Identification of a homozygous one-basepair deletion in exon 14 of the LAMB3 gene in a patient with Herlitz junctional epidermolysis bullosa and prenatal diagnosis in a family at risk for recurrence.
The combination of a nonsense and a missense mutation in the LAMB3 gene appears to be important in determining the milder clinical phenotype in some cases of the nonlethal forms of junctional epidermolysis bullosa involving abnormalities in laminin 5.
The combination of nonsense and a missense mutation in the LAMB3 gene appears to be important in determining the milder clinical phenotype in some cases of the nonlethal forms of junctional epidermolysis bullosa involving abnormalities in laminin 5.
Laminin 5, an anchoring filament attachment protein within the lamina lucida of the basement membrane zone involved in the pathogenesis of junctional epidermolysis bullosa (JEB), consists of three polypeptide subunits, the alpha 3, beta 3, and gamma 2 chains which are encoded by the LAMA3, LAMB3, and LAMC2 genes, respectively.
Recently, one particular mutation, R635X in the LAMB3 gene, has been found to account for approximately 40% of all JEB laminin 5 mutations (Kivirikko et al., Hum Mol Genet 1996; 5: 231-7).
Predominance of the recurrent mutation R635X in the LAMB3 gene in European patients with Herlitz junctional epidermolysis bullosa has implications for mutation detection strategy.
Mutations in the genes (LAMA3, LAMB3, and LAMC2) encoding the subunit polypeptides of the cutaneous basement membrane zone protein laminin 5 have been reported in different forms of junctional epidermolysis bullosa (JEB), an inherited blistering skin disease.
In this study, we performed genetic analyses in two unrelated Japanese families with Herlitz junctional epidermolysis bullosa and identified two novel nonsense mutations in the LAMB3 gene.
As the third patient is a young child with fewer features of this subtype to date, identification of E210K in combination with a nonsense LAMB3 mutation may be predictive of the subsequent development of a generalized atrophic benign EB phenotype both in this child and in other junctional EB patients with the E210K mutation.
These results suggest that Herlitz junctional epidermolysis bullosa in this patient developed as a result of reduction to homozygosity of the maternal LAMB3 mutation on chromosome 1q32.
This report documents compound heterozygosity for novel mutations in LAMB3 of a Japanese patient showing typical clinical features of generalized atrophic benign epidermolysis bullosa.
In this study, we examined the LAMB3 gene for mutations in 22 Herlitz junctional epidermolysis bullosa families, and identified 15 distinct mutations, eight of them previously unreported, bringing the total number of distinct Herlitz junctional epidermolysis bullosa mutations in LAMB3 to 35.
Markedly reduced staining for laminin 5 indicated the Herlitz type of JEB (OMIM 226700), which could be confirmed by mutation analysis in the LAMB3 gene, showing homozygous nonsense mutations.