P07.03: Prenatally diagnosed tracheal atresia in twin pregnancy

Abstract

Cardiofaciocutaneous (CFC) syndrome is a rare genetic disease characterized by congenital heart diseases, dysmorphic craniofacial features and ectodermal abnormalities. It is due to mutation in the BRAF, MAP2K1, MAP2K2 or KRAS gene. So far all the cases have been of sporadic occurrence due to de novo dominant mutations. Therefore, prenatal diagnosis relies on ultrasound suspicion followed by genetic confirmation. Prenatal ultrasound findings, including increased nuchal translucency (NT) or cystic hygroma in the first trimester and mild pyelectasis, mild ventriculomegaly, macrosomia, relatively short femur and polyhydramnios in the second trimester, have only been described retrospectively after postnatal diagnosis. We describe the prenatal ultrasound features of a prenatally diagnosed case of CFC due to heterozygous mutation in the BRAF gene. A huge NT of 9.5 mm was found with normal karyotype and array CGH study. Ultrasound examination at 18 weeks showed macrocephaly and macrosomia with an average femur length, thick nuchal fold with distended jugular lymphatic sacs, cerebellar vermian hypoplasia and bilateral mild pyelectasis. Three-dimensional (3D) study of the fetal face showed laterally downward slanting palpebral fissures, low set posteriorly rotated ears and broad nose with bulbous nasal tip. Being prenatally diagnosed, our case allowed a more thorough ultrasound examination, including 3D study, of the fetus and thus a more detailed description of the prenatal features of CFC. Increased NT or cystic hygroma in the first trimester and macrosomia, macrocephaly, pyelectasis, brain abnormalities and polyhydramnios in the second trimester seem to be common prenatal findings in CFC. Hopefully more cases reported in future will allow determination of a set of prenatal ultrasound features specific to CFC. As CFC is phenotypically similar to Noonan and Costello syndrome, simultaneous genetic testing for these closely related syndromes may improve the diagnostic yield. We present a rare case of prenatally diagnosed tracheal atresia in one of the fetuses of twin pregnancy. During routine 2nd trimester scan of otherwise normal dichorionic twin pregnancy, bilateral and uniform hyperechogenicity of fetal thorax, ascites, pulmonary hyperplasia, diaphragmatic eversion, mediastinal compression with large heart vessels, hydrops and polyhydramnios in one of the fetuses were noted leading us to working diagnosis of laryngeal atresia. Later an increase of ascites was observed and affected fetus died in utero at 31 weeks. The second twin was developing well and delivered by CS at 34 weeks (boy, 1700 g) due to spontaneous onset of delivery. The affected fetus (girl, 1440 g) was on autopsy diagnosed with tracheomalacia and tracheal atresia just above the level of anticipated branching into the bronchi. P07.03 Prenatally diagnosed tracheal atresia in twin pregnancyTracheal atresia and other types of breathing tubes occlusion are very rare birth defects. About 50-90% of all cases are associated with other fatal congenital defects....