Two siblings, a girl and a boy, of consanguineous parents were thought to have the Rubinstein-Taybi syndrome. They have mental, motor, and growth retardation, microcephaly, "odd" but characteristic facial features, ocular abnormalities, and high arched palate. The boy has cryptorchidism. Broad thumbs and first toes described in all previously reported cases are absent clinically and are questionable radiologically. Findings of broad thumbs and first toes should not be considered essential for diagnosis.
Cause of the syndrome is unknown. Because it occurs in siblings of closely consanguineous parents, genetic cause is suggested. Autosomal recessive inheritance pattern is favored.
Conventional light microscopy and high resolution light microscopy of muscle revealed denervation atrophy. Electron microscopy revealed changes in glycogen, sarcoplasmic reticulum profile, contractile apparatus, and intramuscular nerves. These are not yet reported in this syndrome.
Der Kaloustian VM, Afifi AK, Sinno AA, Mire J. The Rubinstein-Taybi Syndrome: A Clinical and Muscle Electron Microscopic Study. Am J Dis Child. 1972;124(6):897–902. doi:10.1001/archpedi.1972.02110180099014
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