Mucopolysaccharidosis VII in Brazil: natural history and clinical findings.

BACKGROUND: Mucopolysaccharidosis type VII (MPS VII), also known as Sly syndrome, caused by deficiency of the lysosomal enzyme ß-glucuronidase, is an ultra-rare disorder with scarce epidemiological data and few publications about natural history and clinical spectrum. METHODS: We conducted a case series report which included retrospective data from all MPS VII patients diagnosed through the "MPS Brazil Network" who were known to be alive in 2020 in Brazil (N = 13). Clinical data were obtained from a review of the medical records and descriptive statistics and variables were summarized using counts and percentages of the total population. RESULTS: The majority of the patients were from the Northeast region of Brazil. Among the signs and symptoms that raised the clinical suspicion of MPS, coarse face was the most frequent; 58% of the patients had a history of non-immune hydrops fetalis. All the subjects presented short neck and trunk. The majority presented typical phenotypical signs of MPS disorders. They all presented neurodevelopmental delay and cognitive impairment. About half of this cohort had knees deformities. Dysostosis multiplex was identified in almost all patients and cardiomyopathy was less frequent than observed in other types of MPSs. The mean age at diagnosis was 5 years, ranging from 1 to 14 years. Almost all patients (12/13) were homozygous for the c.526C>T (p.Leu176Phe) mutation. A novel variant of the GUSB gene was found, the c.875T>C (p.Leu292Pro), in a compound heterozygous with the c.526C>T (p.Leu176Phe) variant. CONCLUSIONS: This case series is the biggest data collection of MPS VII patients alive in Latin America. The overall clinical picture of the MPS VII patients is very similar to other MPS disorders, including a spectrum of severity and delayed diagnosis.

Phenylketonuria Diagnosis by Massive Parallel Sequencing and Genotype-Phenotype Association in Brazilian Patients.

Phenylketonuria (PKU) is a common inborn error of amino acid metabolism in which the enzyme phenylalanine hydroxylase, which converts phenylalanine to tyrosine, is functionally impaired due to pathogenic variants in the PAH gene. Thirty-four Brazilian patients with a biochemical diagnosis of PKU, from 33 unrelated families, were analyzed through next-generation sequencing in the Ion Torrent PGM™ platform. Phenotype-genotype correlations were made based on the BioPKU database. Three patients required additional Sanger sequencing analyses. Twenty-six different pathogenic variants were identified. The most frequent variants were c.1315+1G>A (n = 8/66), c.473G>A (n = 6/66), and c.1162G>A (n = 6/66). One novel variant, c.524C>G (p.Pro175Arg), was found in one allele and was predicted as likely pathogenic by the American College of Medical Genetics and Genomics (ACMG) criteria. The molecular modeling of p.Pro175Arg indicated that this substitution can affect monomers binding in the PAH tetramer, which could lead to a change in the stability and activity of this enzyme. Next-generation sequencing was a fast and effective method for diagnosing PKU and is useful for patient phenotype prediction and genetic counseling.

Mucopolysaccharidosis VI and effects on growth of the apical bases: a case report.

OBJECTIVE: Mucopolysaccharidosis (MPS) VI is a rare disorder caused by an autosomal recessive mutation in the short arm of chromosome 5 (5q12-13) leading to an N-acetylgalactosamine-sulfatase lysosomal enzyme deficiency and numerous systemic clinical changes. The oral and maxillofacial complex may exhibit tooth eruption anomalies, macroglossia, gingival hypertrophy, mouth breathing, increased lower facial height, open bite, retrognathia, and progressive TMJ arthrosis. This report describes craniofacial growth changes in two MPS VI patients, sisters and daughters of outbred parents, who were longitudinally monitored from 11 to 15 years of age. STUDY DESIGN: Skull lateral teleradiography and cephalometric tracings were performed. The measurements were assessed in the anteroposterior and vertical directions based on protocols by McNamara and Usp/Unicamp and compared to the normal reported ranges. RESULTS: A similar skeletal class III malocclusion was observed in both patients. The jaw was retruded, the anterior skull base decreased, and the mandibular body was normal or larger than normal. The vertical growth direction differed between the patients; one was hyperdivergent, while the other was hypodivergent. CONCLUSIONS: By understanding the craniofacial growth changes in MPS VI patients, new treatment options may be developed for affected patients.

Evaluation of the tshr gene reveals polymorphisms associated with typical symptoms in primary congenital hypothyroidism.

Primary congenital hypothyroidism (PCH) has an incidence of approximately 1 in each 3000-4000 live births. In the last two decades, nearly 50 types of the distinct inactivating mutations have already been described in the coding region of the tshr gene. The aim of present study was to investigate tshr gene mutations in patients with primary congenital hypothyroidism, analyzing a sample of 106 patients that were diagnosed with PCH. Genomic DNA was isolated from peripheral blood samples, and 10 exons from the TSH receptor were automatically sequenced. Five nucleotide alterations (P52T, N187N, A459A, L645L, and D727E. N187N and D727E polymorphisms) were associated with positive medical history. In view of the clinical, biochemical and molecular heterogeneity of the etiology of the PCH, the study of polymorphisms is critical for investigating the possible associations with prevailing symptoms of this disorder.

Visual Dysfunction of Type I and VI Mucopolysaccharidosis Patients Evaluated with Visual Evoked Cortical Potential.

PURPOSE: To evaluate the visual system of patients suffering from type I or VI mucopolysaccharidosis (MPS) by recording the visual evoked cortical potential (VECP). METHODS: Two patients with MPS VI and 2 patients with MPS I were tested before and after enzyme replacement therapy (ERT). A control group of 20 subjects was tested for statistical comparison. VECP was elicited by monocular stimulation with 1-Hz phase-reversal checkerboard patterns at 0.5 and 2 cycles per degree and with 16° of visual field. In all patients, both eyes were tested. VECP amplitude and latency were measured and compared with tolerance limits obtained from controls. RESULTS: MPS I and VI patients have a severe visual impairment that can be quantified by measuring VECPs. Even after several weeks of ERT, the visual impairment remained unaltered, indicating that the treatment had no significant influence on the visual conditions of MPS patients. Visual responses to high spatial frequencies were more deeply impaired than responses to low spatial frequencies. This can be explained by the kind of damage in the visual system that preferentially targets the eye optics. CONCLUSION: VECPs can be used to monitor the degree of visual impairment of MPS patients and to check ERT efficacy.

Mucopolysaccharidosis I, II, and VI: Brief review and guidelines for treatment.

Mucopolysaccharidoses (MPS) are rare genetic diseases caused by the deficiency of one of the lysosomal enzymes involved in the glycosaminoglycan (GAG) breakdown pathway. This metabolic block leads to the accumulation of GAG in various organs and tissues of the affected patients, resulting in a multisystemic clinical picture, sometimes including cognitive impairment. Until the beginning of the XXI century, treatment was mainly supportive. Bone marrow transplantation improved the natural course of the disease in some types of MPS, but the morbidity and mortality restricted its use to selected cases. The identification of the genes involved, the new molecular biology tools and the availability of animal models made it possible to develop specific enzyme replacement therapies (ERT) for these diseases. At present, a great number of Brazilian medical centers from all regions of the country have experience with ERT for MPS I, II, and VI, acquired not only through patient treatment but also in clinical trials. Taking the three types of MPS together, over 200 patients have been treated with ERT in our country. This document summarizes the experience of the professionals involved, along with the data available in the international literature, bringing together and harmonizing the information available on the management of these severe and progressive diseases, thus disclosing new prospects for Brazilian patients affected by these conditions.