Long-term clinical course of a patient with mucopolysaccharidosis type IIIB

Area of Science:

• Genetics
• Biochemistry
• Pediatrics

Background:

• Mucopolysaccharidosis type III (MPS III) is a rare lysosomal storage disorder.
• MPS IIIB specifically stems from a deficiency in the alpha-N-acetyl-D-glucosaminidase (NAGLU) enzyme.
• Clinical manifestations typically emerge between ages 2-6 years, including behavioral changes and cognitive decline.

Purpose of the Study:

• To present a case of MPS IIIB with a long-term follow-up.
• To emphasize the diagnostic challenges and importance of clinical course evaluation in MPS IIIB.
• To discuss the implications of early diagnosis for at-risk families.

Main Methods:

• Case report of a patient with MPS IIIB.
• Long-term clinical observation and follow-up.
• Genetic analysis identifying compound heterozygous variants in the NAGLU gene (c.1444C>T and c.1675G>T).

Main Results:

• The patient exhibited normal development until age 3, followed by behavioral changes, sleep disturbances, and motor dysfunction.
• Hospitalizations occurred due to recurrent pneumonia and epilepsy, alongside severe cognitive impairment.
• Genetic testing revealed compound heterozygous variants (p.R482W and p.D559Y) in the NAGLU gene.

Conclusions:

• MPS IIIB diagnosis can be challenging due to less pronounced facial and skeletal features, underscoring the value of long-term clinical monitoring.
• While no definitive therapies exist, early and accurate diagnosis is crucial for family planning and genetic counseling.
• This case highlights the progressive nature of MPS IIIB and the importance of comprehensive patient evaluation.