Which chromosomal anomaly is associated with ‘Cat eye syndrome’?
**Core Concept**
Cat eye syndrome is a rare genetic disorder characterized by congenital anomalies involving the eyes, ears, heart, and other systems. It is a result of a chromosomal anomaly involving the deletion of genetic material from chromosome 22.
**Why the Correct Answer is Right**
Cat eye syndrome is associated with a partial trisomy or tetrasomy of chromosome 22, specifically involving the q11.2-q12 region. This region contains several genes involved in development and growth, including the LIM domain kinase 1 (LIMK1) gene. The deletion or duplication of this region leads to the characteristic features of cat eye syndrome, including microphthalmia (small eyes), coloboma (a hole in one of the structures of the eye), and heart defects. The presence of extra genetic material or the absence of critical genes in this region disrupts normal development, leading to the characteristic anomalies.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not associated with Cat eye syndrome. Instead, it is related to a different chromosomal anomaly.
**Option B:** This option is incorrect because it is associated with a different condition, Edwards syndrome, which involves a different chromosomal region (chromosome 18).
**Option C:** This option is incorrect because it is not directly associated with Cat eye syndrome. While it may involve a chromosomal anomaly, it is not the correct one.
**Clinical Pearl / High-Yield Fact**
Cat eye syndrome is a rare but important condition to recognize in pediatric patients, as early diagnosis and management can improve outcomes. A high index of suspicion is necessary, as the condition may present with a range of subtle and non-specific features.
**Correct Answer:** C.