Is Pectus Carinatum Genetic?

Although it is not uncommon, most people have not heard of the condition known as pectus carinatum or pigeon chest. So what exactly is pectus carinatum? What are its genetic causes and the impact of other influences? And most importantly, what are the chances of your child inheriting and developing this condition? This article will answer all of these questions about the genetic basis of pectus carinatum. 

What Is Pectus Carinatum?

Pectus carinatum is a structural condition where part of the breastbone sticks out from the rest of the chest. This arises due to the breastbone cartilage growing excessively. It is congenital, meaning that it is present from birth. However, it does not become evident in most sufferers until they reach their late pre-teen or early teen years. At this age, the body is rapidly growing due to puberty, and any abnormalities in breastbone growth become more evident. 

Pectus carinatum can vary widely in its severity, as well as its presentation. Some people have symmetric protrusion across both sides of the chest, while others may show protrusion on only one side (asymmetric). In addition to the protrusion of the breastbone, other signs of pectus carinatum include: 

• Poor posture (rounded shoulders or hunched back)
• Excessive curvature of the spine
• Flaring of the ribs (protrusion out from the chest). This occurs quite commonly in association with pectus carinatum. 
• Tachycardia (having an unusually fast heart rate)
• Feeling fatigued, lethargic, or short of breath. This occurs in up to 25% of people with the condition. 
• Chest pain (in rare instances)

Pectus carinatum may occur alone (isolated pectus carinatum) or as a result of other syndromes/conditions, including trisomy 18, trisomy 21 (Down syndrome), homocystinuria, Marfan syndrome, Ehlers-Danlos syndrome, Noonan syndrome, multiple lentigines syndrome, Morquio syndrome, and Osteogenesis imperfecta. 

Most cases of pectus carinatum are relatively mild and can be treated with non-surgical treatment such as orthotic bracing. However, the most severe cases of this condition may require corrective surgery.

Is Pectus Carinatum Genetic?

The exact causes of pectus carinatum are not fully understood and are still being researched by doctors and scientists. Genetic inheritance appears to be responsible in at least 25% of patients.[1]

In cases where isolated pectus carinatum is inherited, it usually seems to be autosomal dominant (meaning that it can pass from only one parent onto their child) and less commonly autosomal recessive.[2] 

However, genetics is not the only cause responsible for pectus carinatum. As previously mentioned, genetics can only be attributed as the primary cause in around 25% of patients. The remaining variation is attributed to environmental factors and random chance.[3] This type of inheritance is known as multifactorial inheritance. 

What Genes are Responsible for Pectus Carinatum?

The genes responsible for causing isolated cases of pectus carinatum are not known in most instances. 

However, many genes responsible for other syndromes associated with pectus carinatum are known. For example, mutations in the FBN1 gene are commonly the cause of Marfan syndrome, which usually results in a pectus deformity. Similarly, mutations in the PTPN11 or SOS1 genes are commonly found in patients with Noonan syndrome. Tests are available for mutations in many of these genes. 

How Does Pectus Carinatum Run in Families?

Pectus carinatum does sometimes run in families, meaning that it can be passed onto the child of someone with this condition. However, the risks depend on the cause of pectus carinatum. If it is due to an associated genetic condition such as Marfan syndrome, then there is a 50% chance that it will be passed on to the child. However, in cases of isolated pectus carinatum, the risks are much lower. 

The advice of geneticists is that it is very hard to calculate the chance that pectus carinatum will be passed on from someone who has pectus carinatum to their child. In general, the chances will be somewhat higher than for the child of someone who does not have pectus carinatum, but will still be quite low. 

Can I Get a Genetic Test for Pectus Carinatum?

There are currently no genetic tests available specifically for pectus carinatum. However, genetic tests are available to check for some of the conditions and syndromes that are associated with pectus carinatum, such as Marfan syndrome and Noonan syndrome. Your health professional will be able to advise which of these tests are recommended. 

What Are the Odds of My Child Inheriting Pectus Carinatum?

Pectus carinatum is moderately common, with one study reporting its occurrence an average of once every 1,500 births (0.07%).[4] However, as discussed previously, the risks may vary with genetics, location, and other environmental factors. One study from Brazil reported an incidence of 0.7% in middle schoolers.[5] Similarly, an incidence rate of 0.6% has been reported for middle school students from Turkey.[6] These numbers indicate the incidence of pectus carinatum occurring in the children of parents without a pectus condition. However, if the pectus carinatum is due to an associated genetic condition such as Marfan syndrome, there is a 50% chance that it will be passed on. For isolated cases of pectus carinatum, the chance of passing it on to your child is much lower. 

One fact that is well documented is that cases of pectus carinatum are much more common in males. Some studies have reported rates up to 9 times higher in males.[7] However, most clinical studies have shown that the odds of developing pectus carinatum are 4 to 5 times higher in males compared to females.[3,8] 

Conclusion

Does your child suffer from pectus carinatum? Here at Dakota Brace, our aim is to provide the best possible treatment for pectus carinatum, at an affordable cost.

Arrange a free consultation with one of our health professionals and $75 off your first order!

References

1. Shamberger, R. C. (1996). Congenital chest wall deformities. Current Problems in Surgery, 33(6), 469-542.
2. Heithaus, J. L., Davenport, S., Twyman, K. A., Torti, E. E., & Batanian, J. R. (2014). An intragenic deletion of the gene MNAT1 in a family with pectus deformities. American Journal of Medical Genetics Part A, 164(5), 1293-1297.
3. Cobben, J. M., Oostra, R. J., & van Dijk, F. S. (2014). Pectus excavatum and carinatum. European Journal of Medical Genetics, 57(8), 414-417.
4. Robicsek F, Watts LT. Pectus carinatum. Thorac Surg Clin. 2010;20:563–74.
5. Westphal, F. L., Lima, L. C. D., Lima Neto, J. C., Chaves, A. R., Santos Júnior, V. L. D., & Ferreira, B. L. C. (2009). Prevalência de pectus carinatum e pectus excavatum em escolares de Manaus. Jornal Brasileiro de Pneumologia, 35, 221-226.
6. Coskun, Z. K., Turgut, H. B., Demirsoy, S., & Cansu, A. (2010). The prevalence and effects of pectus excavatum and pectus carinatum on the respiratory function in children between 7–14 years old. The Indian Journal of Pediatrics, 77(9), 1017-1019.
7. Özkaya, M., & Bilgin, M. (2018). Minimally invasive repair of pectus carinatum: a retrospective analysis based on a single surgeon’s 10 years of experience. General Thoracic and Cardiovascular Surgery, 66(11), 653-657.
8. Abdullah F, Harris J (2016) Pectus excavatum: more than a matter of aesthetics. Pediatr Ann, 45:e403–e406.