<prompt> The late features of kernicterus include all exceptHypotoniaSensorineural Hearing lossChoreoathetosisUpward Gaze palsy  <response>: Hypotonia is not a feature of kernicterus . Initial findings associated with kernicterus may vary from case to case, but often include lack of energy lethargy or drowsiness, poor feeding habits, fever, a shrill high-pitched cry, andor absence of ceain reflexes e.g., Moro reflex, etc.. Affected infants may eventually experience respiratory distress, mild to severe muscle spasms including those in which the head and heels are bent backward and the body bows forward opisthotonus, andor diminished muscle tone hypotonia. As an affected infants ages, other symptoms and physical findings may develop including delayed andor abnormal motions or motor development; convulsions or seizures; impaired ability to coordinate voluntary movements ataxia; abnormal muscle rigidity resulting in muscle spasms dystonia; slow, continuous, involuntary, writhing movements athetosis of the arms and legs limbs andor entire body; problems with sensory perception; lack of upward gaze; andor hearing loss. In some cases, affected infants may exhibit mental retardation and difficulty speaking dysahria. In most cases, the syndrome characteristic of kernicterus develops by three to four years of age. Reference: GHAI Essential pediatrics, 8th edition 