Biology(5) Diseases and Abnormalities Caused by Mutation

Genetic Disorders

According to the National Human Genome Institute, almost all disease has some sort of genetic factor. These disorders can be caused by a mutation in a single gene, multiple gene mutations, combined gene mutation, and environmental factors, or by chromosome mutation or damage.

Sickle Cell Anemia

* a genetic disease common among those who are from **Africa.**
* This genetic disease is the __result of a point mutation where there is__ __**a change in just one nucleotide**__ in the gene for hemoglobin. The mutation causes the hemoglobin in red blood cells to transform to a sickle shape when de-oxygenated.

Cystic Fibrosis

* a progressive, genetic disease that affects the secretory glands, including the **mucus** and **sweat glands.**
* causes persistent lung infections and __limits the ability to breathe over time.__

Tay-Sachs Disease

* a rare inherited disorder that **causes progressive damage to the nervous system** and most commonly affects **infants.**
* It is mainly caused by the

absence of a vital enzyme called __**hexosaminidase-A (Hex-A)**__
* only occurs w__hen both parents carry a Tay-Sachs gene__ and each parent transmits the defective gene to their child.
* located on chromosome 15

Hemophilia

* an inherited bleeding disorder that causes a**bnormal or exaggerated bleeding and poor blood clotting.**
* 1/3 of cases are caused by a __spontaneous mutation__
* The most common type of hemophilia is __**hemophilia A**__. Common symptoms include excessive bleeding and easy bruising.

Down Syndrome

* most common chromosomal disorder.
* have 47 chromosomes in their cells instead of 46, and suffer from mild to moderate disabilities.
* three main types of Down syndrome: *trisomy 21, mosaicism,* and *translocation*

Trisonomy 21

* **most common form of Down syndrome**, accounting for about __**95%**__ of cases.
* caused by uneven separation of chromosome 21 during the creation of sex cells

Mosaic

* **much less common**__**,**__ accounting for about 1% of cases
* the uneven separation of chromosome 21 happens __**shortly after an egg has been fertilized.**__
* Because only some cells have the extra chromosome, mosaic Down syndrome __**may have less prominent symptoms**__ than trisomy 21.

Translocation

* when a portion of chromosome 21 __breaks off during the replication process, and then attaches to another chromosome.__
* So rather than getting a full extra chromosome, translocation results in cells with the typical 46 chromosome, **plus a little extra chromosome 21.**

Physical features of Down Syndrome

1. A flattened face, especially the bridge of the nose
2. Almond-shaped eyes that slant up.
3. A short neck
4. Small ears
5. A tongue that tends to stick out of the mouth
6. Tiny white spots on the iris (colored part) of the eye Small hands and feet
7. A single line across the palm of the hand (palmar crease)
8. Small pinky fingers that sometimes curve toward the thumb
9. Poor muscle tone or loose joints
10. Shorter in height as children and adults

Klinefelter Syndrome

* __**known as XXY condition**__ is a chromosomal condition that affects male physical and cognitive development.
* The most common symptom is __**infertility.**__
* is a chromosomal condition in boys and men that can affect *physical* and *intellectual development.*

Prader Willi Syndrome

* complex genetic disorder that affects *growth, metabolism, appetite, cognitive function, behavioral problems, low levels of sex hormones* and *a constant feeling of hunger.*
* It is caused by the **loss of genes** in a specific region of __**chromosome 15**__

Turner Syndrome

* a rare chromosomal ailment that **impacts girls.**
* associated with the x chromosome that alters development in women, __even though it isn't normally inherited in families.__
* Infertility, most consistent functions of TS are brief stature and lack of ovarian development

Edward’s Syndrome

* __**also known as Trisomy 18 (T18) or Trisomy E**__
* The majority of people with the syndrome die during the fetal stage;
* named after **John H. Edwards**, who first described the syndrome in 1960.
* a broad spectrum of abnormalities which consist of __greater than one-hundred and thirty discrete defects involving the brain, heart, craniofacial structures, kidneys and stomach.__

Cri Du Chat

* a genetic condition __present from birth__ that affects growth and development.
* Infants with this condition often have a **high-pitched cat- like cry, small head size, and a characteristic facial appearance.**
* __**due to a missing piece (deletion)**__ of a specific part of chromosome 5 known as the 'p' arm.

Jacobseb Syndrome

* a condition __**caused by a loss of genetic material**__ from chromosome 11.
* is also **known as 11q terminal deletion disorder.**
* Affected individuals often have a large head size (macrocephaly) and a skull abnormality calledtrigonocephaly, which gives the forehead a pointed appearance.

Klinefelter’s Syndrome

* genetic condition in **which a boy is born with an extra X chromosome.**
* Men with Klinefelter usually don’t know they have it until they run into problems trying to have a child. __**There’s no cure, but it can be treated.**__

Karyotyping

a laboratory procedure that allows your doctor to examine your set of chromosomes. “

“Karyotype”

also refers to the actual collection of chromosomes being examined.