Identification of a cat eye syndrome using DNA sequence dosage analysis

Area of Science:

• Genetics
• Human Chromosome Analysis
• Medical Diagnostics

Background:

• Cat Eye Syndrome (CES) is a rare genetic disorder characterized by specific physical abnormalities.
• Diagnosis typically relies on identifying characteristic chromosomal abnormalities.
• Phenotypic variability can complicate diagnosis.

Observation:

• A patient presented with a karyotype revealing a small supernumerary bisatellited chromosome.
• Initial banding analysis suggested a fragment of chromosomes 13, 15, 21, or 22.
• The patient did not exhibit the classic CES phenotype prior to intensive surgery.

Findings:

• Southern blot analysis confirmed DNA amplification in the 22q11 region.
• This genetic finding is strongly indicative of Cat Eye Syndrome.
• The supernumerary chromosome is likely the source of the 22q11 amplification.

Implications:

• This case highlights the potential for CES to present atypically, even in the absence of a clear phenotype.
• Genetic testing, including karyotyping and Southern blot, is crucial for accurate CES diagnosis.
• Understanding chromosomal anomalies like 22q11 amplification is vital for genetic counseling and patient management.