How is 22q13 deletion / Phelan-McDermid Syndrome diagnosed?

22q13 deletion syndrome, also known as Phelan-McDermid Syndrome (PMS), is a rare genetic disorder caused by the deletion or loss of a small piece of chromosome 22. This syndrome is characterized by a wide range of symptoms including developmental delays, intellectual disability, speech and language impairments, autism spectrum disorder, and physical abnormalities.

Diagnosing 22q13 deletion syndrome can be challenging due to its rarity and the variability of symptoms among affected individuals. However, there are several key steps and tests involved in the diagnostic process:

1. Clinical Evaluation: The first step in diagnosing 22q13 deletion syndrome is a thorough clinical evaluation by a healthcare professional. This typically involves a detailed medical history review, physical examination, and assessment of developmental milestones. The healthcare provider will look for characteristic features associated with the syndrome, such as low muscle tone, delayed speech, and behavioral issues.

2. Genetic Testing: Genetic testing plays a crucial role in confirming the diagnosis of 22q13 deletion syndrome. The two main types of genetic tests used are:

• Chromosomal Microarray Analysis (CMA): CMA is the most commonly used test for detecting chromosomal abnormalities, including deletions. It can identify small deletions or duplications in the DNA, including the deletion on chromosome 22 associated with 22q13 deletion syndrome.


• Fluorescence In Situ Hybridization (FISH): FISH is another genetic test that can specifically detect the deletion on chromosome 22. It uses fluorescent probes to bind to specific DNA sequences and visualize the presence or absence of the deletion.

3. Array Comparative Genomic Hybridization (aCGH): This test is similar to CMA and can also detect chromosomal abnormalities, including the deletion on chromosome 22. It provides high-resolution analysis of the genome and can identify smaller deletions or duplications that may be missed by other tests.

4. Genetic Counseling: Genetic counseling is an essential part of the diagnostic process for 22q13 deletion syndrome. Genetic counselors are trained professionals who can help individuals and families understand the genetic basis of the syndrome, discuss the implications of the diagnosis, and provide guidance regarding available resources and support.

5. Additional Evaluations: In addition to genetic testing, further evaluations may be recommended to assess the specific symptoms and associated conditions of the individual. These may include:

• Developmental and Cognitive Assessments: These evaluations involve standardized tests to assess the individual's developmental progress, intellectual abilities, and cognitive functioning.


• Speech and Language Assessments: Speech and language pathologists can evaluate the individual's communication skills, including speech production, receptive and expressive language abilities, and social communication.


• Behavioral and Psychological Assessments: Psychologists or psychiatrists may conduct assessments to evaluate behavioral issues, social skills, and emotional well-being.


• Medical Imaging: Imaging techniques such as magnetic resonance imaging (MRI) or computed tomography (CT) scans may be used to assess any physical abnormalities or structural brain changes.

Early diagnosis of 22q13 deletion syndrome is crucial for appropriate management and intervention. It allows for early intervention services, tailored educational programs, and access to support networks. Additionally, early diagnosis enables families to connect with other individuals and families affected by the syndrome, fostering a sense of community and shared experiences.

In conclusion, diagnosing 22q13 deletion syndrome involves a comprehensive evaluation by healthcare professionals, genetic testing (such as CMA, FISH, or aCGH), genetic counseling, and additional assessments to evaluate specific symptoms and associated conditions. Early diagnosis is essential for providing appropriate support and interventions to individuals with 22q13 deletion syndrome and their families.