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Mutations in CYP4F22 cause autosomal recessive congenital ichthyosis (ARCI). However, less than 10% of all ARCI patients carry a mutation in CYP4F22. In order to identify the molecular basis of ARCI among our patients (a cohort of ninety-two Spanish individuals) we performed a mutational analysis using direct Sanger sequencing in combination with a multigene targeted NGS panel. From these, eight ARCI families (three of them with Moroccan origin) were found to carry five different CYP4F22 mutations, of which two were novel. Computational analysis showed that the mutations found were present in highly conserved residues of the protein and may affect its structure and function. Seven of the eight families were carriers of a highly recurrent CYP4F22 variant, c.1303C>T; p.(His435Tyr). A 12Mb haplotype was reconstructed in all c.1303C>T carriers by genotyping ten microsatellite markers flanking the CYP4F22 gene. A prevalent 2.52Mb haplotype was observed among Spanish carrier patients suggesting a recent common ancestor. A smaller core haplotype of 1.2Mb was shared by Spanish and Moroccan families. Different approaches were applied to estimate the time to the most recent common ancestor (TMRCA) of carrier patients with Spanish origin. The age of the mutation was calculated by using DMLE and BDMC2. The algorithms estimated that the c.1303C>T variant arose approximately 2925 to 4925 years ago, while Spanish carrier families derived from a common ancestor who lived in the XIII century. The present study reports five CYP4F22 mutations, two of them novel, increasing the number of CYP4F22 mutations currently listed. Additionally, our results suggest that the recurrent c.1303C>T change has a founder effect in Spanish population and c.1303C>T carrier families originated from a single ancestor with probable African ancestry.

To investigate the involvement of the CIAS1/PYPAF1/NALP3 gene in 7 unrelated Spanish families with recurrent autoinflammatory diseases characterized by early onset, recurrent fever, and a chronic urticarial rash, in whom a clinical diagnosis of cryopyrin‐associated periodic syndromes (CAPS) is suspected. Clinical symptoms, results of laboratory analyses, and data on previous treatments in members of the 7 families were recorded on a questionnaire specific for hereditary autoinflammatory diseases. All coding regions and intronic flanking boundaries of the CIAS1/PYPAF1/NALP3 gene were amplified by polymerase chain reaction and sequenced. Five different missense mutations, including 2 de novo and 1 previously unreported mutation (R488K), were identified in exon 3 of the CIAS1/PYPAF1/NALP3 gene in 5 of the 7 affected families. Expanded genetic analysis among the healthy individuals identified incomplete penetrance in 2 families. No mutations were found in 2 of the 3 patients with chronic infantile neurologic, cutaneous, articular (CINCA) syndrome/neonatal‐onset multisystem inflammatory disease (NOMID).The clinical data suggested a diagnosis of familial cold‐induced autoinflammatory syndrome in 3 families, CINCA/NOMID syndrome in 3 others, and a possible Muckle‐Wells syndrome, whereas mutational analysis showed different CIAS1/PYPAF1/NALP3 missense mutations in 5 families. These data are consistent with a common molecular basis of these diseases and highlights the phenotypic heterogeneity among CIAS1/PYPAF1/NALP3 gene–associated syndromes. The previously unreported mutation and the incomplete penetrance found in 2 families expand the genetic basis underlying these autoinflammatory syndromes. These findings should alert clinicians to the possible genetic basis of these conditions, even in the absence of a family history, in their attempts to establish an accurate diagnosis and the optimal therapeutic approach. [ABSTRACT FROM AUTHOR]