Non-invasive analysis of skin mechanical properties in patients with lamellar ichthyosis.

BACKGROUND: Reliable methods for the quantitative evaluation of skin of patients with ichthyosis are critically needed. Our purpose was to evaluate the biomechanical parameters of skin in a cohort of patients with clinically diagnosed lamellar ichthyosis. MATERIALS AND METHODS: Twenty-two patients diagnosed with lamellar ichthyosis were studied. Ichthyosis plaques located in upper distal limbs were assayed, and a nearby anatomical region without plaques from the same patient was employed as control. Skin biomechanical properties were studied through a non-invasive device (Cutometer® MPA 580). RESULTS: Ichthyosis plaques had higher values for the Uf-Ua parameter and lower values for the Ua/Uf, Ur/Ue, and Ur/Uf parameters. Adults and children showed similar statistical differences. There were no significant differences in data from men, whereas in women differences for all of the parameters were found. There was a significant decrease in the hydration and an increase in melanin index in the ichthyosis plaques. CONCLUSION: Our results suggest that analysis of parameters Uf-Ua, Ua/Uf, Ur/Ue, Ur/Uf, hydration, and melanin index could be employed for quantitative monitoring of skin. Therefore, the non-invasive method applied may be suitable for evaluation of skin of patients with ichthyosis in response to medical treatments.

High prevalence of autosomal recessive congenital ichthyosis in a Mexican population caused by a new mutation in the TGM1 gene: epidemiological evidence of a founder effect.

BACKGROUND: Autosomal recessive congenital ichthyoses (ARCI) are inherited disorders produced by mutations in essential genes for the skin function. A low prevalence of this disease has been resported worldwide; however, in a recent study, we identified a large cluster of ARCI families who resided in the High Mountains Region from the Veracruz State, Mexico. Thus, we aimed to identify the causative mutation of ARCI and describe the high prevalence of this disease in this region. METHODS: We selected seven familiar trios and performed whole-exome sequencing to identify the mutation associated with ARCI. To validate the identified mutation, we performed Sanger sequencing in 62 patients, 30 unaffected relatives, and 100 healthy volunteers. Finally, we performed molecular modeling to investigate the possible functional consequences produced by the mutation. RESULTS: We identified a novel homozygous mutation (c.1054C>G [p.Pro352Ala]) in the exon 7 of the TGM1 gene in all the patients. We calculated a prevalence rate of ARCI of 74:100,000 (1:1,348) in the studied communities. Molecular modeling revealed that the mutation leads to a nonconservative amino acid substitution, which is very probably damaging to the protein structure/function. CONCLUSIONS: We report a novel mutation in the TGM1 gene in 62 Mexican patients. The unusually high frequency of this mutation suggests a founder effect; however, further haplotype analysis is necessary to corroborate this hypothesis. In this respect, to our knowledge, the prevalence of ARCI found in the studied communities is the highest observed worldwide.