Cyclopia is a rare condition that causes a child to be born with one eye, no nose, and a proboscis (a nose-like growth) above the eye. It's caused by a severe malformation of the baby’s brain early in the pregnancy.
Cyclopia often results in a miscarriage or stillbirth. Survival after birth is mostly a matter of a few hours. It occurs in about 1 in 100,000 newborns. There’s no way to prevent cyclopia and there’s no cure.
Most cases of cyclopia are usually detected early if you receive proper prenatal care. The World Health Organization (WHO) says that the first prenatal visit should be as early as possible in pregnancy, preferably in the first trimester.
What Are the Causes of Cyclopia?
Cyclopia is a symptom of a brain condition called alobar holoprosencephaly. It develops during the earliest parts of pregnancy, usually in the first month. In a typical embryo, that’s the time when the brain would split into two hemispheres. In the case of cyclopia, the brain does not divide the way it should. Also, the rest of the head and face don’t develop typically.
The most notable effect of the condition is the atypical development of the eyes. Instead of two eyes placed on opposite sides of the midline of the face, embryos with cyclopia may only develop a single eye in the middle of the face. Alternatively, there may be two eyeballs in a single socket.
Other facial differences due to cyclopia include:
- No nose
- A tubular proboscis instead of a nose
- Misplacement of nose or proboscis, either above the eye socket or in the back of the skull
- Cleft palate
- Cleft lip
- Small skull
Risk Factors
Risk factors associated with cyclopia include:
Fetal factors such as:
- Female sex
- Chromosomal abnormalities
- Multiple pregnancies, especially twinning
Maternal factors including:
- Previous miscarriages
- Drugs during pregnancy (e.g. alcohol, aspirin, lithium, anticonvulsants, hormones, retinoic acid, anticancer agents, and fertility drugs)
- Ultraviolet light
- Consanguineous marriages (marrying from the same ancestry)
- Exposure to insulin during pregnancy
- Gestational diabetes
- Exposure to an alkaloid poison called cyclopamine
How Is Cyclopia Diagnosed?
Cyclopia diagnosis may be done through an ultrasound. This test takes place when your baby is in the womb. The ultrasound can also determine signs of abnormalities in the internal organs and the brain.
Unclear images may cause your doctor to ask for more tests. A fetal MRI will create images of the fetus and other internal organs using radio waves and magnetic fields. These may help to confirm the diagnosis. MRIs and ultrasound have no risks to you and your baby.
Outcomes of Cyclopia
In some cases, cyclopia and holoprosencephaly are present along with other genetic syndromes that cause additional issues as the embryo develops. Unfortunately, cyclopia results in such severe physical problems that it is incompatible with life. Most babies with the condition are stillborn or pass away shortly after birth. There are no cases of babies with cyclopia living more than 6 months after birth.
A significant number of babies born with cyclopia may also have malformations of their chromosomes.
Cyclopia can be inherited. If your baby has cyclopia, inform your immediate family members who may also be starting their families. It is essential to tell them of any other minor forms of holoprosencephaly. Genetic testing is very helpful in determining the risks of children being born with inherited diseases.
Other Forms of Holoprosencephaly
Alobar holoprosencephaly is the most severe form of the condition, but it isn’t the only type. Other variations include:
Semi-lobar holoprosencephaly. In this condition, the left and right sides of the brain are fused along the frontal and parietal lobes. The condition results in facial features such as a flattened nose, one nostril, a median or bilateral cleft lip, or a cleft palate.
Lobar holoprosencephaly. There is more division of the brain, but the cerebral hemispheres are fused in the frontal cortex. This can cause a bilateral cleft lip, closely spaced eyes, or a depressed nose. The features might be unaffected.
Middle interhemispheric variant. A middle section of the brain is fused. This could result in closely spaced eyes and a depressed and narrow nose. There also may be no facial differences at all.
There are health conditions that can accompany holoprosencephaly, though not all children will have the same set of issues. Some of the problems that might occur include:
- Seizures
- Hydrocephalus (fluid on the brain)
- Neural tube defects
- Pituitary dysfunction
- Short stature
- Feeding difficulties
- Heart and lung problems
- Developmental delay and intellectual disability
Life expectancy for children with holoprosencephaly depends on the severity of the condition. In some cases, children have other health problems that cause significant concerns. In other cases, children may only have mild disabilities and no physical limitations.
