Phenotype and genotype correlation of inherited epidermolysis bullosa in Indonesia

Background: Inherited epidermolysis bullosa (EB) is a group of genodermatoses with considerable clinical and genetic heterogeneity. Clinical diagnosis of the EB subtypes is frequently imprecise and requires confirmation with genetic testing. There is still limited study using genetic testing to identify EB subtypes in Indonesia. This study aims to identify the pathogenic variants of inherited EB patients at the Department of Dermatology and Venereology, Universitas Padjadjaran-Dr Hasan Sadikin General Hospital in Bandung, West Java, Indonesia and to describe the correlation between the phenotype and genotype of our patients.

Methods: Twelve patients clinically diagnosed with EB were included in this study. Genetic testing was performed in collaboration with KK Women's and Children's Hospital, Singapore.

Results: Pathogenic variants were identified in the COL7A1 gene in seven patients, namely Dominant Dystrophic EB (DDEB) with mutation types c.5945G>T, c.6218G>A, Recessive Dystrophic EB (RDEB) c.2005C>T, c.6081dup, c.1268C>T, c.1784C>T which are all known mutations. Novel mutations were found in the COL7A1 gene in two patients namely DDEB c.6253G>T and RDEB c.6740C>T. Two EB Simplex (EBS) patients showed mutation KRT14 gene as c.356T>C, c.373C>T which are known mutation. In addition, a novel mutation in LAMA3 gene c.2649del was found in one Junctional EB (JEB) patient.

Conclusion: The molecular diagnoses of 12 Indonesian EB patients were identified, of which three were novel pathogenic variants. Concordance between the initial clinical diagnosis and genetic testing was only 33%. This demonstrated the importance of early genetic testing for accurate diagnosis, prognostication, management and genetic counselling.