RESUMEN
Here, we report a previously unrecognized syndromic neurodevelopmental disorder associated with biallelic loss-of-function variants in the RBM42 gene. The patient is a 2-year-old female with severe central nervous system (CNS) abnormalities, hypotonia, hearing loss, congenital heart defects, and dysmorphic facial features. Familial whole-exome sequencing (WES) reveals that the patient has two compound heterozygous variants, c.304C>T (p.R102*) and c.1312G>A (p.A438T), in the RBM42 gene which encodes an integral component of splicing complex in the RNA-binding motif protein family. The p.A438T variant is in the RRM domain which impairs RBM42 protein stability in vivo. Additionally, p.A438T disrupts the interaction of RBM42 with hnRNP K, which is the causative gene for Au-Kline syndrome with overlapping disease characteristics seen in the index patient. The human R102* or A438T mutant protein failed to fully rescue the growth defects of RBM42 ortholog knockout ΔFgRbp1 in Fusarium while it was rescued by the wild-type (WT) human RBM42. A mouse model carrying Rbm42 compound heterozygous variants, c.280C>T (p.Q94*) and c.1306_1308delinsACA (p.A436T), demonstrated gross fetal developmental defects and most of the double mutant animals died by E13.5. RNA-seq data confirmed that Rbm42 was involved in neurological and myocardial functions with an essential role in alternative splicing (AS). Overall, we present clinical, genetic, and functional data to demonstrate that defects in RBM42 constitute the underlying etiology of a new neurodevelopmental disease which links the dysregulation of global AS to abnormal embryonic development.
Asunto(s)
Femenino , Animales , Ratones , Humanos , Preescolar , Discapacidad Intelectual/genética , Cardiopatías Congénitas/genética , Facies , Fisura del Paladar , Hipotonía MuscularRESUMEN
BACKGROUND: Noninvasive prenatal testing (NIPT) has been widely used clinically to detect fetal chromosomal aneuploidy with high accuracy rates, gradually replacing traditional serological screening. However, the application of NIPT for monogenic diseases is still in an immature stage of exploration. The detection of mutations in peripheral blood of pregnant women requires precise qualitative and quantitative techniques, which limits its application. The bioinformatic strategies based on the SNP (single nucleotide polymorphism) linkage analysis are more practical, which can be divided into two types depending on whether proband information is needed. Hidden Markov Mode (HMM) and Sequential probability ratio test (SPRT) are suitable for families with probands. In contrast, methods based on databases and population demographic information are suitable for families without probands. METHODS: In this study, we proposed a Spearman rank correlation analysis method to infer the fetal haplotypes based on core family information. Allele frequencies of SNPs that were used to construct parental haplotypes were calculated as sets of nonparametric variables, in contrast to their theoretical values represented by a fetal fraction (FF). The effects on the calculation of the fetal concentration of two DNA enrichment methods, multiple-PCR amplification, and targeted hybrid capture, were compared, and the heterozygosity distribution of SNPs within pedigrees was analyzed to reveal the best conditions for the model application. RESULTS: Predictions of the paternal haplotype inheritance were in line with expectations for both DNA library construction methods, while for maternal haplotype inheritance prediction, the rates were 96.55% for method multiple-PCR amplification and 95.8% for method targeted hybrid capture. CONCLUSION: Positive prediction rates showed that the maternal haplotype prediction was not as accurate as paternal one, due to the large amount of maternal noise in the mother's peripheral blood. Although this model is relatively immature, it provides a new perspective for noninvasive prenatal clinical tests of monogenic diseases.
Asunto(s)
Pruebas Prenatales no Invasivas , Diagnóstico Prenatal , Femenino , Feto , Haplotipos , Humanos , Linaje , Embarazo , Diagnóstico Prenatal/métodosRESUMEN
OBJECTIVE@#To carry out prenatal diagnosis for families with high risk for spinal muscular atrophy (SMA) by using multiplex ligation-dependent probe amplification (MLPA).@*METHODS@#Twenty-one families were enrolled. MLPA was used to detect copy numbers of SMN1 and SMN2 genes. Maternal contamination was excluded by using a short tandem repeat method.@*RESULTS@#For 23 fetuses from the 21 families, 14 were identified as carriers, 1 as SMA patient, and 8 as normal. By linkage analysis of parental samples, three individuals were determined as silent (2+0) carriers.@*CONCLUSION@#MLPA can determine the carrier status of SMA. The identification of three silent (2+0) carriers among the 44 parental samples indicated a risk for such families, for which genetic counseling and reproduction guidance should be provided.