PMC9561087_01
(A-C) Blisters and scarring on the knees, feet, and fingers, respectively. (D) Retrograde urethrography showed stricture at the cavernous part of urethra and inflated bulbar urethra.
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F1
Various degrees of scarring and hyperpigmentation were found on the corners of the patient's mouth, as well as on his fingers, feet, and extremities, especially the knees (Figures 1A-C). Stricture at the cavernous urethra (~8.5 cm long) and an inflated bulbar urethra were found (Figure 1D).
(A) Exome sequencing identified a homozygous mutation, LAMB3: NM_000228.2: exon11: c.1172_1179delinsTGTGTGTGCAAGGAG: p.P391Lfs*23 in the patient. (B) Pedigree showing unaffected parents and two affected brothers. (C) Homozygosity of this mutation in the patient and his older brother was confirmed by Sanger sequencing, and the clinically unaffected parents were heterozygous carriers.
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F2
Furthermore, the clinically unaffected parents were heterozygous carriers of the corresponding mutation (Figure 2C), indicating a recessive genetic disease (Figure 2B). TGTGTGTGCAAGGAG was inserted in this position, which led to a transition from proline to leucine on the 391st amino acid, resulting in a frameshift and truncated protein (Figure 2A). This mutation is a novel variant of LAMB3-associated JEB that has not been reported in the OMIM and gnomAD databases.
(A) Extraction of tongue mucosa. (B) The mucosa graft was sutured to the urinary tract.
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F3
Lingual mucosal urethroplasty was performed under general anesthesia (Figures 3A,B).