British Journal of Dermatology · 2017 · 16 citations
Natural history and clinical outcome of junctional epidermolysis bullosa generalized intermediate due to a <i>LAMA3</i> mutation
AbstractDear Editor, Junctional epidermolysis bullosa (JEB) comprises rare disorders caused by mutations in genes encoding proteins of the dermoepidermal junction, primarily laminin 332.1 Residual laminin 332 results in intermediate generalized or localized phenotypes, and premature mortality appears to be rather an exception.1 In contrast, a mortality rate of 48% at the age of 15 years was reported,2 and a mean age of death of 6·9 years in 52% of cases,3 but these cohorts were genetically not clearly defined. Here we describe the natural history of JEB in three children with the same LAMA3 splice‐site mutation. In spite of residual laminin 332, two of them died prematurely. Case 1, a girl, and case 2, a boy, were born to healthy, unrelated Jesidian parents, refugees from Iraq. Skin blistering had occurred since birth, predominantly in the main folds (Fig. 1a), and mucosal blistering was reported. Both children were malnourished and in a poor general condition on arrival in Germany. The girl first presented at the age of 6 years. During the 5‐year observation period, she had anaemia and vitamin D deficiency, but developed well, gained weight and showed first signs of puberty at the age of 10 years. Her skin improved, and currently she is doing well. Clinical features of cases 1 and 2 and consequences of the LAMA3 splice‐site mutation c.2008+1G>T. (a) Case 1 (a girl) shows generalized haemorrhagic blistering at 8 years 4 months. Her weight‐for‐age growth chart (according to the World Health Organization 2007) shows regular weight development. At 9 years 3 months, her skin had spontaneously improved. (b) Case 2, the brother of case 1, at 5 years 11 months. The appearance of the skin is similar to that of his sister at a young age. His weight‐for‐age growth chart shows a weight peak between age 7 and 8 years due to steroid overuse. Afterwards, his weight stagnates, and from age 8 years onwards continuous weight loss is seen. At 10 years 2 months, the wound burden has seriously expanded and cachexia is evident. (c) The chronic gluteal wound of case 2. (d) Immunofluorescence staining with antibodies to the laminin α3 chain in control healthy human skin and in cases 1 and 2. Nuclei are stained blue with DAPI (4ʹ,6‐diamidino‐2‐phenylindole). Scale bar = 100 μm. (e) Reverse‐transcriptase polymerase chain reaction (agarose gel shown in the middle panel) and sequencing show the presence of two main transcripts in the control and three transcripts in cases 1 and 2 (C1 and C2), which are schematically represented in the left and right panels. Co, control cDNA from healthy human keratinocytes; M, marker; N, negative control without DNA. GAPDH is shown as a control. Case 2 (Fig. 1b) first presented at the age of 4 years and showed a chronic wound on the buttocks. During follow‐up, this wound never healed, in spite of intensive wound care and plastic surgery (Fig. 1c). The boy displayed vitamin D deficiency and severe microcytic anaemia refractory to oral and intravenous iron and erythropoietin substitution. From the age of 6 years onwards, the boy had repeated episodes of fever. The wound burden increased after the age of 9 years, and he continuously lost weight (Fig. 1b); his general condition deteriorated progressively. High‐caloric drinks were recommended, but were administered only sporadically. A gastrostomy tube to improve feeding and optimize nutrition was declined by the family. At the age of 10 years, the boy developed generalized oedema and exudative enteropathy. Laboratory findings indicated systemic inflammation, severe anaemia, hypoproteinaemia and disturbed coagulation parameters. Due to his poor general condition and clinical suspicion of infection, parenteral antibiotic therapy was administered. Transfusions of erythrocyte, thrombocyte and albumin concentrates were performed repeatedly. By this time, wounds were covering > 70% of the body surface and the skin was extremely fragile. At the age of 10 years and 2 months, our patient developed fever up to 39·0 °C, presumably due to septicaemia originating from a recently installed central venous catheter. Despite escalation of the antibiotic regimen, the boy died of cardiopulmonary failure. Case 3 was a Turkish girl with congenital skin and mucosal blistering and recurrent pyoderma with febrile episodes. From the age of 3 years, she had chronic anaemia treated with transfusions. The girl developed contractures of the large joints and was wheelchair bound at 8 years. She showed failure to thrive, and feeding was performed mostly via a nasogastric tube after the age of 9 years. She had dilative cardiomyopathy with pulmonary oedema (aged 9 years). Her condition progressively deteriorated, she developed diarrhoea and died aged 12 years of multiple organ and congestive heart failure during an infection. At this point, wounds covered 90% of her body surface. In all three cases, immunofluorescence mapping demonstrated similarly reduced immunoreactivity for laminin 332 (Fig. 1d). Mutation analysis disclosed the homozygous LAMA3 mutation c.2008+1G>T, IVS16+1G>T (NM_000227.4), affecting the consensus donor splice site of exon 16, in all cases.4 Total RNA isolated from cultured keratinocytes (RNeasy Kit, Qiagen, Venlo, the Netherlands) was submitted to reverse transcription (Advantage RT‐for‐PCR Kit, Clontech, Mountain View, CA, U.S.A.) and amplified with primers spanning exons 15–19. In controls, the normal transcript (NM_000227.4) and a shorter one lacking exons 16–17 (XM_011525982) were found. In the patients, three transcripts were identified, representing the normal transcript, skipping of exon 16, and skipping of exons 16 and 17 (Fig. 1e). Both shorter transcripts are in frame, leading to laminin α3 chains truncated within the epidermal growth factor‐like domains, which are not functional, and not incorporated in heterotrimers or secreted. Thus, the small amount of laminin 332 observed in the skin of the patients is likely to result from the normally spliced transcript. This seems to be sufficient for wound healing, but insufficient to cope with the wound burden over time. As genetic and epigenetic factors may be modifying,5 we excluded variants in COL17A1 as an explanation for the phenotypic differences in the siblings. Deficient nutrition and chronic inflammation probably aggravate the compromised wound healing, while chronic wounds contribute to iron depletion.6 7 Our report highlights the importance of closely monitored, interdisciplinary care of these patients. The recently reported experimental approach to regenerating the entire epidermis using transgenic stem cells in a similar case with JEB is pioneering,8 but not yet broadly available. A table providing details of the clinical findings of our cases is available from the corresponding author on request. We thank the families and the very dedicated physicians from the department of Pediatrics, Medical Center – University of Freiburg. The technical support by Ioannis Athanasiou, Kaethe Thoma and Annegret Bedorf is gratefully acknowledged. We thank Professor J. Kohlhase for sequencing the DNA samples of cases 1 and 2. Funding sources: A.R. is supported by the Berta‐Ottenstein Programme of the Faculty of Medicine, University of Freiburg. C.H. is supported by Debra International, the Fritz‐Thyssen Foundations and the Deutsche Forschungsgemeinschaft (CRC1140). Conflicts of interest: none to declare.
https://doi.org/10.1111/bjd.16088