Prenatal MRI Detects Rare Genetic Disease in Newborn

In a case believed to be a United States first, a radiology team has utilized prenatal magnetic resonance imaging (MRI) to detect an often-misdiagnosed genetic disease, congenital chloride diarrhea (CCD; also congenital chloridorrhea).

The disorder can cause severe dehydration and serious metabolic disturbances in newborns if not treated quickly. "This is a disease where early diagnosis is the key to a good outcome,” said Richard Barth, M.D., chief radiologist at the Lucile Packard Children's Hospital (Palo Alto, CA, USA), and the physician who recognized the unusual case. Congenital chloride diarrhea is so rare, with only approximately 250 total cases reported worldwide, that infants with the disease are frequently erroneously treated for other diarrhea-causing ailments. "If the patient's fortunate, you could stumble onto this diagnosis,” said Dr. Barth, a professor of pediatric radiology at the Stanford University School of Medicine (Stanford, CA, USA). The case was the first instance of CCD Dr. Barth had ever seen.

The diagnosis is one of only four known cases of CCD diagnosis ever made via prenatal MRI scanning. A scientific report on the four cases, including Dr. Barth's case and three from France, was published online December 9, 2010, in the journal Ultrasound in Obstetrics & Gynecology. The report is a collaboration between Dr. Barth and a team of French scientists in Marseilles.

Dr. Barth made his diagnosis in February 2009 when an expectant mother was referred to him for follow-up of an abnormal prenatal ultrasound. The ultrasound showed classic signs of bowel obstruction, a typical fetal problem. To get more information about the fetus, Dr. Barth ordered an MRI scan, which gave him a surprise that could not have been detected by ultrasound: Instead of showing the fetal colon filled with solid waste, as in a bowel obstruction, it was filled with fluid. This important clue, found due to the Packard team's expertise in fetal MRI, pointed Dr. Barth toward the obscure diagnosis of CCD.

When the baby was born at Packard a few weeks later, Dr. Barth collaborated with obstetrics and neonatology teams in the hospital's Johnson Center for Pregnancy and Newborn Services to ensure the infant's fluid and electrolyte levels would be monitored beginning at birth. This was needed because the gene mutation that causes CCD damages a salt-transporting protein in the intestine. The abnormality stops the body from absorbing essential electrolytes, causing patients to have large amounts of watery, high-salt diarrhea.

"These babies can go into shock and die because of the tremendous electrolyte imbalance at birth,” said Maurice Druzin, M.D., professor and service chief of obstetrics and gynecology at Packard Children's. Without the prenatal diagnosis, it could easily have taken physicians a few days to figure out what was going on, Dr. Druzin added. "The baby could have been in serious trouble by that time,” he said. Untreated patients who survive early life may suffer permanent kidney damage, feeding problems, severe malnutrition, and delays in growth and motor development.

"In this case, the neonatology team was not just monitoring the baby's electrolytes, but also taking special precautions in terms of feeding,” stated neonatologist Susan Hintz, M.D., associate professor and medical director of the Center for Comprehensive Fetal Health & Maternal and Family Care at Packard Children's. "We took these steps due to the strong possibility that this was CCD.”

For infants whose CCD is detected early, treatment is simple: intravenous fluid and salt replacement can compensate for their ongoing diarrhea. As they get older, patients may take extra liquids and salts by mouth, or they can opt for newer treatments. For instance, the little girl Dr. Barth diagnosed is now taking an oral medication that modifies her body's salt uptake and reduces diarrhea. Although these treatments do not cure the disease, prompt diagnosis and treatment allow patients to lead normal, healthy lives.

"Dr. Barth's experience with difficult cases and the depth of his familiarity with the fetal imaging scientific literature really helped our entire team provide the best possible care for this mother and baby,” Dr. Hintz said.

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