Disease progression in Sanfilippo type B: Case series of Brazilian patients.

Mucopolysaccharidosis type IIIB (MPS IIIB) is caused by deficiency of alpha-N-acetylglucosaminidase, leading to storage of heparan sulphate. The disease is characterized by intellectual disability and hyperactivity, among other neurological and somatic features. Here we studied retrospective data from a total of 19 MPS IIIB patients from Brazil, aiming to evaluate disease progression. Mean age at diagnosis was 7.2 years. Speech delay was one of the first symptoms to be identified, around 2-3 years of age. Behavioral alterations include hyperactivity and aggressiveness, starting around age four. By the end of the first decade, patients lost acquired abilities such as speech and ability to walk. Furthermore, as disease progresses, respiratory, cardiovascular and joint abnormalities were found in more than 50% of the patients, along with organomegaly. Most common cause of death was respiratory problems. The disease progression was characterized in multiple systems, and hopefully these data will help the design of appropriate clinical trials and clinical management guidelines.

Sanfilippo syndrome type B: Analysis of patients diagnosed by the MPS Brazil Network.

Mucopolysaccharidosis type IIIB is a rare autosomal recessive disorder characterized by deficiency of the enzyme N-acetyl-alpha-d-glucosaminidase (NAGLU), caused by biallelic pathogenic variants in the NAGLU gene, which leads to storage of heparan sulfate and a series of clinical consequences which hallmark is neurodegeneration. In this study clinical, epidemiological, and biochemical data were obtained from MPS IIIB patients diagnosed from 2004-2019 by the MPS Brazil Network ("Rede MPS Brasil"), which was created with the goal to provide an easily accessible and comprehensive investigation of all MPS types. One hundred and ten MPS IIIB patients were diagnosed during this period. Mean age at diagnosis was 10.9 years. Patients were from all over Brazil, with a few from abroad, with a possible cluster of MPS IIIB identified in Ecuador. All patients had increased urinary levels of glycosaminoglycans and low NAGLU activity in blood. Main clinical symptoms reported at diagnosis were coarse facies and neurocognitive regression. The most common variant was p.Leu496Pro (30% of alleles). MPS IIIB seems to be relatively frequent in Brazil, but patients are diagnosed later than in other countries, and reasons for that probably include the limited awareness about the disease by health professionals and the difficulties to access diagnostic tests, factors that the MPS Brazil Network is trying to mitigate.

Schizophreniform presentation and abrupt neurologic decline in a patient with late-onset mucopolysaccharidosis type IIIB.

Due to their low frequency and some atypical presentations, inborn errors of metabolism are frequently misdiagnosed or underdiagnosed, which hinders the correct management of these patients. To illustrate that, here we present a patient that, at early school age, had learning disabilities compared to her classmates, especially for writing. She completed basic education in a regular school and was transferred to a secondary school for students with special needs. At 18 years of age, she presented a first psychiatric abrupt outbreak: she spent a month screaming and without sleeping. Behavioral problems then became apparent, especially hyperactivity, destructive and chaotic behavior, anxiety, and auto-aggressivity and hetero-aggressivity. A diagnosis of schizophreniform disorder was established. Clinical genetic evaluation revealed coarse face, macroglossia, coarse thick hair, and mild hepatomegaly, and the hypothesis of mucopolysaccharidosis-III was raised. Laboratory tests indicated high levels of urinary glycosaminoglycans and almost undetectable NAGLU activity, confirming the diagnosis. Sequencing of the NAGLU gene revealed the c.1318G>C (p.Gly440Arg) and c.1834A>G (p.Ser612Gly) mutations.

Demographic, clinical, and ancestry characterization of a large cluster of mucopolysaccharidosis IV A in the Brazilian Northeast region.

Mucopolysaccharidosis (MPS) IVA is a rare autosomal recessive disease with a highly variable distribution worldwide. Discrepancies in the incidence of MPS IVA among populations of different ethnicities are mostly attributed to founder effects. Demographic and clinical data from 28 MPS IVA patients, followed at a single center, and ancestry (Y chromosome and mitochondrial markers) of a subsample of 17 patients, most with the p.Ser341Arg (c.1023C>G) mutation were analyzed. Parental consanguinity was observed in 15/20 couples; a rare homozygous N-acetylgalactosamine-6-sulfatase (GALNS) mutation was found in 7/16 families with intra-familial phenotypic heterogeneity. Paternal ancestry was 94.2% (16/17) European, 5.8% (1/17) African, and 0% Amerindian. The European paternal haplogroups R1a, R1b, and R* accounted for 94.2% (16/17) of the patients. The R1b haplogroup, identified in 59% (10/17) of the patients, is frequently found in populations from the Iberian Peninsula. European, Amerindian, and African maternal ancestry was observed in 46.9% (8/17), 35.4% (6/17), and 17.7% (3/17) of the patients, respectively. Study of a cluster of MPS IVA patients from Northeastern Brazil, with high parental consanguinity and phenotypic heterogeneity showed predominantly European parental ancestry. This ancestry finding corroborates historical data on the local settlement, formed predominantly by European men.