[Application of high-throughput sequencing technology for the detection of fetal copy number variations].

OBJECTIVE: To assess the value of non-invasive prenatal testing (NIPT) for the detection of fetal copy number variations (CNVs) in addition to trisomies 21, 18, and 13. METHODS: A total of 37 306 pregnant women underwent the NIPT test. For those with fetal CNVs indicated by NIPT and accepted invasive prenatal diagnosis, amniotic fluid samples were obtained for chromosomal karyotyping analysis and chromosome microarray analysis (CMA). All cases were followed up. RESULTS: Among the 37 306 cases, 78 (0.209%) were predicted to have fetal CNVs. Among these, 52 pregnant women accepted invasive prenatal diagnosis, and 15 of them (28.85%) obtained a consistent result. Follow up of 26 women who refused invasive prenatal diagnosis have found 2 cases with spontaneous abortion, 2 with induced labor for fetal malformation indicated by ultrasonography, and 1 had multiple malformations and a consistent result by CMA, which yielded an abnormal rate of 19.23%. CONCLUSION: NIPT can signal fetal chromosomal abnormalities through detection of gain and/or loss of fetal DNA copies. Combined chromosomal karyotyping and CMA can increase the detection rate for common chromosomal aneuploidies and CNVs, thereby provide a basis for genetic counseling for the affected families.

S113R mutation in SLC33A1 leads to neurodegeneration and augmented BMP signaling in a mouse model.

The S113R mutation (c.339T>G) (MIM #603690.0001) in SLC33A1 (MIM #603690), an ER membrane acetyl-CoA transporter, has been previously identified in individuals with hereditary spastic paraplegia type 42 (SPG42; MIM #612539). SLC33A1 has also been shown to inhibit the bone morphogenetic protein (BMP) signaling pathway in zebrafish. To better understand the function of SLC33A1, we generated and characterized Slc33a1S113R knock-in mice. Homozygous Slc33a1S113R mutant mice were embryonic lethal, whereas heterozygous Slc33a1 mutant mice (Slc33a1wt/mut) exhibited behavioral abnormalities and central neurodegeneration, which is consistent with hereditary spastic paraplegia (HSP) phenotypes. Importantly, we found an upregulation of BMP signaling in the nervous system and mouse embryonic fibroblasts of Slc33a1wt/mut mice. Using a sciatic nerve crush injury model in vivo and dorsal root ganglion (DRG) culture in vitro we showed that injury-induced axonal regeneration in Slc33a1wt/mut mice was accelerated and mediated by upregulated BMP signaling. Exogenous addition of BMP signaling antagonist, noggin, could efficiently alleviate the accelerated injury-induced axonal regrowth. These results indicate that SLC33A1 can negatively regulate BMP signaling in mice, further supporting the notion that upregulation of BMP signaling is a common mechanism of a subset of hereditary spastic paraplegias.