Donnai-Barrow Syndrome
Patient Information
Characteristics
Background and History
This is a rare genetic syndrome involving multiple systems including the eye, kidneys, skeleton, and facial features. It was first reported by two physicians in 1993 and less than 50 patients have been reported since.
Clinical Correlations
The facial appearance is characteristic with a prominent forehead, wide-set and prominent eyes, posteriorly rotated ears, and a short nose with a flattened bridge. Many have developmental delays and a few cases have had seizures. Some brain structures such as the corpus callosum (which connects the two halves of the brain) may be missing. There are often hernias of the diaphragm and the umbilicus. There is often an increase of protein in the urine.
The eyes are large which leads to a high degree of near-sightedness. This increases the risk of developing retinal detachments and the result is blindness in some individuals. Cataracts and maldevelopment of the retina (macula) may be present. The iris may resemble a keyhole (coloboma) and often has a decreased amount of pigment.
Genetics
Inheritance
This is an autosomal recessive disorder requiring the presence of two mutations. The normal parents must each carry a single copy of the mutation and thus each of their offspring has a 25% risk of inheriting both mutations and having Donnai-Barrow syndrome.
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
Diagnosis and Prognosis
The diagnosis is often made by a pediatrician or medical geneticist and may be confirmed by an ophthalmologist. There is no treatment for the syndrome itself, but surgery for the hernias, cataracts, and retinal detachments may need to be done. Hearing aids can be helpful and seizure medicines may be required. Full eye examinations throughout life are necessary to detect and treat retinal disease to reduce the risk of blindness.
Web Resources
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