The human genome is a complex tapestry of chromosomes and genes. Each one influences our development and overall well-being. Chromosome 15 — one of the 23 chromosomes, which includes one copy each from the maternal and paternal sides — harbors a myriad of genes involved in various functions of the body. This chromosome is unique from most of our others because some genes on Chromosome 15 are only turned on from the paternal copy and some from the maternal’s copy. When genetic abnormalities occur within this chromosome, they can lead to a group of neurodevelopmental issues collectively known as Chromosome 15 disorders. This blog shares an overview of these rare genetic disorders, including three examples that shed light on the challenges patients and their families may face.
Chromosome 15 Disorders: Overview and Examples
Chromosome 15 disorders encompass a range of genetic conditions that result from deletions, duplications or other mutations within the genes located on this specific chromosome. These disorders can manifest in numerous ways, affecting an individual’s physical, cognitive and behavioral functions. Diagnosis typically happens when patients are infants or young children. However, the severity and symptoms of Chromosome 15 disorders vary widely, making diagnosis and management difficult. Here are three examples of these complex multi-system disorders.
- Prader-Willi Syndrome: Prader-Willi syndrome (PWS) is characterized by the loss of working copies of a collection of genes on the paternal copy of Chromosome 15 … most often caused by a deletion of a part of the chromosome. Individuals with PWS often are diagnosed at birth due to weak muscles and lack of interest in feeding. They face challenges such as developmental delay, intellectual disabilities, behavioral concerns and a constant hunger that can lead to excessive weight gain.
- Angelman Syndrome: Angelman syndrome is caused by the missing expression of gene UBE3A on the maternal copy of Chromosome 15. Features include developmental delays such as speech with many individuals remaining nonverbal, disordered sleep, and characteristic behaviors that include a distinctive happy demeanor. From an early age, these individuals may struggle with movement due to balance and coordination problems. They may also be prone to seizures that may be difficult to treat. People with Angelman require lifelong expert care.
- Dup15q Syndrome: Dup15q syndrome is characterized by an extra copy (duplication) of a segment on the maternal copy of Chromosome 15. This rare condition can result in a spectrum of developmental delays, intellectual disabilities and epilepsy. Patients with Dup15q syndrome often have autism spectrum disorder (ASD). Decreased muscle tone and impaired movements.
Diagnosis and Management of Chromosome 15 Disorders
Understanding the causes of these disorders is crucial for early diagnosis, intervention and support. Due to the complexity of Chromosome 15 disorders, providers must have specific expertise to provide comprehensive and coordinated care. In addition to primary care physicians, this team may include dietitians, orthopedic specialists, medical geneticists, neurologists, occupational, physical, and speech therapists, mental health experts, sleep specialists, endocrinologists and gastroenterology experts.
Advanced genetic testing and evaluation can result in a more accurate prognosis of what symptoms and behaviors to plan for over time. This testing and evaluation will allow providers to offer targeted interventions and support. Families may also learn about the likelihood of recurrence in future children.
Because many providers are relatively unfamiliar with these conditions, collaborating with a medical geneticist and special care physician with expertise in these disorders is invaluable. These collaborations help providers know what to watch for, labs to consider, resources to recommend, and best practices for health management and care based on the latest research.
As genetic and medical researchers delve deeper into the intricacies of Chromosome 15 and its associated disorders, scientific advancements offer hope for improved management and, eventually, potential treatments. Clinical trials are also underway that may change how we think about and treat these disorders. Geneticists specializing in these conditions can direct patients and families to these ongoing and upcoming clinical trials.
To connect with a medical geneticist about the diagnosis and management of Chromosome 15 disorders or another genetic disorder, contact SequenceMD to see how we can support you and your family.