The Historical Context: Helen Keller

Helen Keller is widely recognized for her remarkable life lived with combined hearing and visual impairment. What is less commonly known is that her condition resulted from a severe childhood infection. In contrast, in the modern era, a comparable dual sensory impairment affects thousands of adolescents worldwide, not due to infection, but due to pathogenic variants in specific genes. This condition is known as Usher syndrome, a hereditary disorder caused by alterations in the DNA sequence.

Adolescent Lifestyle: A Potential Source of Diagnostic Delay

Contemporary adolescents frequently engage in prolonged gaming or regular use of personal audio devices at high volumes. When symptoms such as difficulty navigating in low-light environments or progressive hearing loss emerge, these are often attributed to lifestyle factors. Hearing deterioration is commonly presumed to be noise-induced, while impaired mobility in the dark is dismissed as inattentiveness or clumsiness.

However, medical evidence indicates that such assumptions may obscure the early clinical manifestations of Usher syndrome. In numerous cases, hearing loss initially diagnosed as Noise-Induced Hearing Loss (NIHL) represents the early auditory phenotype of this inherited disorder.

Clinical Classification: Three Major Types of Usher Syndrome

Usher syndrome presents with clinical heterogeneity and is classified into three main types:

• Type 1 is the most severe form. Affected individuals are born with profound congenital hearing loss and significant vestibular dysfunction, often resulting in delayed independent walking. Progressive retinal degeneration typically begins in early childhood, often before the age of ten.
• Type 2 is the most common and frequently underdiagnosed form. Individuals are born with moderate-to-severe hearing loss but normal vestibular function. Because early development appears typical, diagnosis is often delayed until adolescence, when symptoms of nyctalopia (night blindness) and peripheral visual impairment become apparent.
• Type 3 is rare and characterized by progressive hearing and vision loss that begins in late adolescence or early adulthood, with considerable variability in severity and progression.

Diagnostic Pathways: Reactive versus Proactive Approaches

The timing of diagnosis has a substantial impact on long-term clinical management and psychosocial preparedness.

1. Conventional Diagnostic Pathway (Reactive):

• Childhood: Hearing impairment is identified, and management focuses exclusively on auditory rehabilitation.
• Adolescence: Declining hearing acuity and impaired mobility in low-light conditions are attributed to environmental or behavioral factors.
• Early adulthood: Progressive visual field constriction prompts ophthalmologic evaluation, leading to a delayed diagnosis of Usher syndrome—often 10–15 years after initial symptoms.

2. Contemporary Diagnostic Pathway (Proactive with cWES):

• Early identification: Genetic evaluation is recommended at the onset of unexplained or congenital hearing loss.
• Definitive diagnosis:Clinical Whole Exome Sequencing (cWES) enables detection of pathogenic variants (e.g., USH2A) prior to the onset of visual symptoms.
• Outcome: Early diagnosis allows families and clinicians to anticipate disease progression and implement appropriate medical, educational, and psychological planning.

Clinical Indicators for Parental Awareness

Further evaluation should be considered in children with hearing loss who also exhibit:

• Night vision difficulties: Fearfulness or impaired navigation in dimly lit environments
• Light sensitivity: Excessive glare sensitivity to headlights or bright sunlight
• Peripheral vision impairment: Frequent collisions with objects or difficulty navigating familiar spaces
• Vestibular signs: Delayed motor milestones or instability on uneven surfaces

Clinical Whole Exome Sequencing as Proactive Way

Assessment of hearing impairment should not be isolated from other sensory and neurological findings. When auditory symptoms coexist with visual or balance-related abnormalities, genetic testing using cWES represents the current diagnostic gold standard, providing diagnostic certainty and enabling informed, long-term clinical planning for affected individuals and their families.