There’s a new disorder among children called the Loeys-Dietz syndrome. Physicians and geneticists from The Johns Hopkins University write about it in this article. They studied 65 children who had a diagnosis of Loeys-Dietz confirmed with genetic testing.
What is Loeys-Dietz syndrome? It’s a disorder that affects multiple body systems including the skeletal system, the heart (cardiac) and blood vessels (circulatory system), and the skin. This problem is caused by a genetic mutation. They’ve even found the gene that has gone bad: TGF-ßR1 or TGF-ßR2. This particular gene is responsible for coding the growth factor-beta receptor.
That probably doesn’t mean much to the average reader. But for the affected child it can mean the formation of aneurysms (weak blood vessel walls that can burst and bleed), scoliosis (spinal curvature), very thin skin, chest deformities, and severe foot deformities (clubfoot). Other problems observed in children with Loeys-Dietz include an unstable cervical spine (neck), small jaw, cleft palate, hip dysplasia, and many other skeletal deformities.
Some features of this disorder are very distinctive (e.g., cleft palate, clubfoot). There may be a condition called hypertelorism, which is an abnormal distance between the eyes. Craniosynostosis is another telltale skeletal feature. This refers to the premature fusion of the cranial (skull) bones. Early fusion of this type prevents the brain from growing normally. The child ends up with an abnormally shaped head and face. Delays in development (especially motor skills) are also common when brain growth is restricted.
There are several other conditions that have similar effects (e.g., Ehlers-Danlos syndrome, Marfan syndrome, Shprintzen-Goldberg syndrome) so the diagnosis isn’t always straight forward. That’s why the authors put this information together. By studying 65 children with Loeys-Dietz syndrome and comparing them to these other connective tissue disorders, they were able to better define this newly recognized syndrome.
For example, two distinctive signs of Marfan syndrome are also present in up to one-fourth of all children with Loeys-Dietz syndrome. One is the positive thumb or Steinberg sign. The other is the positive wrist or Walker-Murdoch sign. If the patient puts the thumb across the palm and closes the fingers and the thumb pokes out the other (little finger) side, there’s a positive thumb sign. If the patient can circle the forearm with the thumb and little finger of the other hand and cover the entire nail of the little finger with the thumb, there is a positive wrist sign.
Of course, the condition can be confirmed with genetic testing and that may be important given the seriousness of the aneurysms (they can be life-threatening). Early treatment to control the amount of blood pressure against the thin-walled vessels can help prevent rupture and hemorrhage. Malformations of the upper cervical spine may require fusion surgery to stabilize the head and neck and keep pressure off the spinal cord. Scoliosis may be treated with spinal bracing and/or fusion surgery when the curvature is large enough to compromise lung function (breathing) or digestion.
The authors conclude that the risks of untreated problems in Loeys-Dietz such as aneurysms and neck instability make it imperative that this problem is diagnosed early. In the past, children with the clinical features of Loeys-Dietz as described here would have been considered a subgroup of the Marfan syndrome. The discovery that there are mutations in a specific gene (TGF-ßR1 or TGF-ßR2) puts this syndrome in a category by itself. Pediatricians and primary care physicians who see children with combinations of any of the features mentioned should refer the patient to a genetic specialist as soon as possible.