Targeted next-generation sequencing identifies a novel mutation of LAMB3 in a Chinese neonatal patient presented with junctional epidermolysis bullosa.

RATIONALE: Epidermolysis bullosa (EB) refers to a group of rare inherited mechanobullous disorders that present with great clinical and genetic heterogeneity. Its severity ranges from mild blistering to life-threatening. However, the clinical symptoms of different types of EB overlap significantly, especially at an early stage. Thus it is important to clarify the diagnosis for prognostic implications, patient management, and genetic counseling. PATIENT CONCERNS: Here, we report a 10-day-old male neonate from a nonconsanguineous Chinese family. He showed a bulla on the left lower limb lasting for 3 days, erosions around fingertips and toe tips at birth (predominantly on fingers), with the progressive spread of generalized blisters over the body as well as the development of the illness. DIAGNOSIS: The patient was diagnosed with suspected epidermolysis bullosa according to the blisters and erosions of the body as well as the pyogenic fingernails and toenails. INTERVENTIONS: The patient was performed targeted next-generation sequencing (NGS) with 9 candidate known genes, subsequently, his parents were screened for the mutations identified in the patient by Sanger sequencing. Then, prenatal diagnosis with amniotic fluid was performed in the subsequent pregnancy by Sanger sequencing. OUTCOMES: Targeted NGS revealed a previously unreported splice site variant c.822+1G>A (IVS 8) and a known recurrent nonsense variant c.124C>T (p.Arg42Ter, exon 3) in LAMB3 gene. The patient's father possessed a heterozygous c.822+1G>A mutation, his mother possessed a heterozygous c.124C>T mutation. For the subsequent pregnancy, the analyses of amniotic fluid sample indicated that the fetus carried neither of the mutations. LESSONS: Our finding will further enlarge LAMB3 genotype-phenotype correlations spectrum. Targeted capture sequencing is a valuable method to illustrate precise molecular pathology in patients with EB disorders, especially at an early stage of the clinical evaluation of complex disorders to avoid unnecessary and economically wasteful tests.