Tetrasomy 18p: Health Concerns
This page describes some of the most common health problems that have been reported in people with Tetrasomy 18p. It is important to remember that these concerns do not occur in everyone with Tetrasomy 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 Tetrasomy 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 Tetrasomy 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 Tetrasomy 18p and how to help them stay healthy and live productive, fulfilling lives.
Problems in the Newborn Period
Newborns with Tetrasomy 18p often have problems at birth or shortly thereafter. The most common problem is nursing/feeding difficulties. Infants 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 vomit frequently after eating. In some cases, a referral to a speech language pathologist may be recommended. In more serious cases, a feeding tube may be required. Supplementing their diet with a high-calorie formula may also be recommended to help the infant gain weight.
Infants with Tetrasomy 18p may have other problems. Jaundice is a build-up of bilirubin in the baby’s blood, leading to a yellowish color of the skin and eyes. Occasionally, this resolves on its own. However, many infants with Tetrasomy 18p require treatment for jaundice. Treatment is usually very easy. Typically, the baby is simply placed under a light. This helps break down the extra bilirubin in the baby’s blood.
Some infants with Tetrasomy 18p have breathing problems shortly after birth. To assist with the baby’s breathing, doctors may have to provide extra oxygen. This may be done by putting a tube into the baby’s nose.
Neurological Changes
People with Tetrasomy 18p usually have some changes in their muscle tone. They may have increased or decreased muscle tone. This is called hypertonia and hypotonia, respectively. Changes in muscle tone can lead to other difficulties. For example, infants with low muscle tone may have difficulty eating because the muscles surrounding the mouth are weak. Children with high muscle tone may also have spasticity. This means that there are uncontrolled muscle spasms when the muscle is stretched by someone else. Changes in muscle tone and spasticity may also lead to delays in meeting developmental milestones, such as sitting without support and walking. Physical, occupational, and speech therapy may improve some of these problems.
Seizures also happen more often in people with Tetrasomy 18p than in people without Tetrasomy 18p. If seizures are suspected, a doctor may request an electroencephalogram (EEG). They may also refer the patient to a neurologist to help manage the seizures.
Spina bifida has been reported in a small number of people with Tetrasomy 18p. Spina bifida, also known as myelomeningocele, is a type of birth defect. It is an opening in the spinal cord that occurs early in the first trimester of pregnancy. This can lead to paralysis of the legs, problems with the kidneys and urinary system, and hydrocephalus (extra fluid in the brain). Spina bifida is usually treated by a team of specialists, including neurosurgeons, therapists, and urologists. To find a spina bifida clinic in your area, visit the Spina Bifida Association website.
MRI Changes
Some people with Tetrasomy 18p have changes in the structure of their brain that can only be detected with an MRI. For example, several people have been identified with a thin corpus callosum. The corpus callosum is the bundle of nerves that connect the right and the left sides of the brain. Other people have been diagnosed with “enlarged lateral ventricles”. This simply means that the spaces that contain the cerebrospinal fluid in the brain are larger than expected.
Eyes and Vision
Eye problems are common in people with Tetrasomy 18p. The eyes may be misaligned (strabismus). People with Tetrasomy 18p may also have problems with their vision. They may be near-sighted, far-sighted, or have astigmatism.
Because vision problems are possible, people with Tetrasomy 18p should have regular eye exams.
Ear Infections
Recurrent ear infections are common in babies and toddlers with Tetrasomy 18p. They occur in approximately 50% of individuals. Untreated ear infections may lead to hearing problems. Therefore, it is important to identify and treat ear infections. Most of the time, medicine is prescribed to treat the ear infection. Some children may require surgery to insert tubes in the ears to reduce the number of ear infections.
Hearing
Although hearing loss does occur in some people with Tetrasomy 18p, the majority do not have any hearing problems. It appears that those that do have hearing loss typically have a mild to moderate hearing loss.
Although hearing loss is not very common in people with Tetrasomy 18p, it is still important to screen them for any potential hearing problems. This will help find and treat hearing loss early.
Palatal Abnormalities
The palate is the roof of the mouth. Many people with Tetrasomy 18p have changes in the shape of their palate. For example, the palate may be highly arched and/or narrow. In some cases, these changes may lead to some difficulties with speech. It is important to understand that this is not the same thing as a cleft palate, in which the palate does not completely close.
If a physician feels that a change in the palate may lead to speech problems, he or she may refer a patient to an ENT (a doctor who specializes in problems of the ears, nose, and throat).
Heart
Approximately 30% of people with Tetrasomy 18p have some type of heart defect. Many of the heart defects are “septal defects”, meaning that there is a hole in between the two sides of the heart. In some cases, these defects close without any intervention. However, in some cases, surgery is necessary.
Because heart defects are more common in babies with Tetrasomy 18p, they may have an ultrasound of the heart (echocardiogram) to rule out such defects.
Gastrointestinal Changes
Gastrointestinal problems are fairly common in people with Tetrasomy 18p. The most common concern is constipation. Reflux also occurs somewhat frequently. Structural malformations of the gastrointestinal system are not very common. However, pyloric stenosis and hernias have been reported. Pyloric stenosis is a closure or narrowing of the place where the stomach contents enter the intestines. A hernia occurs when some organs, often the intestines, push outside of the abdomen.
If there is a concern for gastrointestinal problems, a referral to a gastroenterologist is appropriate.
Genitourinary Changes
Males with Tetrasomy 18p may have some changes in the genital region. The testicles may not be fully descended (cryptorchidism). The opening of the urethra may not be at the end of the penis (hypospadias). In some cases, surgery may be required to correct these concerns.
Some people have vesicoureteral reflux. This occurs when urine flows from the bladder up towards the kidneys. This can lead to recurrent urinary tract infections. However, structural changes in the kidneys occur in a small number of males and females with Tetrasomy 18p. A doctor may order an abdominal ultrasound to rule out structural changes in the kidney.
Orthopedic Changes
Some people with Tetrasomy 18p may have minor changes in their hands and feet. For example, they may have narrow feet, or they may have fingers and toes that are partially fused. They may have camptodactyly. Camptodactyly occurs when fingers are in a permanently “flexed” position. However, these issues seldom require medical intervention.
People with Tetrasomy 18p may have scoliosis or kyphosis. This simply means that they have an abnormal curvature of the spine. Flat feet are another common orthopedic concern.
People with foot or spinal changes may see an orthopedic specialist. Braces and inserts, surgery, and therapy may help in addressing orthopedic concerns.
There has been some evidence suggesting that people (including children) with Tetrasomy 18p have decreased bone mineral density, meaning that they may be more susceptible to bone fractures. A DEXA scan (bone scan that determines bone mineral density) may be considered to establish a baseline. Families may also wish to speak with their physician about calcium and vitamin D supplementation. Much research remains to be done to understand whether and how bones are affected in individuals with Tetrasomy 18p.
Allergy and Immunology
In recent years, several individuals have been diagnosed with eosinophilic esophagitis (EoE). EoE is an inflammatory disease that affects the tube that connects the mouth to the stomach (the esophagus). Some symptoms include feeding difficulties and failure to thrive, reflux that doesn’t respond to therapy, difficulty swallowing, nausea, and vomiting. For more information about EoE, visit the American Partnership for Eosinophilic Disorders.
If there is a concern for EoE, a gastroenterologist can help make a diagnosis and discuss treatment and management options.
Growth
Children and adults may have changes in their growth patterns. Children with Tetrasomy 18p may be small for their age. In a minority of cases, this is due to growth hormone deficiency. Treatment with growth hormone helps normalize growth and may improve a child’s development.
If there is a concern regarding growth, a person can see a pediatric endocrinologist to rule out growth hormone deficiency. Drs. Jannine Cody and Daniel Hale have written an article for the Chromosome 18 Registry & Research Society about growth hormone deficiency in children with chromosome 18 abnormalities.
- • Growth Hormone Deficiency and Chromosome 18 Abnormalities, Chromosome 18 Communique, Spring 1999.
In addition to short stature, many people with Tetrasomy 18p have microcephaly, or a head size that falls below the 3rd percentile.
Bone Issues
There has been some evidence suggesting that people with Tetrasomy 18p have decreased bone mineral density, meaning that they may be more susceptible to bone fractures. A DEXA scan (bone scan that determines bone mineral density) may be considered to establish a baseline. Families may also wish to speak with their physician about calcium and vitamin D supplementation. Much research remains to be done to understand whether and how bones are affected in individuals with Tetrasomy 18p.
Facial Features
People with Tetrasomy 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.
They may have changes in the structure or the placement of the ears. They may have a small mouth, and the area above the upper lip may be smooth. The upper lip may be thin. Their chin may be either larger or smaller than other children’s chins.
Although people with Tetrasomy 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.
Lifespan
When a child is diagnosed with Tetrasomy 18p, one of the family’s first questions is often, “What does this mean for my child’s lifespan?” The Chromosome 18 Clinical Research Center has published data regarding life expectancy in people with Tetrasomy 18p. There are 56 individuals with Tetrasomy 18p in the study. In this group, there has been at least one instance of premature death in a person with Tetrasomy 18p. A thirteen year old girl passed away unexpectedly due to sudden heart arrest following a day-long history of nausea, vomiting and lethargy. The direct cause of her sudden deterioration is unknown. She had a history of severe and untreated constipation as well as possible seizures which may have contributed to her