OBJECTIVE: To present the fetal features of Cornelia de Lange Syndrome (CdLS) with a molecular confirmation.
METHODS: This was a retrospective study of 13 cases with CdLS diagnosed by prenatal and postnatal genetic testing and physical examination. Clinical and laboratory data were collected and reviewed for these cases, including maternal demographics, prenatal sonographic findings, chromosomal microarray and exome sequencing (ES) results, and pregnancy outcomes.
RESULTS: All of the 13 cases were detected to have a CdLS-causing variant, with 8 variants identified in the NIPBL gene, 3 in SMC1A, and 2 in HDAC8. Five had normal ultrasound scans during pregnancy; all were caused by variants of SMC1A or HDAC8. For the eight cases with NIPBL variants, all had prenatal ultrasound markers. Three had first trimester ultrasound markers including increased nuchal translucency in one and limb defects in three. Four presented with normal ultrasound in the first trimester, but abnormal ultrasound in the second trimester, including micrognathia in two, hypospadias in one and intrauterine growth retardation (IUGR) in one. IUGR as the isolated feature was identified in one case in the third trimester.
CONCLUSIONS: The prenatal diagnosis of CdLS caused by NIPBLvariants is possible. It seems to remain challenging to detect non-classic CdLS only relying on ultrasound examination.

Background: Aplasia cutis congenita (ACC) and terminal transverse limb defects (TTLDs) are the most common features of Adams-Oliver syndrome (AOS). ARHGAP31 is one of the causative genes for autosomal dominant forms of AOS, meanwhile its variants may only cause isolated TTLD. Here, we report a proband presented with apparent TTLD but not ACC. Methods: Whole exome sequencing (WES) and Sanger sequencing were applied to identify causative genes. Expression vectors were constructed for transfections in mammalian cell cultures followed by biochemical and functional analysis including immunoblotting, immunofluorescence staining, and cell counting kit-8 assay. Results: WES and Sanger sequencing suggested that the proband inherited rare ARHGAP31 variant [c.2623G > A (p.Glu875Lys)] and a rare FBLN1 variant [c.1649G > A (p.Arg550His)] from one of her asymptomatic parents, respectively. Given FBLN1 variation has also been linked to syndactyly, we suspected that the two genes together contributed to the TTLD phenotype and explored their possible roles in vitro. Mutant FBLN1 showed reduced expression resulted from impaired protein stability, whereas ARHGAP31 protein expression was unaltered by mutation. Functional assays showed that only in the co-transfected group of two mutants cell viability was decreased, cell proliferation was impaired, and apoptosis was activated. Cdc42 activity was declined by both ARHGAP31 mutation and FBLN1 mutation alone, and the two together. Furthermore, the MAPK/ERK pathway was only activated by two mutants co-transfected group compared with two wild-type transfections. Conclusion: We report a case carrying two rare variants of limb defects associated genes, ARHGAP31 and FBLN1, and provide in vitro evidence that synergistic disruption of cellular functions attributed by the two mutants may potentiate the penetrance of clinical manifestations, expanding our knowledge of clinical complexity of causal gene interactions in TTLD and other genetic disorders.

BACKGROUND: Air pollution influences the development of limb defects in animals. There is little epidemiologic evidence on the effect of prenatal air pollution exposure on the risk of limb defects.
OBJECTIVE: To assess the relations between exposure to ambient air pollutants and the risk of limb defects.
METHODS: We conducted a matched-pairs case-control study in Taiwan from 2001 through 2007. The case group consisted of 1687 limb defects and the control group was density-sampling matched one to ten based on the month and year of conception from 1510,064 live singleton newborns in 2001-2007. Adjusted conditional logistic regression models were used to estimate odds ratios per 10 ppb change for O3, NO2, 1 ppb change for SO2, 10 µg/m(3) change for PM10, and 100 ppb change for CO during the first trimester and first three gestational months.
RESULTS: Of the specific limb defects, reduction deformities of limbs (adjusted OR=1.024, 95% CI: 1.000, 1.048) was associated with a 1 ppb increase in SO2 during weeks of 9-12 of gestation as well as the first trimester. Reduction deformities of limbs was also associated with a 10 ppb increase in O3 during weeks of 1-4 of gestation (adjusted OR=1.391, 95% CI: 1.064, 1.818) among preterm births.
CONCLUSIONS: The present study provides evidence that exposure to outdoor air SO2 during the first trimester of pregnancy may increase the risk of limb defects. Exposure to O3 was associated with reduction deformities of limbs among preterm births. Similar levels of SO2 and O3 are encountered globally by large numbers of pregnant women.