Prenatal diagnosis and post-mortem examination in a fetus with thrombocytopenia-absent radius (TAR) syndrome due to compound heterozygosity for a 1q21.1 microdeletion and a RBM8A hypomorphic allele: a case report

BMC Res Notes. 2013 Sep 22:6:376. doi: 10.1186/1756-0500-6-376.


Background: Thrombocytopenia-absent radius syndrome is a rare autosomal recessive disorder characterized by megakaryocytic thrombocytopenia and longitudinal limb deficiencies mostly affecting the radial ray. Most patients are compound heterozygotes for a 200 kb interstitial microdeletion in 1q21.1 and a hypomorphic allele in RBM8A, mapping in the deleted segment. At the moment, the complete molecular characterization of thrombocytopenia-absent radius syndrome is limited to a handful of patients mostly ascertained in the pediatric age

Case presentation: We report on a fetus with bilateral upper limb deficiency found at standard prenatal ultrasound examination. The fetus had bilateral radial agenesis and humeral hypo/aplasia with intact thumbs, micrognathia and urinary anomalies, indicating thrombocytopenia-absent radius syndrome. Molecular studies demonstrated compound heterozygosity for the 1q21.1 microdeletion and the RBM8A rs139428292 variant at the hemizygous state, inherited from the mother and father, respectively

Conclusion: The molecular information allowed prenatal diagnosis in the following pregnancy resulting in the birth of a healthy carrier female. A review was carried out with the attempt to the trace the fetal ultrasound presentation of thrombocytopenia-absent radius syndrome and discussing opportunities for second-tier molecular studies within a multidisciplinary setting.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abnormalities, Multiple / diagnostic imaging
  • Abnormalities, Multiple / genetics*
  • Abnormalities, Multiple / pathology
  • Adult
  • Alleles*
  • Autopsy
  • Chromosome Deletion
  • Chromosomes, Human, Pair 1 / diagnostic imaging
  • Chromosomes, Human, Pair 1 / genetics
  • Comparative Genomic Hybridization
  • Congenital Bone Marrow Failure Syndromes
  • Fatal Outcome
  • Female
  • Fetus / metabolism
  • Fetus / pathology*
  • Heterozygote*
  • Humans
  • Male
  • Megalencephaly / diagnostic imaging
  • Megalencephaly / genetics*
  • Megalencephaly / pathology
  • Pedigree
  • Pregnancy
  • Prenatal Diagnosis*
  • RNA-Binding Proteins / genetics*
  • Radiography
  • Radius / diagnostic imaging
  • Radius / pathology
  • Syndrome
  • Thrombocytopenia / diagnostic imaging
  • Thrombocytopenia / genetics*
  • Thrombocytopenia / pathology
  • Upper Extremity Deformities, Congenital / diagnostic imaging
  • Upper Extremity Deformities, Congenital / genetics*
  • Upper Extremity Deformities, Congenital / pathology


  • RBM8A protein, human
  • RNA-Binding Proteins

Supplementary concepts

  • Absent radii and thrombocytopenia
  • Chromosome 1q21.1 Deletion Syndrome, 1.35-Mb