Genetic Disorders

Down’s Syndrome Caused by non-disjunction of the 21st chromosome. This means that the individual has a trisomy (3 copies of the 2lst chromosomes).

Down’s Syndrome or Trisomy 21 What kind of picture is this?

Symptoms of Down Syndrome Upward slant to eyes. Distinctive facial features Low muscle tone Usually mild to moderate mental retardation. In some cases, mental issues are severe.

Kleinfelter’s syndrome XXY Non-disjunction of the X chromosome. Males with some development of breast tissue normally seen in females. Little body hair is present, and such person are typically tall, have small testes. Infertility Evidence of mental retardation may or may not be present.

Kleinfelter’s syndrome

Turner’s Syndrome

Sickle Cell Anemia Autosomal Recessive Results in crescent or “sickle” shaped red blood cells. Homozygous recessive condition is fatal. Heterozygous condition provides some protection against malaria.

Cystic Fibrosis (CF) Autosomal Recessive Cause: deletion of only 3 bases on chromosome 7 Fluid in lungs, potential respiratory failure Common among Caucasians…1 in 20 are carriers

Tay-Sachs disease Autosomal recessive Central nervous system degrades, ultimately causing death. – Normally before 3 years old Most common among people of Jewish, eastern Europe descent.

Hemophilia, the royal disease Recessive – Sex linked (on the X chromosome) One can bleed to death with small cuts. Known as the royal disease (very important in Russian history)

Huntington’s Disease Autosomal Dominant Rare – most common among white Europeans Brain tissue is destroyed leading to loss of motor control and severe mental deficiency. Symptoms usually appear between age 30-50 with death 12 years later.

Phenylketonuria or PKU Autosomal Recessive People with PKU cannot consume any product that contains phenylalanine until after they have reached physical maturity. Caused by a deficiency of an enzyme which is necessary for proper metabolism of the amino acid phenylalanine.

Color Blindness Recessive – Sex linked (on the x chromosome) 1/10 males have, 1/100 females have. Individuals are unable to distinguish shades of red-green.