Children with Miller-Dieker syndrome are missing part of a chromosome that aids in brain formation. The outer part of their brain (their cerebral cortex) is smooth instead of grooved. This smooth brain (lissencephaly) affects physical and mental development. They’ll also experience seizures, developmental delays and breathing issues. Unfortunately, the condition is fatal.
Miller-Dieker syndrome is a rare genetic disorder that causes the outer part of your child’s brain (the cerebral cortex) to be smooth. Their brain doesn’t have the usual complex folds, wrinkles and grooves.
A child with Miller-Dieker syndrome can have physical symptoms at birth. Or severe developmental and neurological problems may become evident by 6 months of age. A random chromosomal change often causes the syndrome. Sometimes, a child inherits a gene mutation that causes the condition. Unfortunately, there isn’t a cure. The condition is fatal, with most children passing away by age 2.
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The name “Miller-Dieker syndrome” comes from physicians James Q. Miller and H. Dieker, who first described the condition in the 1960s.
Your healthcare provider may use the medical term lissencephaly to refer to Miller-Dieker syndrome. Lissencephaly means “smooth brain.” You may also hear these terms:
Miller-Dieker syndrome is rare. It affects approximately 1 in 100,000 babies.
Children with Miller-Dieker syndrome are missing part of chromosome 17. This loss of one or more genes happens randomly for no known reason. The gene deletion may occur in the sperm, an egg or after conception as your baby develops in the womb.
Most families who have a child with Miller-Dieker syndrome have no family history of the disease. But for about 1 in 10 families, the genetic makeup of one parent’s chromosome 17 is in the wrong order. Healthcare providers call this a balanced translocation. Because the chromosome is intact, the parent doesn’t have Miller-Dieker syndrome. But the translocation can lead to a loss of genetic material for future children.
This gene deletion affects how your child’s brain forms in utero. Their brain’s outer surface (cerebral cortex) typically has layers of grooves and folds. When your child has Miller-Dieker syndrome, those grooves and folds don’t develop. Their cerebral cortex is smooth.
Miller-Dieker syndrome affects your child’s physical and mental development. The smoother their brain, the more severe the symptoms.
Your child may have:
Children with Miller-Dieker syndrome often have heads that are smaller than usual (microcephaly). They also have distinct features, such as:
Some children also have birth defects like:
A prenatal ultrasound may detect abnormal brain development or other signs of Miller-Dieker syndrome during pregnancy. Your healthcare provider may perform a genetic amniocentesis to test amniotic fluid for genetic changes that may indicate Miller-Dieker syndrome. Or you may have chorionic villus sampling (CVS) to test cells from your placenta.
After childbirth, you or your healthcare provider may notice some of the distinct facial features. Or your child may start having seizures. Most infants don’t progress past the three- or five-month child development milestones like sitting up and rolling over.
There isn’t a cure for Miller-Dieker syndrome. The condition is fatal. Treatments focus on alleviating symptoms like seizures to keep your child comfortable. Because feeding and swallowing can be difficult, your child may need tube feeding (enteral nutrition).
Loving and raising a child with a life-limiting condition is extremely challenging. You may become anxious or depressed. It’s important to take care of your physical and mental health needs while caring for your child.
You may benefit from:
There isn’t a way to prevent spontaneous cases of Miller-Dieker syndrome. If you have a child with Miller-Dieker syndrome, a genetic test can determine if you or your partner have a balanced translocation on chromosome 17. A parent who has this rearranged chromosome has a 1 in 3 chance of having another child with the condition. You and your partner should meet with a genetic counselor to discuss this risk and your options.
Unfortunately, children with Miller-Dieker syndrome have a short life expectancy. Many children experience life-threatening seizures or aspiration pneumonia. This type of pneumonia occurs when weakened throat muscles allow food and drink to enter your child’s lungs instead of their stomach.
Most children pass away by the age of 2, while some live to age 10. It’s rare for a child to survive into their teen years.
Call your child’s healthcare provider if your child has:
You may want to ask your healthcare provider:
A note from Cleveland Clinic
When your child has a life-limiting illness, it’s important to seek help from experts familiar with the disease. Your child’s healthcare provider can help you manage symptoms to keep your child comfortable. They can also connect you with resources that can support your family through this difficult time. As much as possible, try to enjoy the time your family has together and make memories that you’ll cherish.
Last reviewed by a Cleveland Clinic medical professional on 04/11/2022.
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