A 17-year-old boy presents with a 3-year history of insulin-dependent diabetes mellitus diagnosed at age 6, progressive bilateral vision loss with optic disc pallor, polyuria, and recent-onset hearing difficulty. Audiometry shows the pattern marked **B** in the diagram. Genetic testing confirms biallelic WFS1 mutations. Which of the following best explains the hearing loss pattern observed at **B**?
A. Bilateral symmetric high-frequency sensorineural hearing loss due to chronic endoplasmic reticulum stress and apoptosis of cochlear hair cells from wolframin deficiency
B. Unilateral low-frequency sensorineural hearing loss due to viral labyrinthitis affecting the cochlear apex
C. Progressive bilateral conductive hearing loss from chronic otitis media with ossicular erosion
D. Conductive hearing loss with air-bone gap secondary to ossicular fixation and middle ear effusion
Explanation
Why option 1 is correct
Wolfram syndrome (DIDMOAD) is an autosomal recessive neurodegenerative disorder caused by biallelic mutations in WFS1, which encodes wolframin—a transmembrane endoplasmic reticulum protein regulating calcium homeostasis and ER stress. Loss of wolframin causes chronic ER stress and apoptosis in multiple tissues, including cochlear and vestibular hair cells. The resulting sensorineural hearing loss is characteristically bilateral, symmetric, and high-frequency, appearing around age 16 and progressing over time. This pattern at B is pathognomonic for Wolfram syndrome and distinguishes it from other causes of deafness in the DIDMOAD tetrad. The audiogram pattern directly reflects the underlying pathophysiology of hair cell loss from ER stress-induced apoptosis.
Why each distractor is wrong
Option 2 (Conductive hearing loss with air-bone gap): This describes the pattern at C in the diagram. Conductive loss is not a feature of Wolfram syndrome; the hearing loss is sensorineural. Air-bone gaps are seen in otosclerosis, ossicular fixation, or middle ear disease—none of which are associated with WFS1 mutations.
Option 3 (Unilateral low-frequency SNHL from viral labyrinthitis): This describes the pattern at D (sloping unilateral SNHL). Wolfram syndrome causes bilateral, not unilateral, hearing loss. Viral labyrinthitis is an acute infectious process unrelated to the chronic ER stress pathophysiology of Wolfram syndrome.
Option 4 (Progressive bilateral conductive loss from chronic otitis media): Wolfram syndrome does not cause conductive hearing loss or chronic otitis media. The hearing loss is sensorineural, not conductive, and reflects primary hair cell dysfunction from wolframin deficiency, not middle ear pathology.
High-YieldNEET PG
DIDMOAD = Diabetes Insipidus + Diabetes Mellitus + Optic Atrophy + Deafness; the deafness is always bilateral high-frequency SNHL on audiometry, caused by WFS1-mediated ER stress in hair cells.
