Research in South America on a rare ear defect could help pinpoint risk factors for some of the most common birth defects in the United States.

Some 120,000 babies in the United States are born each year with birth defects, according to the March of Dimes. The most common birth defects are heart defects, cleft lip and cleft palate, Down syndrome and spina bifida.

Microtia, an ear abnormality

Researchers don’t know what causes many birth defects, but Daniela Luquetti, MD, PhD, of Seattle Children’s Research Institute, hopes to change that. She studies microtia, an abnormality of the external ear often accompanied by hearing loss, in South America. Patients with microtia have a small, abnormally shaped or missing ear and usually need surgery or an ear implant to treat the condition.

Looking for clues to birth defects in South America

In the United States, microtia occurs in one or two children per 10,000. The prevalence of microtia is higher in Colombia and Ecuador, two of the countries in Luquetti’s research sphere.  She and experts from the Latin American Collaborative Study of Congenital Malformations are looking for genetic mutations that contribute to the condition.  They are also investigating whether environmental factors, such as dietary differences and the region’s uniquely high altitude, play a role.

“These countries have cities located as high as 16,000 feet above sea level, which is pretty high,” said Luquetti, who is also a member of Children’s Craniofacial Center. Seattle at its highest point is 521 feet above sea level; the so-called Mile-High City of Denver is 5,280 feet above sea level. “There is a hypothesis that altitude could be related to microtia,” Luquetti said. Researchers have also thought the conditions could be linked to hypoxia, a condition in which the body is deprived of oxygen, which happens at these higher altitudes.

“We are also looking at risk factors like the use of tobacco or alcohol during pregnancy—pulling from cases of children with microtia—and studying genetics, collecting demographic and family information and DNA,” said Luquetti.  “Learning more about the specific causes of this condition could potentially help in the care of children with microtia. If a child has a mild ear malformation, what is the likelihood that he or she will also have hearing loss, and which specialists need to see the child and how many exams are needed to properly characterize the condition?”

Luquetti’s research could one day help pregnant women reduce the risk of birth defects.  For instance, doctors now know that having women take a folic acid supplement can prevent major birth defects of the brain and spine, including spina bifida and anencephaly.

Joining forces to help understand, prevent birth defects

Luquetti’s work overlaps with Carrie Heike, MD, MS, also of Seattle Children’s Research Institute and Children’s Craniofacial Center.  Heike, Luquetti  and colleagues created a network known as FACIAL (Facial Asymmetry Collaborative for Interdisciplinary Assessment and Learning) with other craniofacial centers in the United States to study craniofacial microsomia, the second most common birth defect in the world. 

“Microtia is considered by some investigators to be part of the same spectrum as craniofacial microsomia,” Luquetti said. “And, as I mentioned, the one or two in 10,000 prevalence of microtia in the U.S. is not a big number.  We need more participants in our ongoing studies to have more meaningful results and the only way to do that is to work together.” 

When you combine all birth defects into one set of numbers, Luquetti said it’s the leading cause of mortality for children in the United States.  She hopes to have results to share from her research by 2016.

January is national birth defects prevention month.  The Centers for Disease Control and Prevention has detailed information on birth defects and prevention.  The CDC also has tracking information on birth defects from 15 states.

The National Birth Defects Prevention Study has surveillance and research data from Arkansas, California, Georgia, Iowa, Massachusetts, New Jersey, New York, North Carolina, Texas, and Utah.