A neurodegenerative disease landscape of rare mutations in Colombia due to founder effects.

BACKGROUND: The Colombian population, as well as those in other Latin American regions, arose from a recent tri-continental admixture among Native Americans, Spanish invaders, and enslaved Africans, all of whom passed through a population bottleneck due to widespread infectious diseases that left small isolated local settlements. As a result, the current population reflects multiple founder effects derived from diverse ancestries. METHODS: We characterized the role of admixture and founder effects on the origination of the mutational landscape that led to neurodegenerative disorders under these historical circumstances. Genomes from 900 Colombian individuals with Alzheimer's disease (AD) [n = 376], frontotemporal lobar degeneration-motor neuron disease continuum (FTLD-MND) [n = 197], early-onset dementia not otherwise specified (EOD) [n = 73], and healthy participants [n = 254] were analyzed. We examined their global and local ancestry proportions and screened this cohort for deleterious variants in disease-causing and risk-conferring genes. RESULTS: We identified 21 pathogenic variants in AD-FTLD related genes, and PSEN1 harbored the majority (11 pathogenic variants). Variants were identified from all three continental ancestries. TREM2 heterozygous and homozygous variants were the most common among AD risk genes (102 carriers), a point of interest because the disease risk conferred by these variants differed according to ancestry. Several gene variants that have a known association with MND in European populations had FTLD phenotypes on a Native American haplotype. Consistent with founder effects, identity by descent among carriers of the same variant was frequent. CONCLUSIONS: Colombian demography with multiple mini-bottlenecks probably enhanced the detection of founder events and left a proportionally higher frequency of rare variants derived from the ancestral populations. These findings demonstrate the role of genomically defined ancestry in phenotypic disease expression, a phenotypic range of different rare mutations in the same gene, and further emphasize the importance of inclusiveness in genetic studies.

[Colombian Guidelines of clinical practice for the use of immunoglobulins in the treatment of replacement and immunomodulation]. / Guía colombiana de práctica clínica para el uso de inmonuglobulinas en el tratamiento de reemplazo e inmunomodulación.

Immunoglobulins are heterodimeric proteins composed of 2 heavy chains and 2 light chains. Human immunoglobulin G (IgG) is a plasma derivative and contains more than 95% of IgG. The composition of IgG subclasses is similar to that of normal human plasma. Immunoglobulin therapy was first introduced more than 50 years ago, and its use has been described in numerous diseases. In Colombia, the importance of this immunomodulatory resource prompted the need for clinical practice guidelines to be available for its use. For this reason, a multidisciplinary group of experts was brought together and distributed in working groups, by specialties, in order to develop an initial manuscript. Systematic literature searches were undertaken; identified evidences were evaluated and classified to support a preliminary draft that was discussed, analyzed and amended. Recommendations were issued on the use of intravenous immunoglobulin in pathologies that include primary and secondary immunodeficiencies, autoimmune diseas es, neurological disorders, infections, transplants and miscellaneous conditions; grades were assigned to each one of them according to the GRADE system. The final result translated into recommendations that are put forth with the purpose to inform, guide and support on optimal use of this immunomodulatory resource.

Las inmunoglobulinas son proteínas heterodiméricas compuestas de 2 cadenas pesadas y 2 cadenas ligeras. La inmunoglobulina G humana es un derivado del plasma y contiene más de 95 % de IgG. La composición de las subclases de IgG es similar a la del plasma humano normal. El tratamiento con inmunoglobulina comenzó hace más de 50 años y su uso se ha descrito en numerosas enfermedades. En Colombia, la importancia de este recurso inmunomodulador condujo a la necesidad de contar con una guía de práctica clínica para su uso, para lo cual se reunió un grupo multidisciplinario de expertos, quienes se distribuyeron en mesas de trabajo, por especialidad, para redactar un texto base. Se llevaron a cabo búsquedas bibliográficas sistemáticas; las evidencias identificadas se valoraron y clasificaron para sustentar un texto preliminar que fue discutido, analizado y corregido. Se emitieron recomendaciones de uso de la inmunoglobulina intravenosa en patologías que abarcan inmunodeficiencias primarias y secundarias, enfermedades autoinmunes, alteraciones neurológicas, infecciones, trasplantes y enfermedades misceláneas; se asignaron calificaciones según el sistema GRADE para cada una. El resultado final se tradujo en las recomendaciones que se presentan con la finalidad de informar, orientar y apoyar en el uso óptimo de dicho recurso inmunomodulador.