Achondroplasia – Dwarfism: Symptoms, Causes, Genetics, Diagnosis, Treatment

Medically Reviewed by Dr. K on 13 May 2022.

What Is Dwarfism?

Dwarfism is a condition in which a person is short in stature due to their genes or a medical condition. Little People of the World Organization (LPOTW) and Little People of America (LPA) describe it as an adult height of less than 4 foot 10 inches as a result of a medical or hereditary disorder. Some organisations raise the height limit for some types of dwarfism to 5 feet, but the average adult with dwarfism stands at 4 feet.

Dwarfism is divided into two types: disproportionate and proportionate dwarfism.

Disproportionate dwarfism is described by a normal-sized torso with shorter arms and legs, or a shorter trunk with longer limbs.

The body parts are in proportion but shortened in proportionate dwarfism.

Dwarfism Symptoms

Dwarfism has a variety of symptoms in addition to short stature, which varies depending on the type.

Disproportionate dwarfism symptoms

Disproportionate dwarfism usually does not interfere with intellectual development unless the child also suffers from other conditions, such as hydrocephalus (excess fluid around the brain).

The below are some of the signs and symptoms of disproportionate dwarfism:

  • Adults are generally around 4 feet tall
  • Small limbs, particularly in the upper arms and legs, and a medium-sized torso
  • Short fingers
  • Wide spaces between the middle and ring fingers
  • Reduced elbow mobility
  • Disproportionate large head
  • Prominent forehead
  • Flattened bridge of the nose
  • Bowing of legs that progressively worsens over time
  • Swaying of the back that progressively worsens over time

Spondyloepiphyseal dysplasia congenita is a rare condition that affects certain individuals with excessive dwarfism (SEDC). Adults with SEDC are 3 to 4 feet tall and may exhibit the following symptoms:

  • Very short trunk
  • Short neck, arms, and legs, with average-size hands and feet
  • Broad chest
  • Flattened cheekbones
  • Cleft palate – an opening in the roof of the mouth
  • Unstable neck bones
  • Deformed hips where the thigh bones turn inward
  • Twisted feet
  • Hunched upper back that progressively worsens
  • Swayed lower back that progressively worsens
  • Arthritis
  • Joint mobility problems
  • Impaired vision or hearing

Proportionate dwarfism symptoms

Proportionate dwarfism is affected by a medical disorder that affects growth and development and is present at birth or occurs during childhood. Low levels of growth hormone released by the pituitary gland are a common cause.

The head, arms, and legs are all smaller in proportionate dwarfism. But they’re all in proportion to one another. Organ systems could also be smaller.

The following are other symptoms of proportionate dwarfism in children:

  • Slower rate of growth than expected for their age
  • Height lower than the third percentile on standard charts for age
  • Delayed or no sexual development during the teen years


Dwarfism Causes

There are around 400 different forms of dwarfism. Metabolic and hormonal abnormalities, such as growth hormone deficiency, are among the causes of proportionate dwarfism.

Genetic dwarfism, also known as skeletal dysplasias, is the most prevalent form of dwarfism. Skeletal dysplasias are diseases that cause excessive dwarfism due to irregular bone development.

This includes:

Achondroplasia. Achondroplasia is the most prevalent cause of dwarfism, accounting for 70% of cases. It affects one out of every 26,000 to 40,000 babies and is visible at birth. Achondroplasia is characterised by a comparatively long trunk with compressed upper arms and legs. Achondroplasia also has the following characteristics:

  • Enlarged head with a prominent forehead
  • Flattened bridge of the nose
  • Protruding jaw
  • Crowded and misaligned teeth
  • Forward curvature of the lower spine
  • Bowed legs
  • Flat, short, broad feet
  • “Double-jointedness"

Spondyloepiphyseal dysplasias (SED). SED is a less prevalent type of dwarfism that affects around one in every 95,000 babies. Spondyloepiphyseal dysplasia is a category of disorders marked by a compressed trunk that may not be noticeable until an infant is between the ages of 5 and 10. Other features to consider are:

  • Clubfeet
  • Cleft palate
  • Severe osteoarthritis in the hips
  • Weak hands and feet
  • Barrel-chested appearance

MIT department of biology

Diastrophic dysplasia. Diastrophic dysplasia is an unusual type of dwarfism that affects around one in every 100,000 babies. It causes people to have shorter forearms and calves (this is known as mesomelic shortening).

Other indicators can include:

  • Deformed hands and feet
  • Limited range of motion
  • Cleft palate
  • Ears with a cauliflower appearance

Turner syndrome. Only females are affected by this genetic disease. A incomplete or partially missing X chromosome is the cause. Turner syndrome affects girls who only have one completely functional X chromosome from each parent, rather than two.

Dwarfism Genetics

A genetic defect causes skeletal dysplasia. The gene mutation will happen spontaneously or be passed down over the generations.

Diastrophic dysplasia and, in most cases, spondyloepiphyseal dysplasias are recessive disorders. To be infected, an infant must inherit two copies of the mutant gene, one from the mother and the other from the father.

Achondroplasia, on the other hand, is a dominantly inherited condition. That means a child only needs one copy of the mutated gene to develop skeletal dysplasia of that kind. A infant born to a couple of both parents having achondroplasia has a 25% risk of being of average height. However, there is a 25% risk that the infant will inherit all dwarfism genes, which is known as double-dominant dwarfism syndrome. This is a life-threatening illness that normally leads to miscarriage.

Parents with children with achondroplasia also do not have the mutant gene. Around the moment of conception, the child's mutation happens naturally.Doctors are baffled as to whether a gene mutates. It's an ostensibly spontaneous phenomenon that can occur at any time during a pregnancy. When average-sized parents have a child with dwarfism as a result of a random mutation, other offspring are unable to inherit the mutation.

Small stature can be caused by a variety of factors, including pituitary conditions that impair development and metabolism, kidney failure, and issues with the body's capacity to digest nutrients, in addition to hereditary skeletal dysplasia.

Dwarfism Diagnosis

Dwarfism can be detected in utero, at birth, or during childhood, and can be identified with X-rays and a physical examination. Genetic tests may validate a diagnosis of achondroplasia, diastrophic dysplasia, or spondyloepiphyseal dysplasia. If there is a risk about a medical disorder, prenatal tests can be performed.

Dwarfism can not become apparent until later in a child's life, where symptoms of dwarfism prompt parents to get a diagnosis. Here are some signs and symptoms to monitor for in children who may have dwarfism:

  • A larger head
  • Late development of certain motor skills, such as sitting up or walking
  • Breathing problems
  • Curvature of the spine
  • Bowed legs
  • Joint stiffness and arthritis
  • Lower back pain numbness in the legs
  • Crowding of teeth

These examinations can also be used by doctors to help detect dwarfism:

The way you look. As a child grows, the skeleton and facial structures of children with dwarfism can change.

Comparisons of charts

Your child's height, weight, and head circumference would be assessed at routine checkups and matched to percentiles for normal growth for their age. If your child displays some signs of premature development, more regular measurements might be needed.


On ultrasounds of a foetus during birth, doctors can notice symptoms of achondroplasia, such as shorter limbs, or other causes of dwarfism. X-rays of babies or children which reveal that their arms or legs are not developing normally, or that their skeleton is showing signs of dysplasia. MRI scans will reveal any anomalies affecting hormone output in the pituitary gland or hypothalamus.

Genetic testing

To scan for genetic mutations related to dwarfism, DNA testing may be performed before or after birth. DNA testing to confirm the X chromosomes of girls with alleged Turner syndrome could be needed. If parents want to have more children, DNA testing may help them prepare their family.

Family history

Pediatricians can equate the height and age of other members of the family, such as brothers, to the child with presumed dwarfism.

Hormone tests

Growth hormone levels can be checked to see if they're low.

Dwarfism Treatments

Any of the complications involved with dwarfism can be avoided or mitigated with early diagnosis and treatment. Growth hormone can be used to combat dwarfism caused by a lack of growth hormone.

People with dwarfism also experience orthopaedic or medical problems. Those can be treated in a variety of ways, including:

  • A shunt is inserted into the brain to remove extra fluid to release pain.
  • A tracheotomy – surgical procedure that improves ventilation through narrow airways.
  • Surgical procedures to correct deformities such as a cleft palate, club foot, or bent knees.
  • surgery to remove tonsils or adenoids – To boost respiratory issues caused by large tonsils, small facial muscles, and/or a small chest
  • To alleviate spinal cord compression, surgery to enlarge the spinal canal (the opening into which the spinal cord passes) is performed.
  • Extended limb lengthening is a controversial surgery that requires many operations, in part because of its complications. Only adults are subjected to this procedure.

Other treatment may include:

  • Physical therapy to strengthen muscles and increase joint range of motion
  • Back braces to improve curvature of the spine
  • Placement of drainage tubes in the middle ear to help prevent hearing loss due to repeated ear infections
  • Orthodontic treatment to relieve crowding of teeth caused by a small jaw
  • Nutritional guidance and exercise to help prevent obesity, which can aggravate skeletal problems

Dwarfism Complications

Disproportionate dwarfism causes changes to the limbs, back, and head size that could cause complications like these:

  • Arthritis
  • Back pain or breathing difficulties due to hunched or swayed back
  • Bowed legs
  • Crowded teeth
  • Delayed motor skills development
  • Frequent ear infections and possibly hearing loss
  • Hydrocephalus (fluid on the brain)
  • Pressure on the spine at the base of the skull
  • Sleep apnea
  • Spinal stenosis, a narrowing of the spine that may cause leg pain or numbness
  • Weight gain that may cause back problems

Proportionate dwarfism may result in smaller or less developed organs. Females with Turner syndrome could potentially have heart problems. Children with lower growth hormone levels or Turner syndrome could develop emotional or social issues due to delays in sexual development.

Pregnancy risks, such as respiratory issues, can occur in women with disproportionate dwarfism. They nearly all required a C-section to deliver their babies because the shape of their pelvis makes vaginal childbirth difficult.

People that are dwarfed may be called names or have a lack of understanding of their situation. To cope with their emotions, children with dwarfism who have low self-esteem can need emotional support from their parents.


Referenced on 2.3.2021:

  1. Texas Woman's University: “Dwarfism."
  2. Little People of America: “Frequently Asked Questions."
  3. Nemours Foundation: “Dwarfism."
  4. March of Dimes: “Quick References: Fact Sheets: Achondroplasia."
  5. The University of Delaware: “Dwarfism."
  6. Mayo Clinic: “Dwarfism.”
  7. Rady Children’s Hospital: “Genetic, Chromosomal, and Metabolic Conditions: Dwarfism.”

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