Skeletal dysplasias detectable by DNA analysis

Nuchal Translucency and Ductus venosus Blood Flow as Early Sonographic Markers of Thanatophoric Dysplasia

Thanatophoric dysplasia (TD) is the most frequent form of lethal osteochondrodysplasias. Prenatal diagnosis is commonly accomplished in the second-trimester scan, but occasionally TD may not be clearly distinguished from the other osteochondrodysplasias, with consequent important prognostic implications. However, in order to confirm the diagnosis, complementary radiological, pathological and molecular studies are mandatory. We present a case of TD diagnosed in the late first trimester with the contribution of nuchal translucency combined with ductus venosus blood flow assessment.

Three-dimensional ultrasound evaluation of short-rib polydactyly syndrome type II in the second trimester: a case report

Prenatal diagnosis of short-rib polydactyly syndrome is possible and has been reported in literature, but a precise ultrasound diagnosis is not easy. We report a case in which three-dimensional ultrasound was used in the evaluation of the disorder. The contribution and potential application of three-dimensional sonography in the prenatal diagnosis of short-rib polydactyly syndrome and other fetal skeletal malformations is discussed.

Diagnosis of skeletal dysplasia by multidisciplinary assessment: a report of two cases of thanatophoric dysplasia

Skeletal dysplasias, a heterogeneous group of bone growth disorders, can be detected by routine prenatal ultrasound examination. As it is difficult to make a specific diagnosis, prediction of prognosis is of importance for obstetric management. In order to specify diagnosis, radiological, pathological and molecular genetic examination are often required. Our report describes two cases of thanatophoric dysplasia with different fetal sonographic findings. The classical classification of type I and II seems to be ambiguous as, in both cases, the same mutation in the fibroblast growth factor receptor 3 gene was found. The importance of comprehensive multidisciplinary assessment is emphasized.

Skeletal anomalies

It is possible to identify many types of skeletal dysplasias and conditions involving limb deformities prenatally using ultrasound. It is likely that in the future, with the advancing technology and discoveries in molecular genetics, specific mutation analysis will become available for many of these conditions. This will make first trimester diagnosis an option in many cases. Because of the complex nature of many of these cases, it may be helpful to use a multidisciplinary approach involving a radiologist and a geneticist at times. In utero radiographs may help clarify a diagnosis. In lethal cases where a specific diagnosis has not been confirmed, it may be helpful postpartum to obtain an autopsy; photographs; complete body radiographs; karyotypic analysis; and specimens of bone, cartilage, and fetal blood for further analysis.

Prenatal diagnosis in congenital contractural arachnodactyly

Congenital contractural arachnodactyly (CCA) is a heritable connective tissue disorder caused by defects in the gene encoding fibrillin-2 (FBN2). People with CCA typically have a marfanoid habitus, flexion contractures, severe kyphoscoliosis, abnormal pinnae, and muscular hypoplasia. Because of the relative infrequency of the syndrome and its generally mild to moderate severity, prenatal diagnosis had not previously been sought. Here we report prenatal diagnosis in a family with CCA. Because the course of the disease in the proband was rather severe, she had requested genetic counseling as early as age 17. She delayed childbearing until prenatal diagnosis for CCA became possible. This decision was supported by her mother and later her husband. Because she shared the same genotype with her husband, genetic linkage analysis of this family did not alter the a priori 50% risk of having an affected child. The possibility of unambiguously ascertaining the affected status of a fetus homozygous for the tested FBN2 marker was sufficient for the family to pursue prenatal diagnosis. This case strongly points to the importance of informed decisions now that genetic testing is becoming commonplace.

Craniosynostosis associated with FGFR3 pro250arg mutation results in a range of clinical presentations including unisutural sporadic craniosynostosis

Several mutations involving the fibroblast growth factor receptor (FGFR) gene family have been identified in association with phenotypically distinct forms of craniosynostosis. One such point mutation, resulting in the substitution of proline by arginine in a critical region of the linker region between the first and second immunoglobulin-like domains, is associated with highly specific phenotypic consequences in that mutation at this point in FGFR1 results in Pfeiffer syndrome and analogous mutation in FGFR2 results in Apert syndrome. We now show that a much more variable clinical presentation accompanies analogous mutation in the FGFR3 gene. Specifically, mental retardation, apparently unrelated to the management of the craniosynostosis, appears to be a variable clinical consequence of this FGFR3 mutation.