Skeletal dysplasias: 38 prenatal cases

To assess the prenatal diagnosis of skeletal dysplasias in a single center over a ten-years period.

All antenatal detected skeletal dysplasias during the period January 1st 1996 until December 31 2005 (10 years) were retrieved from the genetic database. This database includes all skeletal dysplasias where invasive prenatal diagnosis (chorionic villus sampling/amniocentesis) was performed. The final diagnosis was sought on the basis of fetopathological examination, radiographic studies and if possible molecular testing.

A total of 46 antenatal skeletal dysplasias were diagnosed during this period. Follow-up was only available in 38 cases. The other 8 cases involved prenatally presumed lethal skeletal dysplasias that were interrupted in the referral hospital with no further information sent to us. The mean gestational age at diagnosis was 23 weeks (range 12-33 weeks). A diagnosis < or = 24 weeks was made in 25 cases (65.8%). Eleven skeletal dysplasias were diagnosed > 30 weeks (29%) and these included all achondroplasias (n = 6), hypophosphatasia (n = 1), Jeune syndrome (n = 1), osteogenesis imperfecta type II (n = l), type I (n = 1) and type III (n = 1). In 27 cases a lethal skeletal dysplasia was present (71%) and these were all correctly predicted. Of the lethal skeletal dysplasias 5 cases were diagnosed only after 24 weeks of pregnancy (19%) and 3 were only referred after 30 weeks (11.5%). A final diagnosis was obtained in 36 cases by fetopathological examination and radiographic studies and molecular testing as deemed necessary. Specific diagnoses included: achondroplasia (n = 6), achondrogenesis (n = 2), osteogenesis imperfecta type II (n = 9), osteogenesis imperfecta type I (n = 1), osteogenesis imperfecta type III (n = 1), thanatophoric dysplasia (n = 7), hypophosphatasia (n = 1), Majewski syndrome (n = 11), Mohr-Majewski syndrome (n = 11), Jeune syndrome (n = 2), Ellis-van Creveld syndrome (n = 2), Roberts syndrome (n = 1), campomelic dysplasia (n = 2). In two cases postnatal investigation revealed no certain diagnosis and these included one patient with symmetrical tetraphocomelia with aspects of Roberts and Femur-fibula-Ulna syndrome and one patient at 15 weeks with a lethal skeletal dysplasia with rhizomelic limb shortening, a narrow thorax, platyspondyly, normocephaly, a normal pelvis, and a posterior cleft palate. A correct antenatal diagnosis was made in 25 cases (65.8%) including osteogenesis imperfecta type II (n = 9), thanatophoric dysplasia (n = 7), achondroplasia (n = 6), achondrogenesis (n = 2) and Roberts syndrome (n = 1).

The antenatal prediction of lethality in this series of prenatal diagnosed skeletal dysplasias was correct. A correct antenatal diagnosis of the type of skeletal dysplasia was difficult, with 25 of 38 cases correctly diagnosed.