Chapter 1 INTRODUCTION A. BACKGROUND OF THE STUDY Chromosomal abnormalities which frequently cause physical and cognitive abnormalities for a child throughout life are usually evident at birth. Nondisjunction, deletion translocation, mosaicism, and isochrosome abnormalities are some of the various forms of chromosomal abnormalities (Hatfield, 2008). Nondisjunction is the most common type of chromosomal abnormalities which occur through uneven chromosomal division. During cell division of the cells reproduction, the 46 chromosomes should be divided into half having 23 chromosomes in each new cell.
Similar disorders include Nager Sydrome and Miller Syndrome. Mutations in the TFOC1 gene are most commonly the cause for Treacher Collins. Mutations in this gene have been proven to affect the production of rRNA. Decreased production of rRNA causes the death of cells affecting the development of facial structure, causing the abnormalities of the face seen in Treacher Collins. Treacher Collins causes downward sloping eyes (these can lead to vision issues), ears may be undersized or completely absent, no ear canal, middle ear bones can be missing affecting hearing, missing cheek bones, underdeveloped jaw, cleft pallet can occur, these facial issues can lead to problems with speech, swallowing, and sometimes breathing.
(13) Charcot Marie Tooth Disease is caused by a mutation within one of our genes and it can happen to any ethnic group and affects 1 out of every 3, 300 people worldwide. (3) Mutations within our genes are inherited and each of us carries two copies of each gene, one from each parent. There are many forms of Charcot Marie Tooth (CMT) disease; however, the one focused on for this research paper is CMT1A. (3, 6, 9) There are three main types of CMT1, which are all caused by abnormalities in the myelin sheath found on the neurons of the peripheral nerves. CMT1A is an autosomal dominant disease.
Mutation is the main cause of cystic fibrosis. Mutation that happens on an autosomal recessive allele on chromosome 7 which causes cystic fibrosis was identified in the 1990’s. A protein named cystic fibrosis transmembrane regulator (CFTR) was affected by the mutation, known as trinucleotide deletion of TTT, in the gene which is positioned on chromosome 7. This mutation is known as Delta F508 because it causes the deletion of amino acid phenylalanine (F), numbered as 508 in the protein. This deletion causes the regulatory mechanism of movement of chloride across the cell membrane becomes obstructed and this result in irregular salt loss and mucus secretions in the patient’s body
----------------------- BY: KYLE NAVALTA What is it? Alagille syndrome is a genetic disease and an autosomal dominant disorder. Alagille syndrome is associated with abnormalities with the liver, heart, and several different parts of the human body. (1,2,4) ALAGILLE SYNDROME (Autosomal) [pic] Prevalence An estimated popularity of Alagille syndrome is 1 in 70,000 newborns. (4) Stages & Symptoms Alagille syndrome may accommodate symptoms like Liver: Jaundice which is the yellowish staining in the skin and whites of the eyes.
Scientist and doctors believe that there are more than one thousand ways the cf gene can mutate and the various mutations could cause the different symptoms. The cf gene that has the scientific name ABCC7 makes a protein called CFTR (cystic fibrosis transmembrane conductance regulator). The CFTR protein is found in cells called epithelial cells which form a lining inside many organs. Sometimes cystic fibrosis is diagnosed before a baby is born, but many infants are diagnosed shortly after birth. Most infants with cystic fibrosis are born with Meconium Ileus.
One missing piece, called TERT (telomerase reverse transcriptase) is involved in control of cell growth, and may play a role in how some of the features of this syndrome develop. It is believed to occur during the development of the egg or sperm. A few cases result from one parent carrying a rearrangement of the fifth chromosome. The symptoms vary, but the most common is a high pitched crying that sounds like a cat when the baby is born. There could be partial webbing of the finger and toes and the eyes could be slanted or wide setted.
Blocked blood flow can cause damage to organs, pain attacks, or death. Sickle cell is most common in African Americans and Hispanics of Caribbean ancestry. 1 in every 400 African Americans has sickle cell (Borgna-Pignatti 104). There are different types of sickle cell: Sickle cell Anemia and Sickle Cell Trait. Sickle cell Anemia is a genetic disorder also inherited by both parents.
In 1959, Down Syndrome was described as a trisomy 21 by Dr. Jerome Lejeune. Down Syndrome can either be identified in a baby at birth or in a prenatal screening. The Center for Disease Control estimates that one in every 691 babies in America has down syndrome, making it the most common genetic disorder in America. Around 400,000 Americans and around 6,000 babies have Down Syndrome. There are three types of Down Syndrome.
Congenital malformation: A physical defect present in a baby at birth, irrespective of whether the defect is caused by a genetic factor or by prenatal events that are not genetic. In a malformation, the development of a structure is arrested, delayed, or misdirected early in embryonic life and the effect is permanent. Congenital malformations can involve many different organs including the brain, heart, lungs, liver, bones, and intestinal tract. These defects can occur for many reasons including inherited (genetic) conditions, toxic exposure of the fetus (for example, to alcohol), birth injury and, in many cases, for unknown reasons. All parents are at risk of having a baby with a birth defect, regardless of age, race, income or residence.