Sialidosis is a severe inherited disorder that affects many organs and tissues, including the nervous system.
This disorder is divided into two types depending on the age of the onset of the disease:
Sialidosis type I:
also referred to as cherry-red spot myoclonus syndrome, is the less severe form of this condition.People with type I develop signs and
symptoms of sialidosis in their teens or twenties.
Sialidosis type II:
the more severe type of the disorder, is further divided into
Congenital sialidosis type II
can develop before birth. Individuals with congenital sialidosis type II usually are stillborn or die soon after birth.
Infantile sialidosis type II
the signs and symptoms are slightly less severe and begin within the first year of life.
The juvenile form
has the least severe signs and symptoms of the different forms of sialidosis type II.
What are the symptoms of sialidosis?
Cherry red spots on ophthalmology evaluation, coarse facial features, hepatosplenomegaly, dysostosis multiplex, hydrops, myoclonus, intellectual
disability, dark red spots on the skin (angiokeratomas).
How common is the disease?
Sialidosis is more common in people with Italian ancestry.
What genes are related to sialidosis?
gene provides instructions for making an enzyme called neuraminidase 1 (NEU1), which is found in lysosomes. Mutations in the NEU1 gene lead to a shortage
of the NEU1 enzyme. When this enzyme is lacking, sialic acid-containing compounds accumulate inside lysosomes.
How do people inherit sialidosis?
This condition is inherited in an autosomal recessive pattern.
How is Sialidosis diagnosed?
Sialidosis is diagnosed based on thorough clinical evaluation, identification of characteristic symptoms, detailed patient history. A urine test is
followed up by blood tests and a skin biopsy. These tests can reveal low levels of the enzyme alpha-neuraminidase in blood and skin tissue. Diagnosis can
be confirmed by molecular genetic testing detecting mutations in the NEU1 gene.
Prenatal diagnosis can be performed through chorionic villus biopsy or amniocentesis, if the mutations in the family are known.