Tuesday 30 September 2003
Hydrops-ectopic calcification-"moth-eaten" (HEM) or Greenberg’s skeletal dysplasia is an autosomal recessive chondrodystrophy with a lethal course, characterized by fetal hydrops, short limbs, and abnormal chondro-osseous calcification.
Greenberg dysplasia. Greenberg dysplasia (MIM.215140), also called hydrops–ectopic calcification–moth-eaten skeletal dysplasia (HEM dysplasia), is a rare autosomal recessive skeletal dysplasia first described by Greenberg et al.
The phenotypic findings of this lethal disorder can include dysmorphic facial features, hydrops fetalis, cystic hygroma, incomplete lung lobation, pulmonary hypoplasia, extramedullary hematopoiesis, intestinal malrotation, polydactyly, and very short limbs.
Radiological findings include a distinctive “moth-eaten” appearance of the long bones, platyspondyly with abnormal ossification centers, ectopic ossification of both the ribs and the pelvis, and deficient ossification of the skull.
Histological characterization showed marked disorganization of cartilage and bone, with absence of cartilage column formation, nodular calcifications in cartilage, and islands of cartilage surrounded by bone.
3beta-hydroxysterol delta(14)-reductase deficiency due to mutations in the LBR gene coding for lamin B receptor gene.
Based on the observation that the ossification abnormalities found in HEM dysplasia are similar to the ossification abnormalities found in CDPX2, Kelley analyzed sterols from cartilage obtained from four fetuses with HEM dysplasia.
He found increased levels of cholesta-8,14-dien-3β-ol and cholesta-8,14,24-trien-3β-ol, consistent with a deficiency of 3β-hydroxysterol Δ14-reductase activity. To date, the genetic cause of HEM dysplasia has not been identified.
inborn errors of cholesterol synthesis
Malformation syndromes due to inborn errors of cholesterol synthesis. Forbes D. Porter. http://www.jci.org/articles/view/16386