[Alagille syndrome associated to JAG1 gene deletion. An unusual etiology]. / Síndrome de Alagille por deleción del gen JAG1. Una causa poco frecuente.

Alagille syndrome (ALGS) is an autosomal dominant, multisystem disorder that typically presents with cholestasis, cardiac, ocular, skeletal, vascular and renal abnormalities, and distinct facial features. Most cases are due to variants in the JAG1 gene, with only a small percentage involving a complete gene deletion. OBJECTIVE: to contribute to the phenotype delineation and interpretation of a microdeletion not previously described in the literature on chromosome 20. CLINICAL CASE: A 4-month-old female patient was diagnosed with a heart murmur. An echocardiogram revealed pulmonary artery stenosis, which, combined with a prominent forehead observed on physical examination, determined her referral to clinical genetics. Because ALGS was suspected, complementary studies were performed, revealing butterfly vertebras and a genetic panel identified a pathogenic heterozygous deletion, encompassing the entire coding sequence of the JAG1 gene. To rule out a more extensive deletion, a chromosome microarray was performed, confirming a pathogenic microdeletion on chromosome 20 of 378 kb (arr[GRCh37] 20p12.2(10414643_10792802)x1). CONCLUSIONS: A targeted sequencing panel followed by confirmation with a chromosome microarray allowed the identification and delineation of a pathogenic microdeletion not previously reported in the literature, including the complete JAG1 gene in a Chilean patient whose phenotype is consistent with ALGS.

Variants in BRCA1/2 in a hospital-based cohort in Chile and national literature review.

Purpose: The aim was to assess the diagnostic yield of next generation sequencing (NGS) multi-gene panels for breast and ovarian cancer in a high-complexity cancer centre in Chile. Additionally, our goal was to broaden the genotypic spectrum of BRCA variants already identified in Chilean families. Methods: Retrospective analysis was conducted on the genetic test results of 722 individuals from Fundación Arturo López Pérez's genetic counselling unit between 2016 and 2021. A comprehensive literature review encompassing articles analysing the frequency of germinal pathogenic variants in BRCA1/2 within the Chilean population was undertaken. Results: 23.5% of the panels had positive results, with 60% due to pathogenic variants in the BRCA1/2 genes. Seven previously unreported variants in BRCA1 from Chilean studies were identified.One or more variants of uncertain significance were detected in 31% of the results, and 11.5% of the families in this cohort presented copy number variants (CNVs) in BRCA1/2.8 studies analysed the frequency of pathogenic variants in BRCA1/2 in the Chilean population between 2006 and 2023, with a frequency between 7.1% and 17.1%.51 BRCA1 variants in 149 families have been reported in Chile and 38 BRCA2 variants in 132 families. Nine founder pathogenic variants identified by one study were present in 51.9% of the total Chilean families reported. Conclusion: Our findings advocate for the integration of NGS multi-gene panel testing as a primary strategy within our population. This approach allows for the comprehensive assessment of single nucleotide variants and CNVs in BRCA1/2, alongside other high and moderately penetrant genes associated with breast and ovarian cancer.

The Phenotypic Spectrum of Spinocerebellar Ataxia Type 19 in a Series of Latin American Patients.

Spinocerebellar ataxia 19 (SCA19) represents a rare autosomal dominant genetic disorder resulting in progressive ataxia and cerebellar atrophy. SCA19 is caused by variants in the KCND3 gene, which encodes a voltage-gated potassium channel subunit essential for cerebellar Purkinje cell function. We describe six cases from Chile and Mexico, representing the largest report on SCA19 in Latin America. These cases encompass a range of clinical presentations, highlighting the phenotypic variability within SCA19 from an early-onset, severe disease to a late-onset, slowly progressive condition with normal lifespan. While some patients present with pure ataxia, others also show cognitive impairment, dystonia, and other neurological symptoms. The correlations between specific KCND3 variants and phenotypic outcomes are complex and warrant further investigation. As the genomic landscape of spinocerebellar ataxias evolves, comprehensive genetic testing is becoming pivotal in improving diagnostic accuracy. This study contributes to a better understanding of the clinical spectrum of SCA19, laying the groundwork for further genotype-phenotype correlations and functional studies to elucidate the underlying pathophysiology.

Riesgo de Esquizofrenia y Síndrome Deleción 22Q11. 2 / RIsk of schizophrenia and 22q11. 2 deletion syndrome

INTRODUCCIÓN. La deleción 22q11.2 es una alteración cromosómica muy frecuente, en la cual un 60% de los afectados presenta patologías neuropsiquiátricas. Determinar si existe asociación entre el síndrome de deleción 22q11.2 (SD22q11.2) y patologías como la esquizofrenia (EQZ), ofrece una oportunidad para la intervención temprana, y seguimiento de personas con este síndrome. OBJETIVO. El objetivo del presente trabajo es determinar si existe mayor riesgo de EQZ en pacientes con síndrome deleción 22q11.2. MÉTODOS. Se realizó una búsqueda bibliográfica sistemática de publicaciones con fecha de 1990 a 2020. Las búsquedas se realizaron en PubMed y en la base de datos Cochrane. En total, se evaluaron 19 estudios, de los que se consideraron elegibles diez publicaciones para el análisis, lo que corresponde a 824 participantes. RESULTADOS. El riesgo de presentar EQZ en un individuo con SD22q11.2 es de 20-25%, en comparación al 1% de la población general. CONCLUSIONES. El riesgo para un individuo con SD22q11.2 de presentar EQZ se encuentra bien establecido. Considerar este riesgo podría ayudar a un adecuado seguimiento y una intervención temprana.

INTRODUCTION. 22q11.2 deletion syndrome is a very common chromosomal abnormality, in which 60% of those affected have neuropsychiatric disorders. Determining if there is an association between 22q11.2 deletion syndrome (22q11.2DS) and disorders such as schizophrenia (SCZ) offers an opportunity for early intervention and follow-up of people with this syndrome. OBJECTIVE. The objective of this study is to determine if there is a greater risk of SCZ in patients with 22q11.2 deletion syndrome. METHODS. A systematic review was performed for publications dated 1990 to 2020. The strategy was to search in PubMed and Cochrane databases for specific MeSH terms. In total, 19 studies were reviewed, of which 10 publications were eligible for analysis, corresponding to 824 participants. RESULTS. The risk of presenting SCZ in an individual with 22q11.2DS is 20-25%, compared to 1% in the general population.CONCLUSIONS. The risk of presenting SCZ in an individual with 22q11.2DS is well established. Considering this risk could help with adequate follow-up and early intervention.