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Variant profile of Brazilian patients with Sanfilippo syndrome type B

Alice Brinckmann Oliveira Netto1, Ana Carolina Brusius-Facchin2, Kristiane Michelin-Tirelli3

  • 1Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Genética e Biologia Molecular, Porto Alegre, RS, Brazil.

Genetics and Molecular Biology
|June 30, 2026
PubMed

Insights

Mucopolysaccharidosis type IIIB (MPS IIIB) is a genetic disorder. Researchers identified new gene variants in Brazilian patients, improving understanding and diagnostic strategies for this rare disease.

Area of Science:

  • Genetics
  • Biochemistry
  • Rare Diseases

Background:

  • Mucopolysaccharidosis type IIIB (MPS IIIB) is a lysosomal storage disorder.
  • It results from variants in the NAGLU gene, causing heparan sulfate accumulation.
  • MPS IIIB is also known as Sanfilippo syndrome type B.

Purpose of the Study:

  • To characterize the genetic landscape of MPS IIIB in Brazilian patients.
  • To identify novel NAGLU gene variants.
  • To inform diagnostic and screening strategies for MPS IIIB in Brazil.

Main Methods:

  • Biochemical tests including NAGLU enzyme activity and urinary glycosaminoglycans (GAG) analysis.
  • Molecular analysis of the NAGLU gene using Sanger sequencing or Targeted Next-Generation Sequencing.
  • In silico prediction of pathogenicity for novel variants.

Main Results:

  • Analysis of 27 Brazilian MPS IIIB patients (2014-2022).
  • Identified 49 variants across patient alleles, including 22 distinct variants.
  • Discovered two novel missense variants (p.Gly79Arg and p.Leu598Pro), predicted as deleterious.
  • Detected 90.7% of expected mutant alleles, showing variant heterogeneity and a high frequency of missense variants.

Conclusions:

  • The study provides a comprehensive characterization of the Brazilian MPS IIIB genetic spectrum.
  • Novel variants were identified, expanding the known mutational landscape.
  • Findings are crucial for developing targeted diagnostic and screening approaches for MPS IIIB.

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