infantile forms. Other terms for sialidosis type II are mucolipidosis I and lipomucopolysaccharidosis. [from OMIM]

Steatosis is a term used to denote lipid accumulation within hepatocytes. [from HPO]

Spinocerebellar ataxia with axonal neuropathy type 1 (SCAN1) is characterized by late-childhood-onset slowly progressive cerebellar ataxia and distal sensorimotor axonal neuropathy. Gaze nystagmus and dysarthria usually develop after the onset of ataxic gait. As the disease advances, pain and touch sensation in the hands and feet become impaired; vibration sense is lost in hands and lower thighs. Individuals with advanced disease develop a steppage gait and pes cavus and eventually become wheelchair dependent. Cognitive dysfunction – present in some – manifests as mild intellectual disability and poor executive function. To date only seven affected individuals have been described from three apparently unrelated consanguineous families (one from Saudi Arabia and two from Oman); therefore, it is likely that the full phenotypic spectrum of this disorder is not yet known. [from GeneReviews]

Nonalcoholic fatty liver disease (NAFLD) is the presence of hepatic steatosis with or without inflammation and fibrosis that is not caused by alcohol. NAFLD is subdivided into nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). [from SNOMEDCT_US]