U01.01.059 Cri-du-chat syndrome

Cri-du-chat syndrome, also known as “cry of the cat,” is a rare genetic disorder caused by a congenital deletion on the short arm of chromosome 5 (5p−), resulting in the absence of critical genes.

Genetic Cause

Chromosome Abnormality: Deletion on the short arm of chromosome 5 (5p−).
Karyotype: 46,XX or XY, 5p−.

Clinical Findings

The clinical presentation of Cri-du-chat syndrome includes a variety of physical, cognitive, and developmental abnormalities. Key findings include:

Clinical Feature	Description
Microcephaly	Smaller than average head size.
Intellectual Disability	Moderate to severe cognitive impairments.
High-Pitched Crying	Characteristic “cry of the cat” that sounds like meowing.
Epicanthal Folds	Skin folds at the inner corner of the eyes.
Cardiac Abnormalities	Often a ventricular septal defect (VSD).

Key Points to Remember

Mnemonic: Cri-du-chat = “cry of the cat,” describing the high-pitched cry, which is a hallmark of the disorder.
Genetic Deletion: Deletion of the 5p chromosome arm.
Physical Manifestations: Includes microcephaly, epicanthal folds, and cardiac defects (VSD).
Cognitive Effects: Moderate to severe intellectual disability.
High-Pitched Cry: A distinctive feature of this syndrome that may be noted in newborns.

This information is essential for understanding the clinical manifestations and genetic basis of Cri-du-chat syndrome for the USMLE Step 1.

USMLE Step 1 Review Series

Curriculum

U01.01.059 Cri-du-chat syndrome

Genetic Cause

Clinical Findings

Key Points to Remember

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