Achondroplasia: Inheritance, genetics, and the impact

Achondroplasia is a hereditary condition that causes short limbs by impairing the body’s capacity to convert cartilage to bone. Changes in the FGFR3 gene, which can be passed on from parents to children, cause the condition.

Short legs and limbs, an oversized head, and short fingers are all symptoms of achondroplasia. The ring and middle fingers of a person’s hand may diverge, giving each hand a three-pronged look.

Achondroplasia causes people to be small in stature. An adult’s average height is around 4 feet and 14 inches.

We’ll look at achondroplasia and genetics in this post, covering how the condition develops, how prevalent it is, and how people can detect whether they have the gene that causes it.

We also go through the symptoms of achondroplasia and how this type of dwarfism affects people’s lives.

Genetics and achondroplasia

Achondroplasia
Angela Ponce/Getty Images

As an autosomal dominant characteristic, achondroplasia can be passed down from parent to kid. This indicates that if only one parent passes on the mutated gene, the kid will be born with the condition.

Almost all occurrences of achondroplasia are caused by two particular mutations in the FGFR3 gene. This gene is in charge of telling the body how to create a certain protein. This protein aids in the development and maintenance of bone tissue.

In the majority of instances, the FGFR3 gene changes on its own in people who do not have achondroplasia. Around 80% of people born with the condition have average-sized parents. This mutated gene can exist without a person being aware of it.

If one or both parents have this type of dwarfism, their kid is likely to receive the high gene as well. A severe type of achondroplasia can occur in children who inherit two copies of the gene, one from each father.

Symptoms and signs

Achondroplasia is characterized by the following symptoms:

  • short fingers, with middle and ring fingers that may diverge
  • joint laxity, which means that their joints are very mobile
  • bowed legs
  • a prominent forehead
  • short stature
  • a head that is large, compared with their body
  • short arms and legs, especially the upper arms and thighs

What is the prevalence of achondroplasia?

The most prevalent kind of short-limbed dwarfism is achondroplasia, but it is uncommon in general. 1 in 10,000–30,000 people are affected by the condition.

Do people realize they carry the achondroplasia gene?

The majority of people who have the gene that causes achondroplasia are unaware that they have it. This is because, in the vast majority of cases, the gene changes spontaneously before being passed on from parent to kid.

People may not be aware of their gene status unless they obtain DNA testing before conceiving.

A doctor can typically tell if a person has achondroplasia by the physical indicators. DNA testing can confirm a diagnosis if a person has more than one hereditary condition or does not show the normal symptoms of the condition.

Testing for the FGFR3 gene

In 99 percent of people with achondroplasia, genetic testing may detect mutations in the FGFR3 gene. It can also detect the mutated gene in people who don’t have achondroplasia but wish to see whether they have it.

If a person is interested in genetic testing, they should:

  • want to conceive and want to be aware of any traits that they may pass on
  • are pregnant and want to screen for genetic conditions before delivery
  • have a child with possible signs of achondroplasia

Testing in adults

Any adult can request genetic testing to check whether they have a FGFR3 gene mutation. A doctor or technician obtains a sample of hair, blood, or saliva for the test.

The sample is then sent to a laboratory, where technicians examine proteins, DNA, and chromosomes for particular alterations. They look for specific alterations in the FGFR3 gene to diagnose achondroplasia.

Testing during pregnancy

Using an ultrasound scan during pregnancy, a doctor may be able to identify achondroplasia in a fetus. This might reveal symptoms of the condition, such as shorter humerus and femur bones.

The doctor may recommend genetic testing to confirm the diagnosis. Percutaneous umbilical blood sampling is a procedure that includes taking a sample of blood from the umbilical cord.

The fetus and the pregnant woman face a modest danger as a result of this sample. The operation can induce bleeding around the puncture site or a fetus’s heart rate to remain low for an extended period of time, both of which can be dangerous.

Children’s testing

Doctors can typically identify achondroplasia based on physical indicators, but if a child is extremely young or the symptoms are out of the ordinary, genetic testing may be recommended.

When a child is young, an early diagnosis might help physicians monitor for any linked issues, such as a spinal curvature. As a result, they will be treated and managed as quickly as feasible.

An X-ray may also be used to determine whether the “long bones,” such as the femur and humerus, have been shortened.

Impact of achondroplasia on a person’s life

Achondroplasia is usually not life threatening and does not require treatment. People with achondroplasia can live full, meaningful lives with the right treatment.

Everyday life

Achondroplasia does not hinder a person’s IQ or prohibit them from undertaking everyday activities like going to school, working, or starting a family.

Many of the difficulties people identify with dwarfism are caused by ableism rather than the condition itself.

Prejudice or discrimination against people with disabilities or people who are considered to have impairments is known as ableism. It is ubiquitous and can make daily living more difficult.

Many public venues, for example, are not planned with accessibility in mind. This makes navigating and using these locations more challenging for people with various physical limitations. This is a kind of unfairness since it is avoidable.

A lack of inclusion in design might be challenging for people with achondroplasia:

  • reaching things
  • finding accessible bathrooms
  • driving

Discrimination against people with dwarfism can have a negative influence on their mental health.

Every person, however, is unique, and so are their achondroplasia experiences. On the Little People of America website, people may discover information on modifying their homes, tools for caretakers and instructors, and first-hand experiences of what it’s like to be a dwarf.

Long-term health

Certain health issues are more likely in people with achondroplasia. Many of these can be treated or managed by doctors.

The following are some of the most prevalent orthopedic conditions:

  • compression of the bones at the base of the skull
  • obstructive sleep apnea
  • chronic pain
  • a small ribcage, which may cause problems with the lungs or airways
  • a curved spine, such as scoliosis or kyphosis
  • narrowing of the spinal column, or spinal stenosis

Many people with achondroplasia also have hydrocephalus, which is a condition in which there is fluid on the brain. Although a modest amount is typically not hazardous, the condition can be dangerous. Doctors can use a shunt to drain the extra fluid in this scenario.

Conclusion

Achondroplasia is a kind of dwarfism characterized by short limbs. It is caused by inheriting a FGFR3 gene mutation from one or both parents. In the vast majority of cases, the parents are unaffected.

Many people who have the FGFR3 gene changed are unaware of it. It can be detected by a clinician through genetic testing performed throughout infancy or maturity, even during pregnancy. X-rays and ultrasound scans may also be used to assist in the diagnosis.

Certain issues are more common in people with achondroplasia, but physicians can treat them or lessen their impact.

Sources:

  • https://www.genome.gov/Genetic-Disorders/Achondroplasia
  • https://medlineplus.gov/genetics/condition/achondroplasia/
  • https://www.lpaonline.org/faq-
  • https://www.medicalnewstoday.com/articles/achondroplasia-genetics
  • https://pediatrics.aappublications.org/content/145/6/e20201010
  • https://publications.aap.org/aapnews/news/7360

Back to top button