Huntington’s is caused by a faulty DOMINANT GENE You only need one copy of the gene from the affected parent. Each child has a 50% chance of inheriting the gene.

Huntington’s Disease Causes the death of nerve cells in the brain. SYMPTOMS: Appear yrs Forgetfulness Clumsy Jerky movements Personality changes Loss of movement Struggle to swallow Death 20 years after symptoms appear.

FAULTY RECESSIVE GENES Cystic Fibrosis PKU Albinism

PKU (Phenylketonuria) Caused by a pair of faulty recessive genes. Body cannot make a digestive enzyme to break down an amino acid (found in proteins). Leads to a toxic substance building up in the blood. This toxic substance damages the brain affecting brain development- mental retardation (low intelligence)

The PKU heel prick test is a form of screening carried out on newborns to check for PKU.

PKU (Phenylketonuria) Management consists of a special diet to reduce PKU levels. No breast milk. No chicken, nuts, fish, cheese or beans.

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Albinism Albinism affects the production of melanin, which is the pigment that colours the hair, skin and eyes. People with albinism usually have: Sensitivity to light, known medically as photophobia. They may feel dazzled by bright light. Problems with eyesight, such as short- sightedness. They may benefit from glasses, but their vision is usually still impaired even with glasses. Involuntary movements of the eye, known as nystagmus.

GENETIC DISEASE GENETIC CAUSE Down’s SyndromeExtra copy of chromosome 21 Huntington’s Disease Faulty Dominant gene Cystic FibrosisPair of faulty Recessive genes PKUPair of faulty Recessive genes AlbinismPair of faulty Recessive genes HaemophiliaFaulty gene on X chromosome Red-green Colour blindness Faulty gene on X chromosome