Phelan-McDermid Syndrome

Description

Phelan-McDermid Syndrome is a rare genetic disorder that primarily affects development and behavior. Characterized by a range of symptoms, it often leads to significant challenges in communication, motor skills, and cognitive abilities. This blog explores the intricacies of Phelan-McDermid Syndrome, encompassing its signs and symptoms, causes, inheritance patterns, diagnosis, management approaches, and the journey of thriving with this condition. We will also delve into the genetic basis of the syndrome, highlighting the gene involved and its implications.

Genes Involved

Phelan-McDermid Syndrome is caused by a deletion or mutation in the SHANK3 gene, located on chromosome 22. The SHANK3 gene plays a crucial role in the development and function of synapses, the junctions where nerve cells communicate with each other.

Mutations or deletions in the SHANK3 gene disrupt the normal functioning of these synapses, leading to the characteristic developmental and behavioral challenges associated with Phelan-McDermid Syndrome.

Recognizing the Signs and Symptoms

Phelan-McDermid Syndrome presents with a wide spectrum of symptoms, varying in severity from person to person. Some common signs and symptoms include:

Developmental Delays: Children with Phelan-McDermid Syndrome often exhibit delays in reaching developmental milestones, such as walking, talking, and feeding.
Intellectual Disability: Individuals with this syndrome typically have intellectual disabilities, ranging from mild to severe.
Speech and Language Impairments: Communication challenges are prevalent, with difficulties in speaking, understanding language, and social interaction.
Hypotonia (Low Muscle Tone): Low muscle tone can affect motor skills and movement coordination.
Feeding Difficulties: Challenges with feeding, such as swallowing issues or poor appetite, can arise in early childhood.
Behavioral Issues: Individuals with Phelan-McDermid Syndrome may experience behavioral difficulties, including anxiety, hyperactivity, and repetitive behaviors.
Distinctive Facial Features: Some individuals may have characteristic facial features, such as a wide forehead, deep-set eyes, and a small chin.
Seizures: Seizures can occur in a subset of individuals with Phelan-McDermid Syndrome.
Sleep Disturbances: Sleep problems, such as insomnia or sleep apnea, can be common.
Gastrointestinal Issues: Gastrointestinal problems, including constipation or reflux, can also occur.
Skeletal Abnormalities: In some cases, individuals may have skeletal abnormalities, such as scoliosis (curvature of the spine).

It‘s important to note that the severity of symptoms can vary greatly among individuals with Phelan-McDermid Syndrome.

Causes

Phelan-McDermid Syndrome occurs due to a genetic alteration involving the SHANK3 gene. This alteration can take two main forms:

Deletion: A portion of the SHANK3 gene is missing, leading to a reduced or absent production of the SHANK3 protein.
Mutation: A change in the DNA sequence of the SHANK3 gene, which can affect the protein‘s structure or function.

In most cases, the genetic alteration occurs spontaneously, meaning it‘s not inherited from parents. However, in a small percentage of cases, the condition can be inherited from a parent who carries a deletion or mutation in the SHANK3 gene.

Inheritance/recurrence risk

Inheritance or Recurrence Risk

Phelan-McDermid Syndrome is primarily caused by a spontaneous deletion or mutation, meaning it is not usually inherited from parents. However, if a parent carries a deletion or mutation in the SHANK3 gene, there is a 50% chance of passing it on to their child.

In cases where Phelan-McDermid Syndrome is inherited, there is a higher risk of recurrence in subsequent pregnancies. If the deletion or mutation is identified in the family, genetic counseling can provide valuable information about the likelihood of recurrence and options for prenatal testing.

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