A 6-year-old boy with mental retardation has recently been d

Discussion in 'USMLE Step 2 CK' started by Guest, Dec 1, 2009.

  1. Guest

    Guest Guest

    A 6-year-old boy with mental retardation has recently been diagnosed with Fragile X syndrome. His 9-year-old sister appears to be of normal intelligence but has symptoms of attention deficit hyperactivity disorder (ADHD). What is the first test that is indicated in her work-up for ADHD?

    A. EEG
    B. Cytogenetic testing
    C. MRI
    D. Intelligence quotient (IQ) test
    E. Urine for metabolic screen
  2. Guest

    Guest Guest

    B is answer.

    Cytogenetic testing should be performed on all sisters of males with Fragile X. Heterozygous females frequently have developmental and behavioral problems such as ADH

    D. They may also have borderline or mild mental retardation.

    An EEG (choice A) is likely to be normal, and unless there are signs or symptoms suggestive of a seizure disorder, it would not be indicated.

    ADHD is a clinical diagnosis and no neuroimaging tests such as MRI (choice C) will be useful in making the diagnosis of ADHD.

    IQ testing (choice D) may be helpful in school placement, but it is not the first test to be ordered.

    Urine for metabolic screening (choice E) is used to detect rare inborn errors of metabolism. It would be indicated in cases of failure to thrive, seizures, and sepsis. Many inborn errors of metabolism are associated with severe mental retardation.

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