What is miller-dieker syndrome?

Miller-Dieker syndrome (MDS) is a hereditary disorder affecting newborns and infants, caused by the deletion of a part of chromosome 17p13.3 in the DNA. MDS can often result in abnormal brain structures and changes in facial features. Due to the low life expectancy rate, it is important to understand the different diagnostic and treatment options that are available for young children with MDS.^1,4

Diagnosis of miller-dieker syndrome

Genetic testing

Chromosomes are like books which store information about how a human being functions, and contain DNA, the genetic information which builds and runs the human body. Mutations in DNA in chromosomes can lead to disease by altering how the human body functions.

Types of mutations of DNA sequences include; 

• Deletions
• Insertions
• Point mutations (change of single letters which make up the DNA sequence)

Genetic testing is a method used to look for any gene mutations in the DNA taking place, leading to a disease. There are various uses for genetic testing, including diagnosing a genetic condition, knowing if you’re a carrier and assessing the risks of developing the condition. The common techniques used for MDS are fluorescence in situ hybridisation (FISH), comparative genomic hybridisation (CGH) and karyotyping.²

Fluorescence in situ hybridisation (FISH)

This is a cytogenetic technique used to identify chromosomal variants using fluorescent probes and a microscope. This implies that details on chromosomal duplications or deletions, and any structural rearrangements will be known.⁵ 

Comparative genomic hybridisation (CGH)

A method used to find chromosomal copy variations without using cell culturing. In the context of Miller-Dieker syndrome, this technique can help determine how extensive the deletions are, it may vary in size or showcase severe symptoms and can detect any atypical deletions that FISH could miss.⁶ 

Karyotyping 

A karyotype is a photomicrograph of the chromosomes of a dividing cell. Karyotyping is a technique used to identify chromosomal abnormalities. Karyotype tests are usually done by taking samples of blood, bone marrow, amniotic fluid and CVS. These samples are then cell-cultured allowing them to grow and divide before they are analysed.^7,8  

Prenatal diagnosis

A prenatal diagnosis is when the fetus is tested for any specific genetic disorders that may have been inherited or to identify any abnormalities that may be present before birth. Different prenatal diagnosis methods, such as chorionic villus sampling (CVS) and amniocentesis are available.³ 

Chorionic villus sampling (CVS)

CVS is a test used to check if the baby has a genetic or chromosomal condition. This is done by taking a sample of cells from the placenta through the use of transcervical (inserting a catheter through the abdominal and uterine walls to collect chorionic tissue) or transabdominal sampling (insertion of a needle). The procedure is usually performed between 10-13 weeks of gestation to diagnose fetal chromosomal, metabolic or DNA abnormalities.⁹  

Amniocentesis 

Amniocentesis is the removal of an amnionic fluid sample from the uterus to determine the changes in the fetus developing a certain condition. This procedure is usually performed after 15 weeks by placing a needle through the patient’s abdominal and uterine walls into the amniotic cavity to withdraw fluid for analysis. However, there are a few risks associated with this test, such as; ¹⁰

• Miscarriage
• Amniotic fluid leakage
• Fetal damage by the needle
• Contamination of the sample
• Infection 

Fetal MRI (magnetic resonance imaging)

A prenatal MRI on the fetus is a useful way to detect Miller-Dieker syndrome, as it is a rare condition interfering with brain development. A common characteristic found on the MRI is lissencephaly, a smooth brain surface with a lack of normal folding in the brain.^{11,12, 13} 

Treatments for miller-dieker syndrome

There is no effective cure available for newborns or infants with Miller-Dieker syndrome. However, there are treatments available to help with managing symptoms. These can include seizure control (prescribing medications), a feeding tube (difficulty swallowing or chewing foods) and therapy (physical, occupational and speech therapy).¹ 

FAQs

How do you diagnose miller-dieker syndrome?

An ultrasound scan before a baby is born will show signs of differences in brain development, such as lissencephaly, whereby the brain appears smooth and without grooves, opposite to what is seen in healthy brain development. Amniotic fluid from the baby’s mother can be tested for genetic mutations indicating Miller-Dieker syndrome. After childbirth, diagnosis involves noting distinct facial features, seizure occurrence and slowed development in childhood.

How do you treat miller-dieker syndrome?

Although Miller-Dieker syndrome has no cure, it can be managed with supportive care and therapies to allow patients to live a healthy life. Treatment includes;

• Prescribing antiepileptic seizure medication
• Speech and occupational therapy for speaking, motor skills such as movement, and stiffness of muscles
• Provision of a feeding tube to aid a child’s eating and swallowing

A doctor should always be consulted on treatment options tailored to the patient's needs.

Summary 

In summary, there are different methods used to help with the diagnosis and treatment of Miller-Dieker syndrome (MDS), such as genetic testing and prenatal diagnostic methods. Enhanced treatment and outcomes are possible when patients understand the different diagnostic and treatment options. There is continuous research happening to help patients with miller-dieker syndrome.