Potential Modifying Effect of the APOEε4 Allele on Age of Onset and Clinical Manifestations in Patients with Early-Onset Alzheimer's Disease with and without a Pathogenic Variant in PSEN1 in a Sample of the Mexican Population.

In Alzheimer's disease (AD), the age of onset (AoO) exhibits considerable variability, spanning from 40 to 90 years. Specifically, individuals diagnosed with AD and exhibiting symptoms prior to the age of 65 are typically classified as early onset (EOAD) cases. Notably, the apolipoprotein E (APOE) ε4 allele represents the most extensively studied genetic risk factor associated with AD. We clinically characterized and genotyped the APOEε4 allele from 101 individuals with a diagnosis of EOAD, and 69 of them were affected carriers of the autosomal dominant fully penetrant PSEN1 variant c.1292C>A (rs63750083, A431E) (PSEN1+ group), while there were 32 patients in which the genetic cause was unknown (PSEN1- group). We found a correlation between the AoO and the APOEε4 allele; patients carrying at least one APOEε4 allele showed delays, in AoO in patients in the PSEN1+ and PSEN1- groups, of 3.9 (p = 0.001) and 8.6 years (p = 0.012), respectively. The PSEN1+ group presented higher frequencies of gait disorders compared to PSEN1- group, and apraxia was more frequent with PSEN1+/APOE4+ than in the rest of the subgroup. This study shows what appears to be an inverse effect of APOEε4 in EOAD patients, as it delays AoO and modifies clinical manifestations.

Hematological and molecular analysis of patients with G6PD deficiency revealed coexistent hereditary spherocytosis and alpha thalassemia.

BACKGROUND: Glucose-6-phosphate dehydrogenase (G6PD) deficiency, hereditary spherocytosis (HS), and alpha thalassemia (α-thal) are frequent erythrocyte pathologies with different geographic distributions worldwide. Our aim is to report hematological and molecular findings of G6PD deficient Mexican patients in coinheritance with suggestive hereditary spherocytosis (sHS) and α-thal. METHODS: We studied 78 G6PD deficiency patients. Hematological parameters, acidified glycerol lysis test, erythrocyte morphology, electrophoresis, and hemoglobin quantification were obtained. G6PD and HBA2/HBA1 variants were identified using ARMS-PCR, Gap-PCR, or Sanger sequencing. RESULTS: Nine G6PD variants were identified; A-202A/376G , A-376G/968C , and A+376G as the most frequent. G6PD Santiago de Cuba1339A and Kamiube1387T were detected in Mexicans for first time. Hematological analysis revealed additional erythrocyte pathologies in 52 patients, 32 with positive osmotic fragility test and spherocytes in blood smear (suggestive hereditary spherocytosis, sHS), 12 with microcytosis and 8 with all three defects who had the most severe phenotype, with significantly lower hematological parameters (Hb, PCV, MCV, and MCH). α-thal variants (αHph α, α-59C>T α and -α3.7 ) were observed in 65% of patients with microcytosis. CONCLUSION: Additional erythrocyte defects were observed in 69.3% of G6PD deficiency patients. We stress the importance of searching for the presence of additional erythrocyte hereditary diseases in patients with G6PD deficiency.

Genetic analysis of TMPRSS6 catalytic domain variants in Mexican patients with iron treatment refractoriness.

OBJECTIVE: To identify the TMPRSS6 gene variants in Mexican patients with iron treatment refractoriness, to describe hematological and iron profile parameters, and to use bioinformatic prediction and protein modeling tools to assess a possible biological impact for the detected missense variants. METHODS: Nineteen patients referred with iron treatment refractoriness were studied. Peripheral blood was collected to determine hematic cytometry, iron profile, hemoglobin electrophoresis, and quantification. Molecular screening was carried out for exons 15 through 18 of the TMPRSS6 gene by Sanger sequencing and for frequent thalassemia variants by amplification-refractory mutation system-polymerase chain reaction (PCR) and gap-PCR. The biological impact of the detected missense variants was assessed using bioinformatic prediction and protein modeling tools. RESULTS: We found 5 genetic variants in the matriptase-2 catalytic domain: 1 at intron-15/exon-16 junction (rs60484081) and 4 exonic, 3 missense (rs377054987, p.Gly626Asp; rs1384127820, p.Ser672Thr; rs855791, p.Val727Ala) and 1 synonymous (rs2235321, p.Tyr730=), with frequencies ranging from 0.18 to 0.53. No significant differences were observed in the hematological parameters or iron profile, considering type and number of variants. Bioinformatic predictions suggested a possible biological impact only for rs377054987. CONCLUSIONS: The TMPRSS6 variants observed in Mexican patients with oral iron treatment refractoriness have high frequencies; nevertheless, their relationship with hematological and iron profile parameters needs further research. The possible biological impact for rs377054987 is due to size and amino acid hydrophobicity changes and hydrogen bond modifications.