This page describes some of the most common health problems that have been reported in people with 18p-. It is important to remember that these concerns do not occur in everyone with 18p-. Also, we do not discuss treatment options or recommendations on this page. It is important that you speak with your team of healthcare providers to make a plan to check for and manage health concerns. In addition, the Chromosome 18 Clinical Research Center has developed Management Guidelines. These documents have more detailed information about the health problems seen in people with 18p-, including how frequently they occur. They also include specific recommendations about checking for health issues.

Lastly, it is important to understand that people with 18p- may develop health problems that are not listed on this page. As research on the chromosome 18 conditions continues, we will learn more about what to expect for people with 18p- and how to help them stay healthy and live productive, fulfilling lives.

Babies with 18p- may develop differently in the womb, leading to birth defects. These birth defects may vary from mild to severe.

Heart defects are frequently diagnosed in infants with 18p-. Several different types of heart defects have been reported in infants with 18p-.

Holoprosencephaly is another type of birth defect. In people with holoprosencephaly, the brain does not divide into two separate halves during early fetal development. There is a wide range of severity of holoprosencephaly. In some cases, this condition is severe, and the pregnancy does not survive to delivery, or the baby dies shortly after birth. Other people with holoprosencephaly may have milder forms. For example, an MRI may show that their brain has minor changes, such as a missing corpus callosum (the connection between the two halves of the brain). There may be changes in the facial features as well, such as a cleft lip and or a single incisor (front tooth) located at the midline of the mouth.

Some infants with 18p- have skeletal changes that are apparent at birth. For example, the tailbone of the spine may not develop or develop incorrectly (sacral agenesis or sacral dysgenesis). Some babies have hip dysplasia, which occurs when the thigh bone does not fit properly into the hip socket.

Lastly, hernias have been reported in some newborns with 18p-. A hernia occurs when some organs, often the intestines, push outside of the abdomen into another part of the body. Both inguinal (involving the groin region) and umbilical hernias (involving the umbilical opening) have been seen in babies with 18p-.

Newborns with 18p- often have problems at or shortly after birth. They may have feeding difficulties. For example, they may have problems latching onto the breast or bottle. They may also have problems coordinating the suck-swallow motion that is required to nurse. Some infants may frequently vomit after eating.

Infants with 18p- may also have jaundice. Jaundice is a build-up of bilirubin in the baby’s blood, leading to a yellowish color of the skin and eyes.

Some infants with 18p- have breathing problems shortly after birth.

People with 18p- have a higher chance of having changes in their nervous and muscular systems. For example, they may have changes in their muscle tone. Many have low muscle tone (hypotonia), though high muscle tone has also been seen. They may have seizures.

Dystonia is another feature of 18p-. The term “dystonia” describes an involuntary contraction of muscles. Because the muscles cannot easily relax, people with dystonia may have twisting, repetitive movements, or changes in their posture. Again, it is important to remember that not everyone with 18p- will develop dystonia.

A minority of people with 18p- are born with cataracts, or a “clouding” of the lens of the eye. As infants with 18p- get older, other vision concerns may become apparent. In particular, strabismus and ptosis are well-known features of 18p-. Strabismus occurs when the movements of the eyes are not coordinated with each other. This is frequently referred to as being “cross-eyed”. Ptosis is the medical term for “drooping eyelids”. In addition, near-sightedness and far-sightedness are fairly common.

Children with 18p- have a higher likelihood of having hearing loss. There are two types of hearing loss. Conductive hearing loss describes hearing loss that is caused when there is an obstruction to the transmission of sound from the outer ear to the inner ear. Recurring ear infections are a common cause of conductive hearing loss in people with 18p-.

The second type of hearing loss is called sensorineural hearing loss. This refers to a hearing loss that is caused by a change in the nerves that transmit signals from the ear to the brain.

People with 18p- may have conductive hearing loss, sensorineural hearing loss, or a combination of the two.

Babies and children with 18p- may have some problems with digestion. The most common digestive problem is chronic constipation.

Males with 18p- have a higher likelihood of having cryptorchidism (undescended testicles). Hypospadias has also been reported in males with 18p-. This occurs when the opening of the urethra is not at the end of the penis.

A minority of people, both male or female, may have kidney abnormalities.

Foot abnormalities are fairly common in people with 18p-. Their feet may be rotated inward or outward. They may also have flat feet.

Other bones in the body may also be affected. People with 18p- may have “bow-leggedness” (genu varum). They may develop scoliosis (an abnormal curvature of the spine) or pectus excavatum (a sunken breastbone).

Children and adults with 18p- may have changes in their growth patterns. They are often small for their age. In some cases, this is due to growth hormone deficiency. Growth hormone deficiency has been reported frequently within the literature as well as by research participants at the Chromosome 18 Clinical Research Center.

In addition to short stature, many people with 18p- have microcephaly, or a head size that falls below the 3rd percentile.

Some people with 18p- have changes in their hormone levels. These include growth hormone deficiency (discussed above), thyroid problems, diabetes, and others. Individuals with some form of holoprosencephaly, in particular, are at a significant risk for endocrine abnormalities. However, even individuals without holoprosencephaly can develop hormone problems. In some cases, a person with 18p- may have multiple hormone deficiencies. This is called hypopituitarism or panhypopituitarism. These can be very serious conditions that require treatment.

Some people with 18p- have unique skin differences. Ulerythema ophryogenes describes a rash of small reddish bumps on the faces, particularly in the eyebrow. There is also a high incidence of keratosis pilaris. This term describes small, typically white but sometimes red bumps on the arms, thighs, buttocks, or cheeks. These conditions are mostly a cosmetic concern and don’t cause pain or itching.

Low levels of IgA are found in some people with 18p-. IgA is a protein that helps fight off infections. People who have a low level of IgA are more likely to get infections and colds than those with normal levels of IgA.

Recently, we have also learned that people with 18p- seem to have a higher incidence of autoimmune conditions. Autoimmune conditions are a group of disorders that are caused when the immune system mistakenly attacks the body. Lupus, diabetes, and arthritis have all been reported in people with 18p-.

People with 18p- may have facial features that are slightly different from other family members. These changes do not affect a child’s health or development. They are simply small differences that might be noted by a doctor.

For example, people with 18p- may have ears that are lower-set and look slightly different from a “typical” ear. They may have an extra fold of skin covering the corner of the eye. The lower jaw may be slightly smaller than that of which is normally seen in people without 18p-.

Although people with 18p- may have facial features in common with one another, it is important to remember that they also have features in common with their family members.