Analysis of COL7A1 pathogenic variants in a large cohort of dystrophic epidermolysis bullosa patients from Argentina reveals a new genotype-phenotype correlation.

Dystrophic epidermolysis bullosa (DEB) is a clinically heterogeneous heritable skin disorder, characterized by blistering of the skin and mucous membranes following minor trauma. Dominant (DDEB) and recessive (RDEB) forms are caused by pathogenic variants in COL7A1 gene. Argentina's population has a heterogeneous genetic background, and little is known about the molecular basis of DEB in our country or in native South American populations. In this study, we present the prevalence and geographical distribution of pathogenic variants found in 181 patients from 136 unrelated families (31 DDEB and 105 RDEB). We detected 95 different variants, 59 of them were previously reported in the literature and 36 were novel, nine of which were detected in more than one family. The most prevalent pathogenic variants were identified in exon 73 in DDEB patients and in exon 3 in RDEB patients. We also report a new phenotype-genotype correlation found in 10 unrelated families presenting mild blistering and severe mucosal involvement. Molecular studies in populations with an unexplored genetic background like ours revealed a diversity of pathogenic variants, and we hope that these findings will contribute to the definition of targets for new gene therapies.

Ichthyosis follicularis, atrichia and photophobia (IFAP) and hereditary mucoepithelial dysplasia: Two syndromes that share a common clinical spectrum.

Ichthyosis follicularis, atrichia and photophobia syndrome (IFAP) is an X-linked inherited disease caused by pathogenic variants in the gene encoding the membrane-bound transcription factor peptidase, site 2 (MBTPS2). Clinical presentation includes ichthyosis follicularis, alopecia, photophobia and developmental delay. Hereditary mucoepithelial dysplasia (HMD) is a dominantly inherited disease characterized by keratitis, non-scarring alopecia, skin lesions including follicular keratosis, perineal erythema, and mucosal involvement. Recently, variants in SREBF1, a gene coding for a transcription factor related to cholesterol and fatty acid synthesis, have been associated with the disease. These two syndromes share a common clinical spectrum. Here, we describe an IFAP syndrome patient with a novel variant in the MBTPS2 gene and an HMD patient with a previously reported variant in the SREBF1 gene. In addition, we present a review of the literature describing the triad characterized by non-scarring alopecia, keratosis follicularis, and ocular symptoms common in both IFAP and HMD patients to raise awareness of these underdiagnosed diseases. We also highlight the subtle differences in clinical presentation between the two disorders to better enable differentiation.

A novel pathogenic FERMT1 variant in four families with Kindler syndrome in Argentina.

BACKGROUND: Kindler syndrome is a rare genodermatosis. Major clinical criteria include acral blistering in infancy and childhood, progressive poikiloderma, skin atrophy, abnormal photosensitivity, and gingival fragility. METHODS: FERMT1 gene was sequenced in 5 patients with a clinical diagnosis of Kindler syndrome. RESULTS: We report a novel pathogenic variant detected in four unrelated families of Paraguayan origin, where one nucleotide deletion in FERMT1 gene (c.450delG) is predicted to cause a frameshift mutation leading to loss of function. Haplotype analysis revealed the propagation of an ancestral allele through this population. CONCLUSIONS: The identification of this recurrent pathogenic variant enables optimization of molecular detection strategies in our patients, reducing the cost of diagnosis.

Dengue Virus 1 Outbreak in Buenos Aires, Argentina, 2016.

The largest outbreak of dengue in Buenos Aires, Argentina, occurred during 2016. Phylogenetic, phylodynamic, and phylogeographic analyses of 82 samples from dengue patients revealed co-circulation of 2 genotype V dengue virus lineages, suggesting that this virus has become endemic to the Buenos Aires metropolitan area.

Assessing the hidden diversity underlying consensus sequences of SARS-CoV-2 using VICOS, a novel bioinformatic pipeline for identification of mixed viral populations.

INTRODUCTION: Coinfection with two SARS-CoV-2 viruses is still a very understudied phenomenon. Although next generation sequencing methods are very sensitive to detect heterogeneous viral populations in a sample, there is no standardized method for their characterization, so their clinical and epidemiological importance is unknown. MATERIAL AND METHODS: We developed VICOS (Viral COinfection Surveillance), a new bioinformatic algorithm for variant calling, filtering and statistical analysis to identify samples suspected of being mixed SARS-CoV-2 populations from a large dataset in the framework of a community genomic surveillance. VICOS was used to detect SARS-CoV-2 coinfections in a dataset of 1,097 complete genomes collected between March 2020 and August 2021 in Argentina. RESULTS: We detected 23 cases (2%) of SARS-CoV-2 coinfections. Detailed study of VICOS's results together with additional phylogenetic analysis revealed 3 cases of coinfections by two viruses of the same lineage, 2 cases by viruses of different genetic lineages, 13 were compatible with both coinfection and intra-host evolution, and 5 cases were likely a product of laboratory contamination. DISCUSSION: Intra-sample viral diversity provides important information to understand the transmission dynamics of SARS-CoV-2. Advanced bioinformatics tools, such as VICOS, are a necessary resource to help unveil the hidden diversity of SARS-CoV-2.

The Lambda Variant in Argentina: Analyzing the Evolution and Spread of SARS-CoV-2 Lineage C.37.

The second wave of COVID-19 occurred in South America in early 2021 and was mainly driven by Gamma and Lambda variants. In this study, we aimed to describe the emergence and local genomic diversity of the SARS-CoV-2 Lambda variant in Argentina, from its initial entry into the country until its detection ceased. Molecular surveillance was conducted on 9356 samples from Argentina between October 2020 and April 2022, and sequencing, phylogenetic, and phylogeographic analyses were performed. Our findings revealed that the Lambda variant was first detected in Argentina in January 2021 and steadily increased in frequency until it peaked in April 2021, with continued detection throughout the year. Phylodynamic analyses showed that at least 18 introductions of the Lambda variant into the country occurred, with nine of them having evidence of onward local transmission. The spatial--temporal reconstruction showed that Argentine clades were associated with Lambda sequences from Latin America and suggested an initial diversification in the Metropolitan Area of Buenos Aires before spreading to other regions in Argentina. Genetic analyses of genome sequences allowed us to describe the mutational patterns of the Argentine Lambda sequences and detect the emergence of rare mutations in an immunocompromised patient. Our study highlights the importance of genomic surveillance in identifying the introduction and geographical distribution of the SARS-CoV-2 Lambda variant, as well as in monitoring the emergence of mutations that could be involved in the evolutionary leaps that characterize variants of concern.

Cost-Effective Method to Perform SARS-CoV-2 Variant Surveillance: Detection of Alpha, Gamma, Lambda, Delta, Epsilon, and Zeta in Argentina.

SARS-CoV-2 variants with concerning characteristics have emerged since the end of 2020. Surveillance of SARS-CoV-2 variants was performed on a total of 4,851 samples from the capital city and 10 provinces of Argentina, during 51 epidemiological weeks (EWs) that covered the end of the first wave and the ongoing second wave of the COVID-19 pandemic in the country (EW 44/2020 to EW 41/2021). The surveillance strategy was mainly based on Sanger sequencing of a Spike coding region that allows the identification of signature mutations associated with variants. In addition, whole-genome sequences were obtained from 637 samples. The main variants found were Gamma and Lambda, and to a lesser extent, Alpha, Zeta, and Epsilon, and more recently, Delta. Whereas, Gamma dominated in different regions of the country, both Gamma and Lambda prevailed in the most populated area, the metropolitan region of Buenos Aires. The lineages that circulated on the first wave were replaced by emergent variants in a term of a few weeks. At the end of the ongoing second wave, Delta began to be detected, replacing Gamma and Lambda. This scenario is consistent with the Latin American variant landscape, so far characterized by a concurrent increase in Delta circulation and a stabilization in the number of cases. The cost-effective surveillance protocol presented here allowed for a rapid response in a resource-limited setting, added information on the expansion of Lambda in South America, and contributed to the implementation of public health measures to control the disease spread in Argentina.

Diagnóstico molecular de paquioniquia congénita / Molecular diagnosis of congenital pachyonychia

La paquioniquia congenital (PC) es una genodermatosis poco frecuente, caracterizada por presentar queratodermia palmoplantar dolorosa y debilitante, uñas hipertróficas, hiperqueratosis folicular, quistes epidérmicos, leucoqueratosis oral y ocasionalmente hiperhidrosis, ronquera y dientes natales. Está asociada a mutaciones heterocigotas en los genes que codifican queratinas 6a, 6b, 6c, 16 y 17. Se presenta una familia con dos miembros en dos generaciones afectados por PC: un niño de 2 años de edad con alteración de la coloración, hiperqueratosis de las 20 uñas, con dolor periungueal, múltiples pápulas foliculares color piel en tronco y dientes natales y su madre, con alteración del esmalte dentario, distrofia hipertrófica de las 20 uñas, cromoniquia, queratodermia plantar dolorosa y múltiples esteatocistomas de distribución generalizada.En ambos, se realizó el diagnóstico molecular por secuenciación masiva de exoma clínico, el cual confirmó el diagnóstico clínico y permitió determinar inequívocamente el tipo de PC en el niño, motivo de ésta presentación.

Pachyonychia congenital (PC) is a rare genodermatosis characterized by painful palmoplantar keratoderma, hypertrophic nail dystrophy, follicular hyperkeratosis, epidermal cysts, oral leukokeratosis and, less commonly, palmoplantar hyperhidrosis, hoarseness and natal teeth. PC is caused by mutations in keratin 6a, 6b, 6c, 16 and 17 genes. We report a family with two members in two generations affected by PC: a two-year old boy, presenting abnormal pigmentation and hyperkeratosis of the 20 nails, perionychium pain, multiple skin-colored follicular papules on the trunk and natal teeth. His mother has dental enamel defects, hypertrophic dystrophy of the fingernails and toenails, chromonychia, painful plantar keratoderma and generalized steatocystoma multiplex. We performed the molecular diagnosis by clinical exome massive sequencing which allowed us to confirm the clinical diagnosis and to determine the specific type of PC in our patient.