Performance and Diagnostic Value of Genome-Wide Noninvasive Prenatal Testing in Multiple Gestations.

OBJECTIVE: To evaluate the accuracy and diagnostic value of genome-wide noninvasive prenatal testing (NIPT) for the detection of fetal aneuploidies in multiple gestations, with a focus on dichorionic-diamniotic twin pregnancies. METHODS: We performed a retrospective cohort study including data from pregnant women with a twin or higher-order gestation who underwent genome-wide NIPT at one of the eight Belgian genetic centers between November 1, 2013, and March 1, 2020. Chorionicity and amnionicity were determined by ultrasonography. Follow-up invasive testing was carried out in the event of positive NIPT results. Sensitivity and specificity were calculated for the detection of trisomy 21, 18, and 13 in the dichorionic-diamniotic twin cohort. RESULTS: Unique NIPT analyses were performed for 4,150 pregnant women with a multiple gestation and an additional 767 with vanishing gestations. The failure rate in multiple gestations excluding vanishing gestations ranged from 0% to 11.7% among the different genetic centers. Overall, the failure rate was 4.8%, which could be reduced to 1.2% after single resampling. There were no common fetal trisomies detected among the 86 monochorionic-monoamniotic and 25 triplet cases. Two monochorionic-diamniotic twins had an NIPT result indicative of a trisomy 21, which was confirmed in both fetuses. Among 2,716 dichorionic-diamniotic twin gestations, a sensitivity of 100% (95% CI 74.12-100%) and a specificity of 100% (95% CI 99.86-100%) was reached for trisomy 21 (n=12). For trisomy 18 (n=3), the respective values were 75% (95% CI 30.06-95.44%) sensitivity and 100% (95% CI 99.86-100%) specificity, and for trisomy 13 (n=2), 100% (95% CI 20.65-100%) sensitivity and 99.96% (95% CI 99.79-99.99%) specificity. In the vanishing gestation group, 28 NIPT results were positive for trisomy 21, 18, or 13, with only five confirmed trisomies. CONCLUSION: Genome-wide NIPT performed accurately for detection of aneuploidy in dichorionic-diamniotic twin gestations

Identification of intellectual disability genes in female patients with skewed X-inactivation.

status: publishe

Expanding the phenotypic spectrum of PORCN variants in two males with syndromic microphthalmia

Variants in PORCN are a cause of Goltz-Gorlin syndrome or Focal Dermal Hypoplasia, an X-linked dominant disorder affecting heterozygous females and until now considered to be embryonic lethal in males. Exome sequencing was performed in a family in which two male siblings were characterized by microphthalmia and additional congenital anomalies including diaphragmatic hernia, spina bifida and cardiac defects. Surprisingly, we identified a maternally inherited variant in PORCN present in both males as well as in two female siblings. This represents the first finding of a PORCN variant in non-mosaic males affected with Goltz-Gorlin syndrome. The apparently asymptomatic mother showed extreme skewing of X-inactivation (90%), an asymptomatic female sibling showed skewing of 88%, and the second female sibling affected with cutis aplasia of the scalp showed X-inactivation considered within the normal range.European Journal of Human Genetics advance online publication, 16 July 2014; doi:10.1038/ejhg.2014.135.status: publishe

Microdeletion of the escape genes KDM5C and IQSEC2 in a girl with severe intellectual disability and autistic features

Intellectual disability (ID) is a very heterogeneous disorder with over 100 ID genes located on the X chromosome alone. Of these, KDM5C and IQSEC2 are located adjacent to each other at the Xp11.22 locus. While mutations in either of these genes are associated with severe ID in males, female carriers are mostly unaffected. Here, we report on a female patient with severe ID and autistic features carrying a de novo 0.4 Mb deletion containing six coding genes including KDM5C and IQSEC2. X-inactivation analysis revealed skewing in a lymphocyte-derived cell line from this patient with preferential inactivation of the mutant X chromosome. As the brain-expressed KDM5C and IQSEC2 genes escape X-inactivation, deletion of these alleles could still be detrimental despite skewing of X-inactivation. Indeed, mutations in either of both genes have been reported in a few female ID patients. Expression analysis in the patients' cell line revealed decreased KDM5C mRNA levels compared to female controls. IQSEC2 levels could not be compared due to very low expression in blood. Overall, our data suggest that heterozygous loss-of-function of the escape genes KDM5C and/or IQSEC2 can contribute to severe ID in female patients and should be taken into account in diagnostics.publisher: Elsevier articletitle: Microdeletion of the escape genes KDM5C and IQSEC2 in a girl with severe intellectual disability and autistic features journaltitle: European Journal of Medical Genetics articlelink: http://dx.doi.org/10.1016/j.ejmg.2015.03.003 content_type: article copyright: Copyright © 2015 Elsevier Masson SAS. All rights reserved.status: publishe

Early Frameshift Mutation in PIGA Identified in a Large XLID Family Without Neonatal Lethality

The phosphatidylinositol glycan class A (PIGA) protein is a member of the glycosylphosphatidylinositol (GPI) anchor pathway. Germline mutations in PIGA located at Xp22.2 are thought to be lethal in males. However, a nonsense mutation in the last coding exon was recently described in two brothers with multiple congenital anomalies-hypotonia-seizures syndrome 2 (MCAHS2) who survived through birth likely due to the hypomorphic nature of the truncated protein, but died in their first weeks of life. Here, we report on a frameshift mutation early in the PIGA cDNA (c.76dupT; p.Y26Lfs*3) that co-segregates with the disease in a large family diagnosed with a severe syndromic form of X-linked intellectual disability (XLID). Unexpectedly, CD59 surface expression suggested the production of a shorter PIGA protein with residual functionality. We provide evidence that the second methionine at position 37 may be used for the translation of a 36 amino acids shorter PIGA. Complementation assays confirmed that this shorter PIGA cDNA was able to partially rescue the surface expression of CD59 in a PIGA-null cell line. Taken together, our data strongly suggest that the early frameshift mutation in PIGA produces a truncated hypomorph, which is sufficient to rescue the lethality in males but not the MCAHS2-like phenotype. This article is protected by copyright. All rights reserved.status: publishe

Belgische en Nederlandse stadsgeschiedenis in historische tijdschriften (2020)

Cities, Migration and Global Interdependenc