Homozygous null variant in CRADD, encoding an adaptor protein that mediates apoptosis, is associated with lissencephaly

Am J Med Genet A. 2017 Sep;173(9):2539-2544. doi: 10.1002/ajmg.a.38347. Epub 2017 Jul 7.

Abstract

Lissencephaly is a severe malformation of cortical development, most often attributed to abnormalities in neuronal migration. It is associated with a severe prognosis including developmental delay, intellectual disability, and seizures. Lissencephaly can be reliably diagnosed during late gestation by neurosonography or fetal magnetic resonance imaging (MRI). We report two sibling male fetuses who were diagnosed with delayed cortical sulcation highly suggestive of lissencephaly during late pregnancy. After receiving genetic counseling, the parents elected to terminate the pregnancies based on the neuroradiological findings and the associated severe prognosis. Whole exome sequencing (WES) of an affected fetus, and subsequent Sanger sequencing of the second fetus, revealed a homozygous frameshift variant in CRADD, which encodes an adaptor protein that interacts with PIDD and caspase-2 to initiate apoptosis. Biallelic variants in this gene have been recently reported to cause "thin" lissencephaly and intellectual disability. Interestingly, the allegedly healthy father was also found to be homozygous for the variant, prompting evaluation by brain MRI which revealed hypogyration. This study underscores the phenotypic variability of pathogenic variants in CRADD and the challenges of prenatal genetic counseling.

Keywords: CRADD; intellectual disability; lissencephaly; prenatal diagnosis.

Publication types

  • Case Reports

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Apoptosis / genetics*
  • CRADD Signaling Adaptor Protein / genetics*
  • Caspase 2 / genetics
  • Death Domain Receptor Signaling Adaptor Proteins / genetics*
  • Exome / genetics
  • Female
  • Fetus / diagnostic imaging
  • Fetus / physiopathology
  • Genetic Counseling
  • Homozygote
  • Humans
  • Lissencephaly / genetics*
  • Lissencephaly / physiopathology
  • Magnetic Resonance Imaging
  • Male
  • Pregnancy
  • Prenatal Diagnosis

Substances

  • Adaptor Proteins, Signal Transducing
  • CRADD Signaling Adaptor Protein
  • CRADD protein, human
  • Death Domain Receptor Signaling Adaptor Proteins
  • PIDD1 protein, human
  • Caspase 2