Understanding, Diagnosing, and Using Genetic Testing for Recessive Primary Microcephaly

Expert Reviewed By: ⁠Dr. Brandon Colby MD

Recessive Primary Microcephaly (MCPH) is a rare genetic disorder that affects the development of the brain, resulting in a significantly smaller head circumference compared to age and sex-matched peers. This condition can lead to intellectual disability and other neurological issues. Understanding the causes, diagnosis, and the role of genetic testing in MCPH is crucial for families affected by this disorder and medical professionals alike.

Understanding Recessive Primary Microcephaly

Primary Microcephaly is a congenital condition, meaning it is present at birth. The term ‘recessive’ refers to the inheritance pattern of the disorder. In order for an individual to be affected by MCPH, they must inherit two copies of the mutated gene, one from each parent. Parents who are carriers of the mutated gene typically do not show any signs or symptoms of the disorder.

There are several different genes associated with MCPH, and mutations in these genes can result in abnormal brain development. The affected genes are involved in various processes, such as cell division, DNA repair, and cell signaling. To date, more than 25 different genes have been identified as causative factors for MCPH, with more likely to be discovered in the future.

Diagnosing Recessive Primary Microcephaly

Diagnosis of MCPH typically begins with a thorough physical examination and assessment of the individual’s medical and family history. The most noticeable sign of MCPH is a significantly smaller head circumference, which can be measured and compared to standard growth charts. In some cases, prenatal ultrasound may detect signs of microcephaly before birth.

However, a small head circumference alone is not enough to confirm a diagnosis of MCPH. Further testing, such as magnetic resonance imaging (MRI) or computed tomography (CT) scans, may be used to examine the brain structure and identify any abnormalities. In addition, genetic testing can be a valuable tool in confirming a diagnosis and understanding the specific cause of MCPH in an individual.

The Role of Genetic Testing in Recessive Primary Microcephaly

Genetic testing can be a powerful tool in diagnosing and understanding MCPH. By analyzing an individual’s DNA, medical professionals can identify specific gene mutations that may be responsible for the disorder. This information can be helpful in several ways:

Confirming a Diagnosis

While physical examinations and imaging studies can provide valuable information, genetic testing can offer a definitive diagnosis of MCPH. Identifying the specific gene mutation responsible for the disorder can help to confirm the diagnosis and provide a better understanding of the underlying cause.

Guiding Treatment and Management

Although there is no cure for MCPH, understanding the specific genetic cause can help medical professionals develop a personalized treatment plan to address the individual’s unique needs. This may include therapies to support cognitive development, physical therapy to improve motor skills, and educational interventions to address learning challenges.

Family Planning and Carrier Testing

For families affected by MCPH, genetic testing can provide valuable information for future family planning. By identifying the specific gene mutation, couples can better understand their risk of having another child with the disorder. In addition, carrier testing can be offered to relatives of individuals with MCPH to determine their risk of passing on the mutated gene to their children.

Prenatal Testing

In some cases, prenatal testing may be available for couples at risk of having a child with MCPH. This can include chorionic villus sampling (CVS) or amniocentesis, which analyze fetal DNA to determine if the baby has inherited the mutated gene. This information can be helpful for families in making informed decisions about their pregnancy and preparing for the needs of a child with MCPH.

In conclusion, understanding, diagnosing, and using genetic testing for Recessive Primary Microcephaly is essential in providing the best possible care and support for individuals and families affected by this rare genetic disorder. As our knowledge of the genes involved in MCPH continues to grow, so too will our ability to diagnose, manage, and support those living with this challenging condition.

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)