Development and longitudinal neurocognitive functioning in mucopolysaccharidosis type IIIC: a case study

Area of Science:

• Biochemistry
• Genetics
• Neuroscience

Background:

• Mucopolysaccharidosis type IIIC (MPS IIIC) is a rare genetic disorder.
• It is caused by mutations in the HGSNAT gene, leading to neurodegeneration.
• Clinical presentation and progression of MPS IIIC can vary significantly.

Purpose of the Study:

• To analyze the neurocognitive, medical, and developmental functioning of a 9-year-old girl with MPS IIIC.
• To investigate the correlation between genetic profile, enzyme levels, and clinical presentation.
• To highlight the variability in MPS IIIC progression.

Main Methods:

• Case study analysis.
• Genetic testing for HGSNAT gene variants.
• Neuropsychological assessment.
• Brain magnetic resonance imaging (MRI).

Main Results:

• The patient has a homozygous pathogenic HGSNAT variant (c.1872C>A) but a milder clinical course than expected.
• Moderate intellectual disability was observed, with a stable developmental age for 3 years.
• Cognitive skills remained stable, except for a decline in working memory; MRI showed no abnormalities.

Conclusions:

• MPS IIIC progression is complex and highly variable, even with severe genetic markers.
• Early diagnosis, regular monitoring, and a multidisciplinary approach are essential for managing MPS IIIC.
• Individual variability must be considered in predicting MPS IIIC outcomes.