LESSON 2 - SEX LINKED TRAITS AND DISORDERS

genetic diseases

• when our genes dictate the path of our health

chromosomal, single-gene, complex disorder

three types of genetic disorder

chromosomal disorder

• where chromosomes are missing or changed

• chromosomes are the structures that hold our genes

• down syndrome is an example of this

single-gene disorder

• where a mutation affects one gene

• sickle cell anemia is an example

complex disorder

• where there are mutation in two or more genes

• often your lifestyle and environment also play a role

• colon cancer is an example

sex linkage

• refers to the inheritance pattern of certain traits or genes that are located on the sex chromosomes, typically the X chromosome in mammals

sex link trait

• trait determined by an allele or gene on the sex chromosome

x linked trait

• genes on the x chromosome

• in males, who only have one X chromosome, any recessive allele on that chromosome will show up, even if its recessive because there’s no matching allele on the Y chromosome to hide its effects

x-linked dominant

• fragile x syndrome

x-linked recessive

• hemophilia

• fabry disease

y-linked traits

• these are traits or genes located on the Y chromosome

• they are inherited exclusively from father to son because only male have Y chromosome

sex-limited traits

• these are traits controlled by genes on autosomes but are only expressed in one sex

• one example is milk production in mammals is a sex-limited trait expressed only in females

sex-influenced traits

• these are traits that are influenced by the sex of the individual

• these traits are not located on sex chromosomes but are expressed differently in males and females due to hormonal differences

• male pattern baldness is an example

autosomal traits

• autosomal dominant traits pass from one parent onto their child

• recessive traits pass from both parents onto their child

• refers to the 22 numbered chromosomes as opposed to the sex chromosome

huntington disease

• is a brain disorder in which brain cells or neurons in certain areas of your brain start to break down

• HD is caused by mutation in a gene located on chromosome 4

• As the neurons degenerate, the disease can lead to emotional disturbances, loss of intellectual abilities , and uncontrolled movement

marfan syndrome

• a congenital condition, meaning a person has it from birth

• is an autosomal dominant disorder that has been linked to the FBN1 gene on chromosome 15

• physical signs sometimes present in infancy but more often show up later in childhood or adolescence

• both the cardiovascular and skeletal systems are affected by this condition

cystic fibrosis

• an inherited disease characterized by an abnormality in the glands that produce sweat and mucus

• caused by the mutation of a single gene on the long arm of chromosome 7 that codes for the CF transmembrane regulator

• affects various organs systems in children and young adults, including the respiratory system, digestive system and reproductive system

sickle cell anemia

• the hemoglobin is abnormal which causes the red blood cells to become hard and sticky and look like a C shaped farm tool call sickle

• it is caused by a mutation in the hemoglobin-beta gene found on chromosome 11

• the sickle cells die early which causes a constant shortage of red blood cells

trisomy

• a chromosomal condition characterized by an additional chromosome

• a person with a trisomy has 47 chromosomes instead of 46

• down syndrome, edward syndrome, and patau syndrome are the most common for of this disorder

klinefelter syndrome

• most men are born with a pair of XY chromosomes while most female are born with XX chromosomes

• this disorder occurs when a male is born with an extra X chromosome

• thus a male with this disorder has XXY instead of the usual XY pair