Deciphering Hemihypertrophy: Understanding, Diagnosing, and Using Genetic Testing

Expert Reviewed By: ⁠Dr. Brandon Colby MD

Understanding Hemihypertrophy

Hemihypertrophy, also known as hemihyperplasia, is a rare condition characterized by the asymmetric growth of one side of the body compared to the other. This can affect a single limb, the entire side of the body, or specific organs. The condition can be congenital, meaning it is present at birth, or it can develop over time. Hemihypertrophy can be associated with various syndromes and diseases, such as Beckwith-Wiedemann syndrome and craniosynostosis. However, in some cases, the cause remains unknown and is referred to as idiopathic hemihypertrophy.

Diagnosing Hemihypertrophy

Diagnosing hemihypertrophy can be challenging, as it can present in various forms and be associated with different genetic and epigenetic factors. In some cases, the condition can be identified during prenatal ultrasound examinations. However, it is more commonly diagnosed after birth through physical examination and medical imaging studies, such as X-rays, computed tomography (CT) scans, or magnetic resonance imaging (MRI).

Two studies, Manifestations and natural history of idiopathic hemihypertrophy: a review of eleven cases and Idiopathic congenital hemihypertrophy: a report on 6 cases, examined cases of idiopathic hemihypertrophy and found no genetic or aetiological factors. These studies recommend regular clinical surveillance for abdominal tumors and suggest orthopedic support for affected individuals.

Genetic Testing and Hemihypertrophy

Genetic testing can be helpful in identifying the underlying cause of hemihypertrophy, especially when it is associated with specific syndromes or diseases. However, in cases of idiopathic hemihypertrophy, genetic testing may not provide conclusive results.

Beckwith-Wiedemann Syndrome

Beckwith-Wiedemann syndrome is a genetic disorder that can cause hemihypertrophy, in addition to other symptoms such as macroglossia (enlarged tongue), abdominal wall defects, and an increased risk of developing tumors. Genetic testing can help identify the specific genetic or epigenetic cause of the syndrome, which can inform the appropriate tumor screening protocol for affected individuals. The article Tumor screening in Beckwith–Wiedemann syndrome—To screen or not to screen? discusses the challenges in adapting tumor screening protocols based on genetic and epigenetic causes.

Craniosynostosis

Craniosynostosis is a condition in which the bones of the skull fuse prematurely, leading to abnormal head shape and potential developmental issues. Hemihypertrophy can be associated with some craniosynostosis syndromes. Genetic testing can help identify the specific genetic cause of the syndrome, allowing for early intervention and appropriate management. The article Genetic Causes of Craniosynostosis: An Update reviews common craniosynostosis syndromes and novel genetic causes identified between January 2015 and December 2017.

Benefits of Genetic Testing

Genetic testing can be beneficial for individuals with hemihypertrophy and their families in several ways:

• Identifying the underlying cause of the condition, which can inform appropriate treatment and management strategies.
• Providing information on the risk of recurrence in future pregnancies, allowing families to make informed decisions about family planning.
• Offering the opportunity for early intervention and surveillance for associated health risks, such as tumor development.

Limitations of Genetic Testing

While genetic testing can be helpful in many cases, it is important to recognize its limitations:

• Genetic testing may not provide definitive answers in cases of idiopathic hemihypertrophy, as no specific genetic or aetiological factors have been identified in some cases.
• Genetic testing can be expensive and may not be covered by insurance, depending on the specific test and individual circumstances.
• Genetic counseling is recommended to help individuals and families understand the implications of genetic testing results and make informed decisions about their healthcare.

In conclusion, understanding, diagnosing, and using genetic testing for hemihypertrophy can provide valuable information for affected individuals and their families. However, it is important to recognize the limitations of genetic testing and seek appropriate medical guidance and support throughout the process.

About The Expert Reviewer

Dr. Brandon Colby MD is a US physician specializing in the personalized prevention of disease through the use of genomic technologies. He’s an expert in genetic testing, genetic analysis, and precision medicine. Dr. Colby is also the Founder of  and the author of ⁠⁠Outsmart Your Genes.

Dr. Colby holds an MD from the Mount Sinai School of Medicine, an MBA from Stanford University’s Graduate School of Business, and a degree in Genetics with Honors from the University of Michigan. He is an Affiliate Specialist of the American College of Medical Genetics and Genomics (⁠⁠ACMG), an Associate of the American College of Preventive Medicine (⁠⁠ACPM), and a member of the National Society of Genetic Counselors (⁠NSGC)