6.2 Human Genetic Disorders
Can you see if there’s an abnormality in
this picture?
What is genetic disorder?
• Def: Abnormal condition that a person inherits
through genes or chromosomes
• Ex.
–
–
–
–
Cystic Fibrosis
Sickle-Cell disease
Hemophilia
Down Syndrome
Causes of Genetic Disorders
• Some genetic disorders are caused by
changes in the DNA of genes. Other
disorders are caused by changes in the
overall structure or number of
chromosomes.
Genetic Disorders
• Cystic Fibrosis :
body produces abnormally
thick mucus in the lungs
and intestines, making it
hard for the person to
breathe. Caused by a
recessive allele on one
chromosome – result of a
mutation.
• Sickle-Cell disease: Red blood cells change
to a sickle shaped cell, which can clog blood
vessels. Codominant allele.
• Hemophilia : sex-linked disorder.
Person’s
blood will clot very slowly or not at all. Caused by
a recessive allele on the X chromosome.
• Down Syndrome – An extra copy of
chromosome 21. Some degree of mental
retardation.– Caused during meiosis:
chromosomes fail to separate properly.
Pedigrees
• An important tool that geneticists use to trace the
inheritance of traits in humans – a chart or “family
tree” that tracks which members of a family have
a particular trait.
Managing Genetic Disorders *
• Karyotype : picture of all the chromosomes in a
cell.
• Genetic Counseling: a couple that has a family
history of a genetic disorder may turn to a genetic
counselor for advice.
• Dealing with Genetic Disorders: Modifying an
affected person’s environment – ex. Through
medicine, diet, or education – can help manage
some disorders.
• Sickle cell : take folic acid(vitamin) to help make
red blood cells.