Dal’s being dug up for a paternity test. But is his DNA intact? – STAT

E

ven if you didnt take art history classes in school, you probably know Salvador Dals work. One of the surrealists most famous paintings, The Persistence of Memory, is the one with the melting clocks.

But memory is not the only thing that persists a woman who has claimed to be Dals daughter for over a decade has not given up. To support her contention, Pilar Abel has had two previous paternity tests performed one with inconclusive results, another that allegedly never sent her results. Now a Spanish court has granted her request to have Dals body exhumed from a crypt in Catalonia so a third test can be conducted.

But Dal has been dead for nearly 30 years. Can a sample of his DNA still give Abel a definitive answer?

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Yes and no, saidHendrik Poinar, principal investigator at the McMaster Ancient DNA Center in Ontario, Canada. The success of the test will depend on a lot of factors including, possibly, which kind of analysis is done.

Poinar isnt involved in the case, but he is trying to solve a mystery about another famous 20th-century artist. Hes analyzing the remains of poet and Nobel laureate Pablo Neruda to determine if a bacteria was involved in his death in 1973.

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The researchers working with Dals DNA will need to consider two main issues: contamination during the exhumation and working with degraded DNA afterward, Poinar said.

Though Dal died in 1989 certainly not ancient history your DNA degrades the minute you die, Poinar said. He and his students will often define ancient DNA as anything thats buried in the ground.

A sample will likely come from one of three places: hair, a molar tooth, or a small but very compact bone in the skull near the inner ear. Hair is pretty resistant to contamination, Poinar said, and the bone called thepetrous bone has the most DNA per gram of any part of the skeleton.

A standard forensics lab might take these samples, extract DNA, and look at a set of more than a dozen microsatellites, Poinar said. Each microsatellite can range from 100 to 400 DNA base pairs long and can vary in only so many ways in which DNA bases repeat and how many times they repeat. (These repeating sequences are called short tandem repeats, or STRs; looking for them is called STR analysis.)

For comparison, the human genome is about 3 billion base pairs long.The possible patterns are numerous enough that determining if two samples come from the same person or if the donor of one sample is likely related to the other is very possible.

However, Dals DNA may be in shorter fragments which may mean this DNA profiling technique will be less reliable. In Poinars experience, the average length of a DNA fragment from skeletal remains is about 70 to 80 base pairs so the average fragment would likely have only part of a satellite region. If many of these microsatellites are compromised, then the analysis loses a lot of statistical power.

Instead, he and other ancient DNA experts working in more specialized labs prefer sequencing full genomes and comparing a collection of single nucleotide polymorphisms, or SNPs (pronounced snips), which are variations in just one base pair.

The burial environment what kind of casket Dal was buried in could have an effect, for example, or any kind of treatment his body received before burial can have a impact on the condition of DNA. Only the people on the ground during the exhumation and those who actually sequence the sample will know what state the DNA is in, noted Reena Roy, an associate professor in the forensic science program at Pennsylvania State University. Without being there or using other techniques to determine how degraded the DNA actually is, she said, one can only speculate.

Roy suspects Dals DNA could be in decent shape its only 30 years old, she said. Shed still use STR analysis first, but if that didnt seem to work, shed consider using miniSTR testing, which uses the same principles but focuses on smaller DNA segments.

Bottom line: Though the circumstances around the particular paternity case may be a bit surreal, the techniques themselves are not; STR analysis is usually done in paternity cases, Roy said.

This is so routine these days.

Kate Sheridan can be reached at kate.sheridan@statnews.com Follow Kate on Twitter @sheridan_kate

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Dal's being dug up for a paternity test. But is his DNA intact? - STAT