Dna Estudio Forense

Male-specific DNA test yields clues in criminal cases
Original Article
By PEGGY O'HARE
Copyright 2010 Houston Chronicle
Jan. 4, 2010, 11:42PM
LOOKING FOR THE Y CHROMOSOME IN DNA
Among the 20local sexual assaults solved by the Harris County Medical Examiner's Office thanks to male-specific DNA tests since June:
• 65 percent: Involved victims under 18 years old
• 38 percent: Involvedchildren under 10 years old
• 60 percent: Involved DNA originating from oral contact or dry skin cells
• 65 percent of the cases relied on testing vaginal swab samples
• 20 percent of the cases reliedon testing swabs taken from other parts of the victim's body
• 15 percent of the cases relied on testing of clothing items
Source: Harris County Medical Examiner's Office
A progressive type oftesting that separates male DNA profiles from those of females is helping the Harris County Medical Examiner's Office start solving sexual assaults and other crimes that previously yielded inconclusiveresults.
The new male-specific DNA test zeroes in on minute amounts of biological evidence, such as saliva, skin cells or a trace of semen.
The technology, which the office began using in June, hasalready yielded positive results in 20 sexual assault cases reviewed by the institution's forensic biology laboratory. Harris County Chief Medical Examiner Luis Sanchez calls the new test a “byproductof cutting-edge science.”
Known as Y-chromosome detection analysis, the test has other benefits as well. It extends the time that evidence may be collected after a sexual assault from the typical 48hours all the way up to 96 hours — or some experts say, a maximum of 120 hours.
In a rape case with multiple perpetrators, the male-specific test also will determine the number of men whoparticipated in the attack.
There are some limitations, though. The technique is not useful in assaults involving people of the same gender. It also cannot discriminate between male siblings.
“Everyone...