Novel and Recurrent PNPLA1 Mutations in Spanish Patients with Autosomal Recessive Congenital Ichthyosis; Evidence of a Founder Effect.

Autosomal recessive congenital ichthyosis (ARCI) is a group of rare non-syndrome diseases that affect cornification. PNPLA1 is one of the 12 related genes identified so far. Mutation screening of this gene has resulted in the identification of 13 individuals, from 10 families, who carried 7 different PNPLA1 mutations. These mutations included 2 missense, 2 frame-shift and 3 nonsense, 3 of them being novel. One of the identified variants, c.417_418delinsTC, was highly prevalent, as it was found in 6 out of 10 (60%) of our ARCI families with PNPLA1 mutations. Clinical manifestations varied significantly among patients, but altered sweating; erythema, palmar hyperlinearity and small whitish scales in flexor-extensor and facial areas were common symptoms. Haplotype analyses of c.417_418delinsTC carriers confirmed the existence of a common ancestor. This study expands the spectrum of the PNPLA1 disease, which causes variants and demonstrates that the c.417_418delinsTC mutation has founder effects in the Spanish population.

Novel CYP4F22 mutations associated with autosomal recessive congenital ichthyosis (ARCI). Study of the CYP4F22 c.1303C>T founder mutation.

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.

Allergic contact dermatitis from EMLA cream in a hemodialyzed patient.

The eutectic mixture EMLA cream has many medical uses, including pain relief for hemodialyzed patients prior to cannulation. Cutaneous side effects associated with its application have rarely been reported. A patient on hemodialysis developed an itchy eruption over his brachial arteriovenous fistula, where he was applying EMLA cream three times per week, prior to puncture for hemodialysis. Patch testing elicited a positive reaction to several allergens, including EMLA cream "as is" and prilocaine. The lesions resolved after topical treatment with corticosteroids.