Mucopolysaccharidosis, Type IIIC

What is Mucopolysaccharidosis, Type IIIC?

It is a subtype of Mucopolysaccharidosis, Type III. There are four subtypes of this form of the syndrome. Known as a form of childhood dementia the syndrome causes brain damage that is eventually fatal.

Type C is the mildest subtype of the syndrome. It’s symptoms are less severe than the other three types, and affected individuals generally have a higher life expectancy, usually into early adulthood.

This syndrome is also known as:
Acetyl-coa:alpha-glucosaminide N-acetyltransferase Deficiency MPS IIIA-D Mps Iiic MPSIII Mucopolysaccharidosis III Mucopolysaccharidosis type III Sanfilippo Syndrome C

What gene changes cause Mucopolysaccharidosis, Type IIIC?

Changes in the HGSNAT gene are responsible for causing the syndrome.

It is inherited in an autosomal recessive manner.

What are the main symptoms of Mucopolysaccharidosis, Type IIIC?

Symptoms of the syndrome do not usually present at birth. One of the first symptoms recognised is developmental delay which is usually identified in early childhood and before the age of 6. From this age the symptoms become more severe, and intellectual ability starts to decline. Behavioral issues, including hyperactivity, are also a major symptom and often one of the first identified. Sleeping issues are also common. Affected individuals will also experience speech delay which gets progressively worse with age.

Physical features of the syndrome include coarse hair, excessive hair growth, coarse facial features, and hearing and vision loss. Enlarged organs such as the liver and/or spleen and hernias are also features of the syndrome.

Possible clinical traits/features:
Dysphagia, Dysostosis multiplex, Everted lower lip vermilion, Coarse hair, Coarse facial features, Dense calvaria, Motor delay, Dolichocephaly, Diarrhea, Hepatomegaly, Hearing impairment, Heparan sulfate excretion in urine, Hyperactivity, Hernia, Hirsutism, Growth abnormality, Thickened ribs, Seizure, Ovoid thoracolumbar vertebrae, Autosomal recessive inheritance, Rod-cone dystrophy, Asymmetric septal hypertrophy, Intellectual disability, Loss of speech, Cellular metachromasia, Motor deterioration, Joint stiffness, Kyphoscoliosis, Variable expressivity, Sleep disturbance, Recurrent upper respiratory tract infections, Synophrys, Splenomegaly

How does someone get tested for Mucopolysaccharidosis, Type IIIC?

The initial testing for Mucopolysaccharidosis, Type IIIC can begin with facial analysis screening with FDNA’s AI technology, which can identify the key markers of the syndrome and outline the need for further testing.

Based on clinical consultation with a genetic professional, different options for genetic testing will be proposed.

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