Chilean Skeleton’s DNA Reveals Disease-Inducing Mutations

“Ata,” a mummified specimen from Atacama region of Chile. (Bhattacharya S et al. 2018)

(CN) – A 6-inch mummified humanoid skeleton found in Chile in 2003 with a bone age of 6 to 8 years at time of death has provoked speculation as to its origin. After whole genome sequencing of the skeleton, researchers offer insights into its ancestry and unusual physical characteristics.

The findings, published Thursday in the journal Genome Research, reveal that the specimen’s miniature stature and multiple skeletal irregularities – including its cone-shaped skull – could stem from a relatively short list of mutations in genes associated with diseases like scoliosis, dwarfism and musculoskeletal abnormalities.

“This was an unusual specimen with some fairly extraordinary claims put forward,” said senior author Garry Nolan, a professor of microbiology and immunology at Stanford University. “It would be an example of how to use modern science to answer the question, ‘What is it?’”

The team used DNA extracted from the specimen’s bone marrow to conduct a whole-genome sequence analysis.

Sequencing reads matched human and non-human primate reference genomes, including rhesus macaque and chimpanzee, which showed that the specimen, known as Ata, was of human origin. Ata’s Chilean ancestry was determined by comparing single-nucleotide polymorphisms against a database of known SNPs from a diverse range of geographical populations. The sequence read also revealed that the specimen was female.

The researchers then searched for genetic clues that could explain Ata’s exceptionally small stature, abnormal rib count, premature bone age and bone and skull abnormalities. This revealed the specimen’s “dramatic phenotype could in fact be explained with a relatively short list of mutations in genes known previously to be associated with bone development,” according to Nolan.

Future research using deeper sequencing and analyses of the novel sequence variations discovered in Ata may enhance our understanding of the functional basis of genetic skeletal disorders.

“This is a great example of how studying ancient samples can teach us how to analyze modern-day medical samples,” said co-author Atul Butte, director of the Institute for Computational Health Sciences at the University of California, San Francisco (UCSF).

The research was funded by Stanford, Stanford’s School of Medicine, UCSF, the National Autonomous University of Mexico, Roche Sequencing Solutions, and Ultra Intelligence Corporation.

Researchers believe Ata died about 40 years ago. Nolan told National Geographic that while no one knows anything about her parents, someone cared for her when she died: she was carefully laid out and wrapped in a leather pouch.

 

 

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