A 6-year-old girl presents with a short neck, limited cervical spine mobility, and inability to abduct her right eye. Audiometry reveals bilateral severe sensorineural hearing loss. High-resolution temporal bone CT shows a Mondini deformity with enlarged vestibular aqueduct. The hearing loss pattern marked **A** in the diagram is consistent with Wildervanck syndrome. Which of the following best describes the embryological basis and inheritance pattern of this condition?

Question

Accepted Answer

A. Developmental field defect affecting neural crest and mesoderm-derived structures during weeks 3–7; polygenic or X-linked dominant inheritance with striking female predominance and male lethality. Wildervanck syndrome (cervico-oculo-acoustic syndrome) is defined by a triad of Klippel-Feil anomaly (cervical vertebral fusion), Duane retraction syndrome (CN VI hypoplasia with aberrant CN III innervation), and sensorineural or mixed hearing loss—often severe-to-profound as marked **A**. The condition arises from a developmental field defect affecting neural crest and mesoderm-derived structures during weeks 3–7 of embryogenesis. Critically, Wildervanck shows striking female predominance (>95% of cases), suggesting polygenic or X-linked dominant inheritance with male lethality, although true Mendelian inheritance has not been firmly established and most cases are sporadic. This inheritance pattern and embryological timing are pathognomonic for Wildervanck and distinguish it from other syndromic hearing loss conditions. (Cummings Otolaryngology 7e, Ch 198)

Answer

B. Developmental field defect affecting neural crest and mesoderm-derived structures during weeks 3–7; autosomal recessive inheritance with variable penetrance

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C. Defect in endoderm-derived structures during weeks 8–12; mitochondrial inheritance with maternal transmission only

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D. Mutation in the PAX3 gene affecting neural crest migration; autosomal dominant inheritance with equal gender distribution

Explanation

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