Genetic spectrum of Brazilian suspected Bartter Syndrome Patients [post]

Ana Carola Hebbia Lobo Messa, Juliana Caires de Oliveira Achili Ferreira, Fernanda Fonseca, Andreia Rangel-Santos, Maria Helena Vaisbich
2020 unpublished
Background This paper's goal is to show the genetic study results of suspected Bartter syndrome (BS) patients followed in a pediatric nephrology reference center in Sao Paulo/Brazil, verify a possible genotype-phenotype correlation and compare the genetic results with those from other regions of the globe. Results This descriptive study included 22 patients (21 families) with clinical diagnosis of BS. Pathogenic variants in BS-related genes were detected in 19/22 patients. No BS-related genes
more » ... BS-related genes were detected in three patients (one case of Congenital Chloride Diarrhea and two siblings with clinical Antenal BS that, in fact, had Gitelman Syndrome). We observed that 16/19 BS-confirmed patients had CLCNKB mutations (BS type 3) with a large phenotypical diversity. Among them, the deletion of the entire gene (del 1–20) was the most frequent variant detected. Interestingly, we observed that patients with homozygous or heterozygous del 1–20 presented earlier manifestations than patients with other CLCNKB mutations. They presented no other clinical significant difference. Conclusion This study demonstrates the importance of an appropriate investigation of clinically suspected BS patients to rule out pseudo-BS. This data also confirms the difficult to differentiate these patients based just on clinical findings, similar to what has been reported in other studies. There were patients with clinical Antenatal BS in whom the genetic analysis confirmed the final diagnosis of GS or BS type 3. Among BS cases, BS type 3 was the most frequent in this Brazilian cohort and del 1–20 was the most frequently variant detected. In addition, BS type 3 patients with homozygous or heterozygous del 1–20 had earlier manifestations than patients with other CLCNKB mutations. Brazilian community has a particular characteristic miscegenation as well as different origins such as Europeans, Africans and Asians and comparing our results with those from other regions we can suppose the genetic background of this Brazilian cohort is related to African and Portuguese inheritance, probably originated in the early period of immigration (colonization and slavery period). Limitations: low number of patients from a single center. However, as a rare disease all data can contribute to the improvement for diagnosis and treatment.
doi:10.21203/rs.3.rs-35560/v1 fatcat:duyuwdmqrjc4tb3furpdivvjxi