[Risk factors in the origin of Down syndrome]

Abstract Down syndrome (DS) is the most common autosomal aneuploidy and the leading cause of intellectual disability of genetic origin worldwide. It is identified as a syndrome in which the variability of its clinical manifestations and the severity of its phenotype have a multifactorial origin. Worldwide prevalence ranges between 1 per 700 live births and several factors that may be involved in the origin of DS have been proposed. Our objective was to describe updates regarding risk factors in the cytogenetic origin or cause of DS. We conducted a narrative review study in which a literature search was carried out from January to June 2022 in databases such as PubMed, EBSCO, Medigraphic, ClinicalKey, and meta-search engines such as Elsevier and Evidence Alerts. Only articles published in the last 10 years in English and Spanish were included. The search terms used were: Down syndrome, risk factors, prevention. Although DS is a very common chromosomal pathology worldwide, there is no single risk factor at the origin of meiotic or mitotic nondisjunction of chromosome 21, but rather each of the associated risk factors contributes to a greater or lesser degree to a cytogenetic predisposition in the etiology of trisomy 21. During the review it was identified that the main established risk factor associated with DS is still advanced maternal age (≥ 35 years). Resumen El síndrome de Down (SD) es la aneuploidía de autosomas más frecuente y la primera causa de discapacidad intelectual de origen genético a nivel mundial. Se identifica como una condición de vida en la que la variabilidad de sus manifestaciones clínicas y la gravedad del fenotipo tienen un origen multifactorial. La prevalencia mundial oscila entre 1 por cada 700 nacidos vivos y se han propuesto diversos factores de riesgo que pueden estar implicados en el origen del SD. Nuestro objetivo fue describir las actualizaciones con respecto a los factores de riesgo en el origen o causa citogenética del SD. Se realizó una revisión narrativa en la cual se condujo una búsqueda bibliográfica en el periodo de enero a junio de 2022 en bases de datos como PubMed, EBSCO, Medigraphic, ClinicalKey y metabuscadores como Elsevier y Evidence Alerts. Se incluyeron únicamente artículos publicados en los últimos 10 años en idioma inglés y español. Los términos de búsqueda utilizados fueron: Down syndrome, risk factors, prevention. Aunque el SD es una patología cromosómica muy frecuente a nivel internacional, no existe un factor de riesgo único en el origen de la no disyunción meiótica o mitótica del cromosoma 21, sino que cada uno de los factores de riesgo asociados contribuye en mayor o menor medida a una predisposición citogenética en la etiología de la trisomía 21. Durante la revisión se identificó que el principal factor de riesgo establecido asociado a SD sigue siendo la edad materna avanzada (≥ 35 años)

Mitochondrial proteomic profile of complex IV deficiency fibroblasts: rearrangement of oxidative phosphorylation complex/supercomplex and other metabolic pathways

Background: Mitochondriopathies are multisystem diseases affecting the oxidative phosphorylation (OXPHOS) system. Skin fibroblasts are a good model for the study of these diseases. Fibroblasts with a complex IV mitochondriopathy were used to determine the molecular mechanism and the main affected functions in this disease. Methods: Skin fibroblast were grown to assure disease phenotype. Mitochondria were isolated from these cells and their proteome extracted for protein identification. Identified proteins were validated with the MitoMiner database. Results: Disease phenotype was corroborated on skin fibroblasts, which presented a complex IV defect. The mitochondrial proteome of these cells showed that the most affected proteins belonged to the OXPHOS system, mainly to the complexes that form supercomplexes or respirosomes (I, III, IV, and V). Defects in complex IV seemed to be due to assembly issues, which might prevent supercomplexes formation and efficient substrate channeling. It was also found that this mitochondriopathy affects other processes that are related to DNA genetic information flow (replication, transcription, and translation) as well as beta oxidation and tricarboxylic acid cycle. Conclusions: These data, as a whole, could be used for the better stratification of these diseases, as well as to optimize management and treatment options

Clinical, radiological, and molecular diagnosis of progressive fibrodysplasia ossificans

Background: Progressive fibrodysplasia ossificans is a rare genetic disease with heterozygous mutations (autosomal dominant inheritance) in the ACVR1 gene, which causes progressive heterotopic ossification in muscles, tendons, and ligaments, usually secondary to trauma. The ossification foci generate pain, joint ankyloses, and restricted movement. Congenital shortening and medial deviation first metatarsal of the foot is a distinctive feature. This report aimed to present an educational value case of a patient with clinical, imaging, and molecular diagnosis of progressive fibrodysplasia ossificans, recognized as a rare condition that severely affects the quality of life. Case report: We present the case of a 6-year-old female patient with lumps in the right scapular and dorsal region, progressive joint rigidity, and short first metatarsal medially deviated since birth. By imaging studies, we established the diagnosis of progressive fibrodysplasia ossificans. Sanger sequencing of ACVR1 reported c.617G>A (p.Arg206His). Conclusions: Confirmation of the diagnosis allowed genetic counseling, including a comprehensive explanation of the disease’s natural history and measures to prevent its rapid progression

Clustering of Genetic Anomalies of Cilia Outer Dynein Arm and Central Apparatus in Patients with Transposition of the Great Arteries

Transposition of the great arteries (TGA) is a congenital heart defect with a complex pathogenesis that has not been fully elucidated. In this study, we performed whole-exome sequencing (WES) in isolated TGA-diagnosed patients and analyzed genes of motile and non-motile cilia ciliogenesis and ciliary trafficking, as well as genes previously associated with this heart malformation. Deleterious missense and splicing variants of genes DNAH9, DNAH11, and ODAD4 of cilia outer dynein arm and central apparatus, HYDIN, were found in our TGA patients. Remarkable, there is a clustering of deleterious genetic variants in cilia genes, suggesting it could be an oligogenic disease. Our data evidence the genetic diversity and etiological complexity of TGA and point out that population allele determination and genetic aggregation studies are required to improve genetic counseling