Answer of Dermatopathology Case 54

Ichthyosis Vulgaris


Abstract:

Clinical features of the nephrotic syndrome associated with ichthyosis vulgaris and analysis of related gene mutation.Zhonghua Er Ke Za Zhi.2010;48(1):44-9.
OBJECTIVE: To study clinical features of 3 children who presented with nephrotic syndrome (NS) associated with ichthyosis vulgaris (IV), and to detect relationship between NS associated with IV in patients and FLG gene or NPHS2 gene. METHOD: Clinical and kidney pathological data of the 3 patients were analyzed and progress of pathologic damage in the patient kidney was observed through repeated percutaneous renal biopsy. Using polymerase chain reaction-single strand conformation polymorphism and DNA sequencing, the diversity of the expression of NPHS2 gene in the 3 patients were analyzed, and FLG gene in the 3 patients and parts of their family members with IV was detected. RESULT: (1) The age of the 3 patients (patient 1 was a girl and patients 2 and 3 were boys) suffering from NS was 3 years and 8 months, 2 years and 6 months, and 5 years and 3 months, respectively. The age of onset of IV was 1 year and 6 months, 10 months, and 2 years and 6 months, respectively. All the 3 patients were resistant to steroid therapy. Despite multi-immunosuppressive therapy, no clinical response was achieved. The patients were followed up for 1.5 to 4.0 years. The patients displayed continuous proteinuria, renal function was normal, but their heights were lower than other children at the same age. (2) The older brother of patient 1 died of uremia. The other patients' family members did not have kidney disease. (3) Renal histopathology showed that the patients 1 and 2 had mild mesangial proliferative glomerulonephritis (MsPGN) and the patient 3 had minimal change disease (MCD). One and a half years after the first renal biopsy, the patients 1 and 2 underwent repeated renal biopsy. Renal histopathology showed that the 2 patients' disease developed to medium MsPGN. (4) None of the 3 patients had NPHS2 gene mutation. All the three patients had R501X and 2282del4 which are the common gene mutation type of the FLG, and all the patients were heterozygote. With the detection of the FLG gene of the part of the patients of the three families, the second patient's grandfather had the R501X homozygote mutation and the others were the R501X heterozygote mutation and 2282del4 heterozygote mutation. CONCLUSION: The 3 cases of NS associated with IV had no response to steroid and multi-immunosuppressive therapy, the renal damage observed by histopathology progressed fast. The children with NS associated with IV displayed R501X heterozygote mutation and 2282del4 heterozygote mutation of FLG gene, which suggested that the absence of response to steroid and multi-immunosuppressive therapy may be related to the FLG gene.

Novel and recurrent mutations in the filaggrin gene in Chinese patients with ichthyosis vulgaris.Br J Dermatol.2010 Jul;163(1):63-9. Epub 2010 Mar 19.
BACKGROUND: Ichthyosis vulgaris (IV) is a common inherited skin disorder, and the filament aggregating protein (filaggrin) is a key protein involved in skin barrier function. Mutations in the filaggrin gene (FLG) have recently been identified as the cause of IV. However, there have been no reports of FLG mutations in mainland Chinese families with IV. OBJECTIVES: To identify FLG mutations in Chinese patients with IV. METHODS: Eleven unrelated Chinese families with IV were examined for FLG mutations with denaturing high-performance liquid chromatography prescreening and sequencing. SNaPShot was employed to obtain a high-throughput screening for the identified mutations. RESULTS: Three mutations - one novel mutation (Q1256X) and two known mutations (3321delA and E2422X) - were identified in these families. The novel mutation, Q1256X, found in a Chinese family with IV, was located in filaggrin repeat 3. Mutation 3321delA, previously found in Japanese patients, was present in eight Chinese families with IV. Mutation E2422X, previously found in a Dutch patient of Chinese origin, was present in two Chinese families with IV. Neither of the null mutations, Q1256X and E2422X, were found in 100 unrelated control cases from the Chinese population; however, the mutation ratio for 3321delA was 3% in these controls. CONCLUSIONS: Our study suggests that each population may have a unique and prevalent set of FLG mutations.

FLG mutations in ichthyosis vulgaris and atopic eczema: spectrum of mutations and population genetics.Br J Dermatol.2010 Mar;162(3):472-7. Epub 2009 Dec 2.
Filaggrin is a key protein involved in skin barrier function. Mutations in the gene encoding filaggrin (FLG) have been identified as the cause of ichthyosis vulgaris and have been shown to be major predisposing factors for atopic eczema (AE), initially in European populations. Subsequently, FLG mutations were identified in Japanese, Chinese, Taiwanese and Korean populations. It was demonstrated that FLG mutations are closely associated with AE in the Japanese population. Notably, the same FLG mutations identified in the European population were rarely found in Asians. These results exemplify differences in filaggrin population genetics between Europe and Asia. For mutation screening, background information needs to be obtained on prevalent FLG mutations for each geographical population. It is therefore important to establish the global population genetics maps for FLG mutations. Mutations at any site within FLG, even mutations in C-terminal imperfect filaggrin repeats, cause significant reductions in amounts of profilaggrin/filaggrin peptide in patient epidermis as the C-terminal region is essential for proper processing of profilaggrin into filaggrin. Thus, no genotype-phenotype correlation has been observed in patients with FLG mutations. A restoration of the barrier function seems a feasible and promising strategy for treatment and prevention in individuals with filaggrin deficiency.