Prevalence and spectrum of germline pathogenic variants in cancer susceptibility genes among mexican patients with exocrine pancreatic cancer.

BACKGROUND: Although universal germline genetic testing is recommended for patients with exocrine pancreatic cancer (PC), access to genetic testing remains limited in low- and middle-income countries. This study aims to narrow the gap in our understanding of the spectrum of germline pathogenic and likely pathogenic variants (PVs) in cancer susceptibility genes in the Mexican population. METHODS: The landscape of PVs in cancer susceptibility genes was identified by next-generation sequencing multigene panel assays among patients with PC who were enrolled in the Clinical Cancer Genomics Community Research Network prospective registry in Mexico City. RESULTS: From August 2019 to April 2023, 137 patients underwent genetic testing. The median age at diagnosis was 60 years (range 36-85), 58.4 % were women, and 38.7 % were metastatic at diagnosis. The frequency of germline PVs was 16 % (n = 22): ATM 36.4 % (n = 8), CDKN2A/p16INK4A 27.3 % (n = 6), BRCA2 9.1 % (n = 2), PALB2 9.1 % (n = 2), CHEK2 9.1 % (n = 2), TP53 4.5 % (n = 1), and NF1 4.5 % (n = 1). Additionally, 2 carriers of monoallelic germline variants in MUTYH were identified. No significant differences were observed between carriers and non-carriers in terms of family history of pancreatic cancer. CONCLUSIONS: We identified a significant frequency of actionable germline PVs in Mexicans with PC, wherein the majority were in a broad spectrum of genes associated with the homologous recombination DNA repair mechanism. Most pancreatic cancer associated PVs were detected in non-BRCA genes, so our findings support the recommendation of multigene panel testing for genetic cancer risk assessment of Mexican individuals with PC.

Recognizing Lipofuscinosis as a Guide in Antiepileptic Treatment: Clinical Description of the First Mexican Case With Neuronal Ceroid Lipofuscinosis Type 7 (NCL7).

Neuronal ceroid lipofuscinosis type 7 (NCL7) is a rare form of childhood dementia; it is part of a group of diseases characterized by rapid progressive cognitive decline, blindness associated with retinitis pigmentosa, and seizures. We report the clinical and molecular characteristics of the first Mexican patient with NCL7, highlighting a particularly atypical disease course. The typical presentation form is expected to have reduced life expectancy and an average age of ambulation loss at 12 years. Our 27-year-old patient retains the ability to walk. The patient's unique presentation could, in part, be attributed to her genetic profile: a hypomorphic allele carrying a missense variant (c.1390G>A) and an almost null allele with a frameshift variant (c.1086del), contributing to the preservation of some protein function. Throughout her childhood and early adulthood, our patient experienced a variable response to antiseizure drugs, attributed to a lack of recognition of the disease and the specific efficacy of certain antiseizure medications. Our findings underscore the significance of considering this genetic condition and acknowledging its clinical heterogeneity.

Genotype and phenotype characterization of primary hypertrophic osteoarthropathy type 2 and chronic enteropathy associated with SLCO2A1: Report of two cases and literature review.

Autosomal recessive type 2 primary hypertrophic osteoarthropathy (PHOAR2) and chronic enteropathy associated with SLCO2A1 (CEAS) are two entities caused by pathogenic variants (PVs) in the SLCO2A1 gene that can coexist or occur independently from one another. We report two cases of PHOAR2 in Mexico with concomitant CEAS and conducted a review of the literature of the reported cases of PHOAR2 and/or CEAS to analyze the relationship between their genotype and phenotype presentation. The patients from our Institution with classical PHOAR2 phenotype and CEAS, harbored SLCO2A1 c.547G > A and c.1768del variants. We reviewed 232 cases, of which 86.6% were of Asian origin, and identified 109 different variants in SLCO2A1. Intron 7, exon 13, and exon 4 were predominantly affected. The two most common PVs were c.940 + 1G > A and c.1807C > T. We found a statistically significant association between SLCO2A1 variants located in intron 7, exons 12, and 13 and the development of CEAS. Missense variants were more frequent in isolated PHOAR2, while a greater proportion of protein-truncating variants (PTVs) were found in CEAS. Further investigation is imperative to elucidate the underlying pathophysiological mechanisms associated with CEAS, thereby facilitating the identification of effective therapeutic interventions.

Vitamin D Hydroxylation-deficient Rickets Type 1A Misdiagnosed as Normocalcemic Primary Hyperparathyroidism.

Vitamin D hydroxylation-deficient rickets type 1A is an autosomal recessive disorder caused by pathogenic variants in CYP27B1 gene, which encodes for 1α-hydroxylase, the enzyme responsible for the conversion of 25-OH vitamin D into its active form 1,25(OH)2 vitamin D. We report the case of a 3-year-old female Mexican patient with growth retardation and progressive bone deformity, whose laboratory studies showed 25-OH vitamin D deficiency, a normal serum calcium and an elevated intact parathyroid hormone level that remained high despite calcitriol, cholecalciferol, and calcium supplementation. 99mTc sestamibi gammagram showed findings suggestive of parathyroid hyperplasia. Bone histomorphometry showed an image consistent with hyperparathyroidism without findings of osteomalacia, so normocalcemic primary hyperparathyroidism was suspected and a subtotal parathyroidectomy was performed, with the patient developing postoperative hypoparathyroidism. When she arrived at our clinic at age 18 years, she showed calcium- and calcitriol-dependent hypocalcemia, with secondary hyperparathyroidism and low levels of 1,25(OH)2 vitamin D in the absence of a 25-OH vitamin D deficiency, reflecting a defect in 1α-hydroxylation. Molecular testing revealed compound heterozygous variants in CYP27B1 gene. This is the first reported case of an inherited disorder of vitamin D metabolism that was diagnosed and surgically treated as primary hyperparathyroidism.

Esophageal stenosis in an adult Mexican patient with diastrophic dysplasia: Case report.

Diastrophic dysplasia (DTD) is caused by biallelic pathogenic variants in the SLC26A2 gene. We report the case of a 49-year-old female with DTD and esophageal stenosis. This broadens the phenotypic spectrum in adult patients with DTD and raises awareness of extra-skeletal manifestations that could develop in later stages of life.

Inherited bone marrow failure syndromes: phenotype as a tool for early diagnostic suspicion at a major reference center in Mexico.

Introduction: The inherited bone marrow failure syndromes (IBMFSs) are a group of rare disorders characterized by bone marrow failure (BMF), physical abnormalities, and an increased risk of neoplasia. The National Institute of Pediatrics (INP) is a major medical institution in Mexico, where patients with BMF receive a complete approach that includes paraclinical tests. Readily recognizable features, such as the hematological and distinctive physical phenotypes, identified by clinical dysmorphologists, remain crucial for the diagnosis and management of these patients, particularly in circumstances where next-generation sequencing (NGS) is not easily available. Here, we describe a group of Mexican patients with a high clinical suspicion of an IBMFS. Methods: We performed a systematic retrospective analysis of the medical records of patients who had a high IBMFS suspicion at our institution from January 2018 to July 2021. An initial assessment included first ruling out acquired causes of BMF by the Hematology Department and referral of the patient to the Department of Human Genetics for physical examination to search for specific phenotypes suggesting an IBMFS. Patients with high suspicion of having an IBMFS were classified into two main groups: 1) specific IBMFS, including dyskeratosis congenita (DC), Diamond-Blackfan anemia (DBA), Shwachman-Diamond syndrome (SDS), thrombocytopenia with absent radii (TAR), and severe congenital neutropenia (SCN); 2) undefined IBMFS (UI). Results: We established a high suspicion of having an IBMFS in 48 patients. At initial evaluation, the most common hematologic features were bicytopenia (20%) and aplastic anemia (16%); three patients received hematopoietic stem cell transplantation. Among patients with a suspicion of an IBMFS, the most common physical abnormality was minor craniofacial features in 83% of patients and neurodevelopmental disorders in 52%. The specific suspicions that we built were DBA (31%), SDS (18%), DC (14%), TAR (4%), and SCN (4%), whereas 27% of cases remained as undefined IBMFS. SDS, TAR, and SCN were more commonly suspected at an earlier age (<1 year), followed by DBA (2 years) and DC (5 years). Conclusions: Thorough examination of reported clinical data allowed us to highly suspect a specific IBMFS in approximately 70% of patients; however, an important number of patients remained with suspicion of an undefined IBMFS. Implementation of NGS and telomere length measurement are forthcoming measures to improve IBMFS diagnosis in Mexico.