A 2-year-old boy has intellectual disability and a 'cat cry' at birth. Chromosomal microarray shows a deletion of the short arm of chromosome 5 (del 5p). This is Cri-du-chat syndrome. The 'cat-like' cry is caused by:

• A Abnormal neurological control of laryngeal musculature
• B Tracheomalacia causing dynamic airway collapse
• C Laryngeal hypoplasia and a small, narrow larynx ✓
• D Vocal cord paralysis from CN X injury

Explanation

The characteristic high-pitched mewing cry in cri-du-chat syndrome is caused by laryngeal hypoplasia — the larynx is small, narrow, and develops abnormally due to haploinsufficiency of critical genes in the deleted 5p15.3 region. The cry resembles a mewing cat. Other features include microcephaly, hypertelorism, epicanthal folds, low-set ears, and severe intellectual disability. Neurological dysregulation of laryngeal control may also contribute, but the primary structural cause is laryngeal hypoplasia. The deletion is usually de novo (~85%) and rarely inherited.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.