What is the Difference Between Prader Willi and Angelman Syndrome

The key difference between Prader Willi and Angelman syndrome is that Prader Willi syndrome is caused by the loss of function of paternally expressed genes in a region of chromosome 15 due to a deletion or uniparental disomy while Angelman syndrome is caused by the loss of function of maternally expressed genes in a region of chromosome 15 due to a deletion or uniparental disomy.

Prader Willi and Angelman syndromes are two genetic disorders that can occur due to the loss of a chromosomal region due to deletion. They are also associated with uniparental disomy, which refers to the situation in which two copies of a chromosome come from the same parent instead of one copy coming from the mother and the other copy coming from the father. Furthermore, they are also known as genetic (or genomic) imprinting disorders.

CONTENTS

1. Overview and Key Difference
2. What is Prader Willi Syndrome
3. What is Angelman Syndrome
4. Similarities – Prader Willi and Angelman Syndrome
5. Prader Willi vs Angelman Syndrome in Tabular Form
6. Summary – Prader Willi vs Angelman Syndrome

What is Prader Willi Syndrome?

Prader Willi syndrome is a genetic disorder caused by the loss of function of paternally expressed genes in a region of chromosome 15 due to a deletion or uniparental disomy. In Prader Willi syndrome, about 74% of cases occur when part of the father’s chromosome 15 is deleted. In another 25% of cases, the affected person has two copies of the maternal chromosome 15 and lacks a paternal copy. As parts of the chromosome from the mother are turned off through imprinting, they end up with no working copies of certain genes.

The symptoms of infants who suffer from Prader Willi syndrome may include poor muscle tone, distinct facial features, poor sucking reflex, generally poor responsiveness, and underdeveloped genitals. The signs and symptoms of early childhood to adulthood may include food craving and weight gain, underdeveloped sex organs, poor growth and physical development, cognitive impairment, delayed motor development, speech problems, behavioural problems, sleep disorders, scoliosis, hip problems, reduced saliva flow, vision problems, problems in regulation temperature, and lack of pigmentations causing hair, eye, skin to become pale.

This genetic disorder can be diagnosed through physical examinations, blood tests, and genetic tests. Furthermore, children with Prader Willi syndrome are treated through good nutrition, human growth hormone treatment, sex hormone treatment, weight management, treatment for sleep disturbances, various therapy, behavioural therapy, mental health care, and other treatments for vision problems, hypothyroidism, diabetes, scoliosis, etc. Many adults with this genetic disorder live in residential care facilities, which enable them to eat a healthy diet, live safely, work, and enjoy leisure activities.

What is Angelman Syndrome?

Angelman syndrome is a genetic disorder caused by the loss of function of maternally expressed genes in a region of chromosome 15 due to a deletion or uniparental disomy. Angelman syndrome is due to the lack of function of a region of chromosome 15 caused by a deletion or new mutation (deletion or mutation of UBE3Agene on chromosome 15). Occasionally, it happens due to inheriting two copies of chromosome 15 from a person’s father and non from the mother. As the father’s copies are inactivated by genomic imprinting, no functional version of the gene remains.

The signs and symptoms of this condition may include development delays: no crawling or babbling at 6 to 12 months, intellectual disability, no speech, difficulty walking,  frequent smiling and laughter, happy, excitable personality, sucking or feeding difficulty, trouble going to sleep and staying asleep, seizures usually between 2 and 3 years of age, stiff or jerky movements, small head size with flatness in the back of the head, tongue thrusting, hair, skin, and eyes are lighter in colour, unusual behaviours such as hand flapping and arms uplifted while walking, sleep problems, and curved spine.

Moreover, this genetic disorder can be diagnosed through physical examinations, blood tests, speech tests, parental DNA pattern tests, missing chromosomes tests, and gene mutation tests. Furthermore, treatment options for Angelman syndrome include anti-seizure medications, physical therapy, communication and speech therapy, behavioural therapy and medications and sleep training, dietary changes, and medications.

What are the Similarities Between Prader Willi and Angelman Syndrome?

• Prader Willi and Angelman syndromes are two genetic disorders that can be due to the loss of the chromosomal region due to deletion or uniparental disomy.
• They are also known as genetic imprinting disorders.
• Both disorders are not inherited.
• These disorders are caused due to problems in chromosome 15.
• Men and women are equally affected by both disorders.
• They are treatable through supportive care.

What is the Difference Between Prader Willi and Angelman Syndrome?

Prader Willi syndrome is a genetic disorder caused by loss of function of paternally expressed genes in a region of chromosome 15 due to a deletion or uniparental disomy, while Angelman syndrome is a genetic disorder caused by loss of function of maternally expressed genes in a region of chromosome 15 due to a deletion or uniparental disomy. Thus, this is the key difference between Prader Willi and Angelman syndrome. Furthermore, the disease prevalence for Prader Willi syndrome is one in 15000 people, while the disease prevalence for Angelman syndrome is one in 12000 to 20000 people.

The below infographic presents the differences between Prader Willi and Angelman syndrome in tabular form for side by side comparison.

Summary – Prader Willi vs Angelman Syndrome

Prader Willi and Angelman syndromes are two rare genetic disorders. Prader Willi syndrome is a genetic disorder caused by the loss of function of paternally expressed genes in a region of chromosome 15 due to a deletion or uniparental disomy. Meanwhile, Angelman syndrome is a genetic disorder caused by the loss of function of maternally expressed genes in a region of chromosome 15 due to a deletion or uniparental disomy. So, this is the key difference between Prader Willi and Angelman syndromes.

Reference:

1. “Prader-Willi Syndrome.” An Overview | ScienceDirect Topics.
2. “Angelman Syndrome.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 1 Mar. 2022.

Image Courtesy:

1. “Prader-WilliBMC” By Cataletto M, Angulo M, Hertz G, Whitman B. – NCBI (CC BY 2.5) via Commons Wikimedia
2. “5-year-old Mexican girl with Angelman syndrome (cropped)” By Yokoyama-Rebollar E, Ruiz-Herrera A, Lieberman-Hernández E, Del Castillo-Ruiz V, Sánchez-Sandoval S, Ávila-Flores SM, Castrillo JL – Mol Cytogenet (2015) – Angelman Syndrome due to familial translocation: unexpected additional results characterized by Microarray-based Comparative Genomic Hybridization. (CC BY 4.0) via Commons Wikimedia