Updated birth prevalence and relative frequency of mucopolysaccharidoses across Brazilian regions.

The mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by 11 enzyme deficiencies, classified into seven types. Data on the birth prevalence of each MPS type are available for only a few countries, and the totality of cases may be underestimated. To determine the epidemiological profile of MPS in each Brazilian region, we analyzed data collected between 1982 and 2019 by a national reference laboratory and identified 1,652 patients. Using data between 1994 and 2018, the birth prevalence (by 100,000 live births) for MPS was 1.57. MPS II was the most common type of MPS in Brazil, and its birth prevalence was 0.48 (0.94 considering only male births). Regarding the number of cases per region, MPS II was the most frequent in the North and Center-West (followed by MPS VI), and also in the Southeast (followed by MPS I); MPS I and MPS II were the most common types in the South; and MPS VI was the most common in the Northeast (followed by MPS II). The differences observed in the relative frequencies of MPS types across Brazilian regions are likely linked to founder effect, endogamy, and consanguinity, but other factors may be present and need further investigation.

Transferrin isoelectric focusing for the investigation of congenital disorders of glycosylation: analysis of a ten-year experience in a Brazilian center / Isoeletrofocalização da transferrina para investigação das doenças congênitasda glicosilação: análise de dez anos de experiência de um centro brasileiro

Abstract Objectives: To characterize cases of suspected congenital disorders of glycosylation (CDG) investigated in a laboratory in southern Brazil using the transferrin isoelectric focusing TfIEF test from 2008 to 2017. Method: Observational, cross-sectional, retrospective study. The laboratory records of 1,546 individuals (median age = 36 months, 25-75 IQR = 10-108; males = 810) submitted to the TfIEF test during the period were reviewed. Results: Fifty-one individuals (3%) had an altered TfIEF pattern (5 ± 2.8 cases/year; median age = 24 months, 25-75 IQR = 11-57 months; males = 27, 53%). For 14 of them, data on diagnosis conclusion were available (classic galactosemia = 4; hereditary fructose intolerance = 4; peroxisomal diseases = 2; PMM2-CDG = 2; MPDU1-CDG = 1; SLC35A2-CDG = 1).Comparing the cases with the normal and altered TfIEF patterns, there was a higher prevalence of altered cases in the age group from 11 months to 3 years. There was an increase in the likelihood of change in TfIEF, especially in the presence of inverted nipples or liver disease. Conclusions: The data suggest that the investigation of a case with suspected CDG is a complex problem, being aggravated by the existence of other IEMs (inborn errors of metabolism) associated with altered TfIEF pattern and lack of access to confirmatory tests. The presence of inverted nipples and liver disease, especially in individuals aged 11 months to 3 years, should suggest the need for TfIEF investigation.

Resumo Objetivos: Caracterizar os casos com suspeita de CDG investigados em laboratório do sul do Brasil pelo exame de IEFTF de 2008 a 2017. Metodologia: Estudo observacional, transversal, retrospectivo. Foram revisadas as fichas laboratoriais de 1.546 indivíduos (mediana de idade = 36 meses, IQ 25-75 = 10-108; sexo masculino = 810) que fizeram o exame de IEFTF no período. Resultados: Cinquenta e um indivíduos (3%) apresentaram padrão alterado na IEFTF (5 ± 2,8 casos/ano; mediana de idade = 24 meses, IQ 25-75 = 11-57 meses; sexo masculino = 27, 53%). Para 14 deles, estavam disponíveis dados sobre a conclusão do diagnóstico (galactosemia clássica = 4; intolerância hereditária à frutose = 4; doenças peroxissomais = 2; PMM2-CDG = 2; MPDU1-CDG = 1; SLC35A2-CDG = 1). Comparando os casos com padrão normal e alterado na IEFTF, houve maior prevalência de casos alterados na faixa etária de 11 meses a 3 anos. Verificou-se um aumento na probabilidade de alteração na IEFTF principalmente na presença de mamilos invertidos ou de hepatopatia. Conclusões: Os nossos dados sugerem que a investigação de um caso com suspeita de CDG é complexa, é agravada pela existência de outros EIM associados a padrão alterado na IEFTF e pela falta de acesso a exames confirmatórios. A presença principalmente de mamilos invertidos e de hepatopatia em indivíduos na faixa etária de 11 meses a 3 anos deve sugerir a necessidade de investigação por IEFTF.

Transferrin isoelectric focusing for the investigation of congenital disorders of glycosylation: analysis of a ten-year experience in a Brazilian center.

OBJECTIVES: To characterize cases of suspected congenital disorders of glycosylation (CDG) investigated in a laboratory in southern Brazil using the transferrin isoelectric focusing TfIEF test from 2008 to 2017. METHOD: Observational, cross-sectional, retrospective study. The laboratory records of 1,546 individuals (median age=36 months, 25-75 IQR=10-108; males=810) submitted to the TfIEF test during the period were reviewed. RESULTS: Fifty-one individuals (3%) had an altered TfIEF pattern (5±2.8 cases/year; median age=24 months, 25-75 IQR=11-57 months; males=27, 53%). For 14 of them, data on diagnosis conclusion were available (classic galactosemia=4; hereditary fructose intolerance=4; peroxisomal diseases=2; PMM2-CDG=2; MPDU1-CDG=1; SLC35A2-CDG=1).Comparing the cases with the normal and altered TfIEF patterns, there was a higher prevalence of altered cases in the age group from 11 months to 3 years. There was an increase in the likelihood of change in TfIEF, especially in the presence of inverted nipples or liver disease. CONCLUSIONS: The data suggest that the investigation of a case with suspected CDG is a complex problem, being aggravated by the existence of other IEMs (inborn errors of metabolism) associated with altered TfIEF pattern and lack of access to confirmatory tests. The presence of inverted nipples and liver disease, especially in individuals aged 11 months to 3 years, should suggest the need for TfIEF investigation.