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Inflammatory bowel disease UV-induced skin (Crohn disease) damage, vulnerability to Night blindness, congenital stationary, type 1 Night blindness, congenital stationary, type 2 Hypertrichosis, congenital generalized Breast cancer, early onset Ovarian cancer Combined factor V and VIIl deficiency Sex-determining region Y (testis determining factor) Gonadal dysgenesis, XY type Azoospermia factors Louisiana State University Health Sciences Center, Shreveport Gene Expression Overview of Control...

Oooc oc

Peroxisomes result in Zellweger syndrome, which is characterized by structural and developmental abnormalities and which is generally fatal in infancy. Defects in individual peroxisomal enzymes are also encountered, including Refsum disease, which results in the buildup of a branched-chain fatty acid (phytanic acid) and progressive problems in the nervous system. A defect in the enzyme alanine-glyoxylate transaminase causes an increase in the production of oxalic acid, an insoluble chemical...

Human Mutation Rates

The appearance of rare dominant genetic diseases, such as retinoblastoma, have been used to estimate the mutation rate in the human population. Retinoblastoma is a childhood cancer of the eye and was a lethal condition until recently. Hence almost every case represented a new mutation (because individuals with the condition did not survive to reproduce and pass the genetic propensity for the disease along to their offspring), and the mutation rate could thus be readily estimated. Modern methods...

Approaches to Treatment

Treatment approaches for metabolic disorders include (a) modifying the diet to limit the amount of a precursor that is not metabolized properly (b) using cofactors or vitamins to enhance the residual activity of a defective enzyme system (c) using detoxifying agents to provide alternative pathways for the removal of toxic intermediates (d) enzyme replacement, to provide functional enzymes exogenously (from the outside) (e) organ transplantation, which in principle allows for endogenous...

Light and Radiation

Radiation refers to two different phenomena light and high-energy particles. Visible light represents a small slice of the electromagnetic spectrum, which includes long-wavelength (low-energy) radio waves and short-wavelength (high-energy) ultraviolet waves, plus X rays and gamma rays. These high-energy forms can directly disrupt DNA by breaking its chemical bonds. In severe cases, this can break apart chromosomes, causing chromosome aberrations. More often, they create mutagenic free radicals...

Viewing Chromosomes

Biologists first tried to visualize the chromosomes in a human cell in the late nineteenth century, with estimates of the total number ranging from 30 to 80. As methods to untangle and stain chromosomes improved, the count narrowed to 46 or 48, and by 1956 was confirmed as 46, or 23 pairs. By 1959, the first chromosomal abnormalities were identified using size and crude staining patterns to distinguish the chromosomes. In the 1970s, vastly cytogeneticists scien- improved staining techniques...

Schizophrenia and Bipolar Disorder

Schizophrenia is a disorder characterized by psychotic symptoms such as hallucinations, delusions, and disordered thinking, as well as deficits in emotional and social behavior. Numerous family, twin, and adoption studies have provided substantial evidence for genetic factors in the etiology of this dis- etiology causation of disease, or the study of causation order. Nongenetic factors also appear to play an important role. The risk for relatives of an individual with schizophrenia is 6.5...