Immunofluorescence mapping in inherited epidermolysis bullosa: a study of 86 cases from India.

BACKGROUND: Epidermolysis bullosa (EB) poses diagnostic challenges in infancy. In India, the diagnosis is largely clinical. There were no facilities to perform immunofluorescence mapping (IFM) until recently, and electron microscopy, which requires expertise to interpret, is limited to a few research laboratories. OBJECTIVES: To describe the patterns of IFM staining in the various forms of EB in Indian patients and to correlate these findings with clinical diagnosis. METHODS: We conducted a cross-sectional study of IFM findings in EB. Antibodies against type IV collagen, cytokeratin 14, laminin 332 and type VII collagen were used. Clinical correlation was performed in all cases, and concordance-discordance rates were calculated. RESULTS: Eighty-six patients with a diagnosis of EB were included in the study. There were 29 with EB simplex (EBS), 18 with junctional EB (JEB) and 15 with dystrophic EB (DEB). The remaining 24 cases included rare variants, cases with overlapping clinical features and cases where the type of EB was not known. On IFM diagnosis, there were 32 cases of EBS, 15 JEB, 17 DEB and two Kindler syndrome. Two cases were not EB and 18 were inconclusive. IFM could establish the type in 12 of 15 cases (80%) that had overlapping clinical features. Most of these cases were under 1 year of age. Overall the concordance was 57% and was seen best in cases of EBS. CONCLUSIONS: This is the first large study of IFM of the subtypes of EB in Indian patients. The study provides a framework for better understanding of EB in Indian patients and for better diagnosis and management, particularly in infancy.

Clinical heterogeneity in recessive epidermolysis bullosa due to mutations in the keratin 14 gene, KRT14.

BACKGROUND: Epidermolysis bullosa simplex (EBS), the most common subtype of EB, is usually inherited as an autosomal dominant trait caused by mutations in either the keratin 5 (KRT5) or keratin 14 (KRT14) genes. Recessive EBS (R-EBS) is extremely rare. METHODS: We present the first Australian patient diagnosed with R-EBS, to our knowledge, and a comprehensive review of genotypes and phenotypes of R-EBS reported cases. RESULTS: The female proband, of Turkish descent with consanguineous parentage, was referred to us at the age of 8 years. Clinically, she had a severe phenotype including generalized blisters, mucosal involvement and EB naevi. Immunofluorescence mapping and electron microscopy were consistent with a diagnosis of EBS. Staining for Keratin 14 (K14) was negative. The basal layer, however, reacted with monoclonal antibodies to keratins 6 (K6) and 16 (K16). Mutation screening from genomic DNA showed that the proband was homozygous for the truncation mutation Y204X in exon 3 of KRT14, and both unaffected parents were heterozygous for a single KRT14 Y204X mutation. The phenotype of our patient is reported in more detail and with longer follow-up than those of others published in the literature. DISCUSSION: The proband's phenotype was severe as an infant but improved with age, suggesting that an alternative keratin is pairing with K5 in her skin to compensate for the loss of K14--a novel biological compensatory mechanism. It is interesting that K6 and K16 were expressed, as these are normally positive in hyperproliferative skin disorders.