Background: Atopic dermatitis (AD) is a chronic multifactorial allergic disease with unclear etiology. The antimicrobial human β-defensin 1 is chemotactic for dendritic cells, which are important regulators of allergic immune responses. In an attempt to identify useful markers that could predict susceptibility to AD, we investigated single nucleotide polymorphisms (SNPs) of the β-defensin 1 gene (DEFB1) with potential functional consequences. Methods: Four SNPs of the DEFB1 gene were genotyped either by real-time polymerase chain reaction or polymerase chain reaction-restriction fragment length polymorphisms in 59 patients with AD and 151 controls from the Mexican population. Correlation analyses were carried out between genetic, environmental and clinical variables in AD patients. Results: The genotypes associated with susceptibility to AD and no other allergy were 692 GG (OR = 3.21, 95% CI 1.37–7.34) and 1654 AA (OR = 17.37, 95% CI 1.62–860.83). The allele 668 C is a risk factor for AD (OR = 2.23, 95% CI 1.22–4.01) and the allele A in site 1836 correlates with earlier age at onset (Spearman’s ρ = 0.232; p = 0.03). The prolonged duration of breastfeeding correlates with earlier age at onset as well as with the severity of AD. Conclusions: The DEFB1 gene is probably involved in the incidence and development of AD, but additional functional studies will be necessary to understand the biological role of these SNPs.

A 5-year-old Mexican girl had a bilateral, systematized epidermal nevus of a non-epidermolytic, non-organoid type covering large parts of her body with the exception of the scalp. Clinically, this nevus was of a soft, velvety type showing affinity to the large body folds. Histopathological examination revealed orthohyperkeratosis and papillomatosis without granular degeneration and without any abnormality of adnexal structures. During infancy she developed seizures, and subsequently a delayed mental development was noted. Computer tomography of the brain revealed cortical and subcortical atrophy, a subdural hygroma in the left frontoparietotemporal region, and hypoplasia of corpus callosum. Molecular analysis of a biopsy specimen obtained from the epidermal nevus revealed a heterozygous R248C hotspot mutation in FGFR3, whereas in normal skin the FGFR3 wild-type allele was exclusively found. The R248C mutation was also present in DNA extracted from blood leukocytes. Because FGFR3 is involved in the development of the central nervous system, the clinical and genetic findings of this case indicate a widespread mosaicism of the FGFR3 mutation. This unusual mosaic phenotype may represent a distinct entity within the group of epidermal nevus syndromes.

A nonsense mutation was identified in the first family with HSS of Latin American ethnical background. Our data provide molecular genetic evidence for a 3rd stop mutation in exon 2 of the CDSN gene being responsible for HSS. All to date known nonsense mutations responsible 3 for HSS are clustered in a region of 40 amino acids which is in accordance with a dominant negative effect conferred by aggregates of truncated CDSN proteins.

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Background The infection by coronavirus disease 2019 (COVID‐19) has been associated with multiple cutaneous manifestations, although characterization of them in Hispanic patients with darker skin phototypes is lacking. The objective of this study is to characterize the clinical dermatological manifestations associated with COVID‐19 infection in cases with few or without general symptoms in patients from Latin America. Methods Cross‐sectional study using a questionnaire that was made for health professionals (physicians with a specialty in dermatology) to investigate dermatological lesions associated with COVID‐19 infection in patients from 25 countries of Latin America. The survey was active from June 9 to July 30, 2020. Results In this study, information was collected from a total of 347 patients. We found a female gender predominance: 179/347 (51.6%). The mean age at presentation was 40.87 years. The most frequent dermatological manifestations were maculopapular rash and urticarial lesions, followed by papulovesicular lesions, vesicular lesions, chilblain‐like lesions, papular lesions, ecchymosis, petechial purpura, pityriasis rosea‐like lesions, pruritus, palmoplantar dysesthesias, transient livedo, acral necrosis, palpable purpura, livedo racemosa, and retiform purpura. As far as we know, there are no previous reports of pruritus and palmoplantar dysesthesias. Conclusions This registry emphasizes skin manifestations as an important criterion for establishing the diagnosis of COVID‐19 infection in Latin American countries. This information will be useful for the early identification of suspected cases by health professionals (dermatologists and nondermatologists) and will allow contact tracing to mitigate the impact on health systems at different levels.