Startling images in the journal Neurology made the media rounds last week. CT scans show a partial fetus wedged within a space (ventricle) in the brain of its one-year-old sister. In photos, the removed potential sibling resembles a pink tadpole.
The report, called a Teaching NeuroImage, is from four researchers at Beijing Tiantan Hospital, and entitled "Intraventricular Fetus-in-Fetu, With Extensive De Novo Gain in Genetic Copy Number." That means the genome of the doomed fetus-within-a-fetus had lots of copies of certain short DNA sequences that aren't in the parents' genomes ("de novo" means new).
With only two short paragraphs, the report doesn't explore the significance of the discovery of the repeat-riddled genome. But I thought immediately of young children with combinations of developmental delay, intellectual disability, autism, learning disabilities, and behavioral conditions that turn out to have microduplications or microdeletions – that is, bits of DNA copied too many times, or missing. Might the partial fetus have had an extreme version of the DNA repeats that are associated with these syndromes, halting development well before birth?
To continue reading, go to DNA Science, where this post first appeared.