A new study clearly shows that this is a human female with multiple rare mutations in the genes that control bone formation. The research was published in the journal Genome Research, and led by Garry P. Nolan, the Rachford and Carlota A. Harris Professor in the department of microbiology and immunology at Stanford University School of Medicine. Nolan also conducted the 2013 analysis, with colleagues.
"The timeline starts about 50 years ago, which is when we think she died," said study coauthor Dr. Atul Butte, the Priscilla Chan and Mark Zuckerberg Distinguished Professor at the University of California San Francisco School of Medicine.
The DNA sample was somewhat degraded, but not as degraded as truly ancient samples. "This is not like one of those Ice Age samples, it’s more recent," Butte told BuzzFeed News.
An analysis of the mitochondrial DNA, which is inherited only from the mother, suggested she was of Chilean ancestry.
And the DNA mutations are "one-of-a-kind" and "super rare," Butte said. "A whole bunch of these genes are already known to be involved in bone growth and how bones grow and mature and these are new defects, new mutations, that people hadn’t seen before," he said.
The researchers checked for the gene mutations in tens of thousands of known recorded DNA sequences, but didn't find anyone else who had them. "Is there someone else on planet Earth who could have one of these? Could be, you never know until you go look," Butte said.
And it's clear that these are not the remains of a much older child with some type of dwarfism or other genetic changes that stunted growth. "This body, the baby, has a bone-age somewhere between 4 and 6 years of age, but we don’t think that the baby lived that long," said Butte. Instead, the gene mutations were likely causing the bones to age prematurely.
“What we think is probably this baby was still in utero, maybe this was a miscarriage or was not born or was stillborn and had the bone defects that led to the unusual skull and led to the bones growing like this," he said "Or maybe the miscarriage happened because all of these defects."
"It’s a sad story," said Butte. "This is a human girl — there’s a tragedy involved here."
However, the researchers hope the findings can lead to better recognition and understanding of bone growth abnormalities, possibly leading to better treatments for children who have such problems.