Skeletal dysplasias of the fetus and infant: comprehensive review and our experience over a 10-year period.

We present a comprehensive review dealing with rare genetic skeletal disorders. More than 400 entities are included in the latest classification. The most severe or lethal phenotypes are identifiable in the prenatal period and the pregnancy can be terminated. Perinatal autopsy and posmortem X-rays are crucial in providing a definitive diagnosis. The number of cases confirmed by genetic testing is increasing. We report our own experience with genetic skeletal disorders based on 41 illustrative fetal and neonatal cases which we encountered over a 10-year period. Thanatophoric dysplasia and osteogenesis imperfecta represent approximately half of the cases coming to autopsy. Achondrogenesis type 2 and hypochondrogenesis, short-rib dysplasia, chondrodysplasia punctata, campomelic dysplasia and achondroplasia are less common. Skeletal dysplasias with autosomal recessive inheritance are the least frequent, e.g. perinatally lethal hypophophatasia, achondrogenesis type 1A, diastrophic dysplasia/atelosteogenesis type 2 or mucolipidosis type 2 (I cell disease).

Noonan syndrome from a fetopathologist perspective.

We present our experience with four cases of fetal autopsies with abnormal prenatal ultrasound findings and suspicion of Noonan syndrome. These were fetuses from the 17th to the 24th age of gestation (GA). In all cases, prenatal ultrasound examination recorded increased nuchal translucency (NT) and presence of lymphatic neck sacs. Some fetuses showed signs of fetal hydrops and polyhydramnion was found. Similar signs and congenital developmental defects were confirmed in the autopsy examination. These were primarily signs of developing fetal hydrops with increased nuchal edema, in some cases up to the character of cystic hygroma, pleural and abdominal effusions, congenital heart and kidney defects, skeletal defects and facial dysmorphism. A karyotype was examined in all cases without chromosome aneuploidy. The diagnosis of NS was confimed by subsequent genetic analysis of causal gene mutations (mainly PTPN11, KRAS, RAF 1,). Our cases demonstrate a wide range of signs of prenatal presentation of this syndrome. Because of wide differential diagnosis, summarizing prenatal ultrasound findings, autopsy examination and molecular genetic testing is essential.