RESUMEN
A hexanucleotide repeat expansion in chromosome 9 open reading frame 72 (C9orf72) can cause amyotrophic lateral sclerosis (ALS) and/or frontotemporal dementia (FTD). We assessed its frequency in 781 sporadic ALS (sALS) and 155 familial ALS (fALS) cases, and in 248 Spanish controls. We tested the presence of the reported founder haplotype among mutation carriers and in 171 Ceph Europeans from Utah (CEU), 170 Yoruba Africans, 81 Han Chinese, and 85 Japanese subjects. The C9orf72 expansion was present in 27.1% of fALS and 3.2% of sALS. Mutation carriers showed lower age at onset (P = 0.04), shorter survival (P = 0.02), greater co-occurrence of FTD (P = 8.2 × 10(-5)), and more family history of ALS (P = 1.4 × 10(-20)), than noncarriers. No association between alleles within the normal range and the risk of ALS was found (P = 0.12). All 61 of the mutation carriers were tested and a patient carrying 28 hexanucleotide repeats presented with the founder haplotype. This haplotype was found in 5.6% Yoruba Africans, 8.9% CEU, 3.9% Japanese, and 1.6% Han Chinese chromosomes.
Asunto(s)
Esclerosis Amiotrófica Lateral/genética , Expansión de las Repeticiones de ADN/genética , Predisposición Genética a la Enfermedad/genética , Proteínas/genética , África/etnología , Anciano , Anciano de 80 o más Años , Esclerosis Amiotrófica Lateral/etnología , Pueblo Asiatico/genética , Proteína C9orf72 , China/etnología , Análisis Mutacional de ADN , Etnicidad/genética , Europa (Continente)/etnología , Femenino , Frecuencia de los Genes , Predisposición Genética a la Enfermedad/etnología , Haplotipos , Heterocigoto , Humanos , Japón/etnología , Estimación de Kaplan-Meier , Masculino , Mutación , Polimorfismo de Nucleótido Simple , EspañaRESUMEN
Non-invasive prenatal testing (NIPT) is currently the best screening test for fetal chromosome abnormalities with the highest sensitivity and specificity and can be done from 10 weeks gestation. We report a detection of 44.7 Mb duplication at 11p15.5-p11.2 by NIPT with a fetal fraction (FF) of only 3%. This chromosome abnormality was confirmed after amniocentesis by karyotyping and array comparative genomic hybridization (aCGH) on cultured fetal cells. Further parental investigation showed that the fetal chromosome abnormality was inherited from the mother who was a carrier of a balanced translocation 46,XX,t(11;X)(p11.2;q28). This case highlights the importance of expanded NIPT in the detection of fetal segmental aneuploidy. NIPT together with complementary studies can lead to the detection of parental chromosome rearrangement despite a low FF, which can impact the couple's reproductive plans. We also reviewed other cases with chromosome rearrangement, detected by NIPT, derived from a parental reciprocal translocation.