Prevalence of FLG loss-of-function mutations R501X, 2282del4, and R2447X in Spanish children with atopic dermatitis.

BACKGROUND/OBJECTIVES: Atopic dermatitis (AD) is the most prevalent inflammatory skin disorder, and is often associated with a personal or family history of atopic disease. The presence of loss-of-function mutations in the filaggrin gene (FLG) is the main predisposing factor for AD FLG mutations show ethnic and geographical variations, even between European populations. We sought to determine the frequency of the 3 most common FLG null mutations in a population of Spanish children consisting of healthy controls and AD patients. We also investigated the association between these 3 FLG mutations and AD. METHODS: A total of 214 participants (111 AD patients and 103 healthy controls) were enrolled in this study. Genotyping for 3 FLG null mutations (R501X, 2282del4, and R2447X) was performed by conventional Sanger sequencing. RESULTS: The combined mutation frequency was 1.9% in the control group and 12.6% in the AD group. The most common FLG mutation in AD patients was R501X (9.9%), followed by R2447X (2.7%) and 2282del4 (1.8%). CONCLUSION: These findings further our understanding of the prevalence of FLG null mutations in the Spanish population, and suggest that the frequency of FLG mutations in AD patients in Spain is slightly higher than that of other Mediterranean countries.

Association Between VDR and CYP24A1 Polymorphisms, Atopic Dermatitis, and Biochemical Lipid and Vitamin D Profiles in Spanish Population: Case-Control Study.

BACKGROUND: Atopic dermatitis (AD) is the most prevalent inflammatory skin disorder, characterized by impaired epidermal barrier function and an altered immune response, both of which are influenced by vitamin D deficiency. Single-nucleotide polymorphisms (SNPs) in VDR and CYP24A1 have been previously associated with AD. OBJECTIVE: We sought to characterize the associations between the VDR and CYP24A1 polymorphisms and the vitamin D and lipid biochemical profile in children diagnosed with AD. METHODS: A total of 246 participants (143 patients with AD and 103 healthy controls) were enrolled in this study. Genotyping for polymorphisms in VDR (rs2239185, rs1544410, rs7975232, rs2238136, rs3782905, rs2239179, rs1540339, rs2107301, rs2239182, and rs731236) and CYP24A1 (rs2248359 and rs2296241) was performed by allele-specific polymerase chain reaction using integrated fluidic circuit technology. Serum levels of calcium, phosphorus, and vitamin D were measured, and the biochemical lipid profile was determined. RESULTS: Among VDR SNPs, rs2239182 exerted a protective effect against the development of AD, whereas rs2238136 was identified as a risk factor for AD. The GCC haplotype (rs2239185-G, rs1540339-C, and rs2238136-C) appeared to protect against the development of AD. rs2239182-CC was associated with higher 25(OH)D concentrations, whereas rs2238136-TT, rs2239185-GA, and rs2248359-TT were present in a large proportion of patients with serum vitamin D deficiency. rs2239185-AA, rs2239182-CC, and rs1540339-CC were associated with higher serum total cholesterol; rs2239182-TT was associated with lower low-density lipoprotein cholesterol; and rs2239182-TC with lower high-density lipoprotein cholesterol. Both CYP24A1 SNPs (rs2296241-AA and rs2248359-TT) were associated with higher high-density lipoprotein cholesterol levels. CONCLUSIONS: The VDR SNP rs2238136 is a risk factor for AD and other SNPs in VDR and CYP24A1, which may lead to alterations in biochemical parameters that influence the risk of AD. Our findings highlight the complex genetic basis to AD and indicate that interrelationships between different genetic factors can lead to alterations in vitamin D metabolism or lipid profiles, which in turn may influence the development of AD.

A novel pathogenic variant in LCAT causing FLD. A case report.

BACKGROUND: Fish-eye disease (FED) is due to a partial deficiency in LCAT activity. Nevertheless, Familial lecithin-cholesterol acyltransferase deficiency (FLD), also called Norum disease, appears when the deficiency is complete. They are both rare genetic disorders inherited in an autosomal recessive manner. Clinical signs include decreased circulating HDL cholesterol and dense corneal opacity. Kidney injuries also affect patients suffering from FLD. The diagnosis of FLD is based on the presence of characteristic signs and symptoms and confirmed by genetic testing. CASE PRESENTATION: We present a case of a 63-year-old man showing an altered lipid profile with low HDL cholesterol, chronic kidney disease (CKD) and corneal disorders. He was referred to genetic counseling in order to discard genetic LCAT deficiency due to decreased visual acuity caused by corneal opacity. A massive DNA sequencing was conducted using a multigene panel associated with lipid metabolism disturbances. RESULTS AND GENETIC FINDINGS: Two likely pathogenic variants in LCAT were identified and later confirmed by Sanger sequencing. Both (c.491 G > A and c.496 G > A) were missense variants that originated an amino acid substitution (164Arginine for Histidine and 166Alanine for Threonine, respectively) modifying the protein sequence and its 3D structure. CONCLUSIONS: FLD and FED sharing common biochemical features, and the existence of other diseases with similar clinical profiles underline the need for a timely differential diagnosis aiming to address patients to preventive programs and future available therapies. This case, added to the reduced number of publications previously reported regarding FLD and FED, contributes to better understanding the genetic characteristics, clinical features, and diagnosis of these syndromes.