What is Mucopolysaccharidosis Type IIID (MPS3D)?
Mucopolysaccharidosis Type IIID is a rare genetic metabolic disorder. It is often also referred to as Sanfilippo D.
The disease usually presents itself post infancy, in early childhood anywhere between the ages of 2 and 6 years old.
A major defining symptom of this rare disease is global developmental delay and neurological deterioration.
Syndrome Synonyms:
MPS IIID; MPSIII; Mucopolysaccharidosis type III; N-acetylglucosamine-6-sulfatase Deficiency; Sanfilippo Syndrome
What are the gene causes of Mucopolysaccharidosis Type IIID (MPS3D)?
The syndrome is a lysosomal storage disease caused by a missing or deficient enzyme that is responsible for breaking down the large sugar molecule heparan sulfate. The buildup of these molecules in the body tissue triggers the symptoms of the syndrome. It is inherited in an autosomal recessive pattern, caused by a mutation in the GNS gene.
Autosomal recessive inheritance means an affected individual receives one copy of a mutated gene from each of their parents, giving them two copies of a mutated gene. Parents, who carry only one copy of the gene mutation will not generally show any symptoms but have a 25% chance of passing the copies of the gene mutations onto each of their children.
What are the main symptoms of Mucopolysaccharidosis Type IIID (MPS3D)?
Symptoms of the syndrome included aggressive behavior, developmental delay, and intellectual disability. Hyperactivity, seizure,s and an inability to sleep for more than a few hours at a time are also common symptoms.
Physical features of the syndrome include an upturned nasal tip, low-set ears, hearing loss, and problems with vision.
Possible clinical traits/features:
Absent speech, Asymmetric septal hypertrophy, Ovoid thoracolumbar vertebrae, Thickened ribs, Seizure, Autosomal recessive inheritance, Wide mouth, Short neck, Heparan sulfate excretion in urine, Hearing impairment, Hepatomegaly, Hirsutism, Hyperactivity, Depressed nasal bridge, Growth abnormality, Intellectual disability, Joint stiffness, Cellular metachromasia, Low-set ears, Anteverted nares, Dysphagia, Dysostosis multiplex, Dysarthria, Drooling, Flexion contracture, Diarrhea, Coarse hair, Coarse facial features, Progressive, Synophrys, Prominent forehead, Thick eyebrow, Frontal bossing, Splenomegaly, Recurrent upper respiratory tract infections, Sleep disturbance, Thick lower lip vermilion.
How is it diagnosed?
To find out if someone has a diagnosis of Mucopolysaccharidosis Type IIID, it is important to have a consultation and evaluation with a clinical genetic specialist. Specialists may also suggest specific genetic testing or other types of tests to help reach a diagnosis. FDNA’s AI technology can help speed up the diagnostic process by analyzing facial features and other health information.
