The other 10 percent of cases result from new mutations in one of the genes and occur in people with no history of the disorder in their family. Although one altered copy of a gene in each cell is sufficient to cause the disorder, an additional mutation in the second copy of the PKD1 or PKD2 gene may make cysts grow faster and increase the severity of the disease. The rate at which cysts enlarge and cause a loss of kidney function varies widely, and may be influenced by mutations in other, as yet unidentified, genes. Polycystic kidney disease also can be inherited in an autosomal recessive pattern. People with this form of the condition have two altered copies of the PKHD1 gene in each cell.
3. What are the symptoms? The clinical symptoms of cri du chat syndrome usually include a high-pitched cat-like cry, mental retardation, delayed development, distinctive facial features, small head size (microcephaly), widely-spaced eyes (hypertelorism), low birth weight and weak muscle tone (hypotonia) in infancy. The cat-like cry typically becomes less apparent with time. 4.
Children are usually diagnosed before six months of age, more often before three months of age. Symptoms may even start in the womb. (Hockenberry & Wilson, 2007, p. 1816)The most cardinal clinical manifestation of the disease is inactivity. Other symptoms are floppy limbs and trunk, feeble movements of the arms and legs, swallowing difficulties, poor sucking reflex, weakness, absent deep tendon reflexes, weak cry or cough, , flaccid or reduced muscle tone, the patient may tire easily, exhibit a failure to thrive, posses abnormal tongue movements, and the patient is unable to sit alone, roll over independently, or walk. Their chest may appear concave or Bell-shaped.
Tay-Sachs Disease and The Teaching Plan Tay-sachs disease is an inherited disease that is common among Ashkenazi-Jewish population. It occurs from a mutation in the HEXA gene also known as deficiency of the human chromosome 15 in DNA. This missing chromosome affects nerve cells in the brain. This disease is an autosomal recessive inheritance, “such diseases do not occur unless two genes for the disease are present, that is, a homozygous recessive pattern.” (Lippincott, 1999,p 150). There is a 25% risk of giving birth to an affected child with each pregnancy.
In Duchenne muscular dystrophy (DMD) lack of the protein dystrophin causes muscles to deteriorate and break down, leading to progressive difficulty with walking and general mobility. DMD is the most frequently occurring and one of the most rapidly progressive of the childhood neuromuscular disorders. It affects approximately 1 in 3500 live male births throughout the world. DMD affects only boys (with extremely rare exceptions). Around 10 to 20 percent of female carriers of the DMD gene mutation experience some of the symptoms of muscular dystrophy and these women are known as ‘manifesting carriers’.
DiGeorge Syndrome: Tbx1 gene and Cardiac Defects Tiffany Smith Genetics Review Paper Excelsior College Abstract DiGeorge syndrome is caused by the “micro” deletion of a section of chromosome 22 that results in the deletion of over 3 million DNA bases that can cause a wide variety of defects (McDonald-McGinn et al., 2001). The deletion of chromosome 22q11.2, also known as DiGeorge syndrome, occurs in about 1 in 4,000 births with over 80% exhibiting congenital heart defects. Gene analysis and genetic testing have identified genes responsible for the associated heart defects in patients with DiGeorge syndrome. Advancements in medical technology have improved surgical techniques to repair cardiac defects caused by the deletion of chromosome 22q11.2. There are not any cures for DiGeorge Syndrome but there are treatments available based on the degree of associated defects.
The gene contains a member of the fibroblast-growth-factor receptor (FGFR3) family, which is shown in articular chonfrocytes. A missense mutation in the fibroblast growth factor receptor, on chromosome 4p, in humans, causes achondroplasia. Symptoms of achondroplasia are 1- Disproportionately short arms and legs, 2- Short fingers, 3- A large head with a prominent forehead, 4: A mid-face, 5- Short stature, and 6: Decreased muscle tone. Some children have delayed motor milestones, bowing of lower legs, and frequent ear infections. Intelligence and life span is not affected while having achondroplasia.
Even though these characteristics were sometimes seen running in families, chromosomes appeared grossly normal. Dr John Opitz, a former student of Dr. Noonan, first began to call the condition "Noonan Syndrome" when he saw children who looked like those whom Dr. Noonan had described. Dr. Noonan later produced a paper entitled "Hypertelorism with Turner Phenotype", and in 1971 at the Symposium of Cardiovascular defects, the name 'Noonan Syndrome' became officially recognized. Noonan Syndrome Is a very common disease that has been tested a found out that 1 in 1,000 to 2,500 people have this disease.” Symptoms - * Delayed puberty * Down-slanting or wide-set eyes * Hearing loss (varies) * Low-set or abnormally shaped ears * Mild mental retardation (only in about 25% of cases) * Sagging eyelids (ptosis) * Short stature * Small penis * Undescended testicles * Unusual chest shape (usually a sunken chest called pectus excavatum) * Webbed and short-appearing neck Treatment - There is no specific treatment. Your doctor will suggest treatment to relieve or manage symptoms.
Task 1 Kleinfelters syndrome An error in cell division called nondisjunction which results in a reproductive cell with an abnormal number of chromosomes .Resulting in one of more x chromosomes. Resulting in a total of 47 chromosomes per cell. Downs syndrome An error during anaphase causes problems like trisomy 21 when there is 3 chromosomes for the chromosomes pair 21. Name two conditions /disease caused by gene mutation. Haemophilia Albinism Task 2 (B) Sickle cell anaemia Anaemia Anaemia is a lack of blood cells which is a common symptom of sickle cell anaemia.
It is the most common of the embryonal tumors which arise from emybryonal or immature cells at the earliest stageof their development(Medulloblastoma). The symptoms that are most common for this tumor are behavioral changes, changes in appetite, increased pressure of the brain , headache,neausea,vomiting,and drowiness, along with problems with coordination, and unusual eye movements(Medulloblastomas).This tumor is rare it makes up less than two percent of all primary brain tumors and eighteen percent in child brain tumors. more than seventy percent of children under ten are diagnosed with pediatric medulloblastomas. Very few occur in children up to the age of one(medulloblastoma). Scientists believe they may have found changes withnin the genes and chromosomes that may play a role in the development of this