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Unformatted text preview: t with vitamin D, which normally cures
rickets. Example of an
X-Linked (Sex-linked) Dominant Trait
• Results from a defective transport of phosphate, especially in
cells of the kidneys.
• Affected individuals excrete large amounts of phosphate in
their urine, resulting in low deposition of minerals in the
• Males are often more severely affected than females - why? Y-linked Traits
• Father to son
• Not usually found in
• Very few genes on
the Y chromosome Major Characteristics of Different Types of
Inheritance Aneuploidy: Introduction
Trisomy 21 results in Down Syndrome
• 1866: John Langdon Down, a physician at Earlwood Asylum in
Surrey, England, noticed a resemblance among many of his
intellectually disabled patients. • Common characteristics: broad ﬂat faces, thick tongues, small
noses, oval shaped eyes • The disorder he described is now called Down Syndrome. Introduction:
Trisomy 21 results in Down Syndrome...
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