Genetic Conditions: Hemophilia and Color Blindness

Study Notes

Genetic Conditions

Hemophilia: an inherited bleeding disorder where blood doesn't clot properly due to low levels of clotting factors VIII (8) or IX (9)
Hemophilia A: deficiency in factor VIII (8), most common type
Hemophilia B (Christmas Disease): deficiency in factor IX (9)
Hemophilia follows an X-linked inheritance pattern and is also known as the "royal disease" due to its presence in Queen Victoria of England

Color Blindness

Difficulty distinguishing between certain colors, more common in males than females
Occurs when certain cells in the retina of the eye, called cones, do not function properly
Red-green color vision defects: X-linked recessive inheritance, caused by mutations in the OPN1LW and OPN1MW genes on the X chromosome
Blue-yellow color vision defects: autosomal dominant pattern, caused by mutations in the OPN1SW gene on chromosome 7

Muscular Dystrophy and Klinefelter Syndrome

Duchenne Muscular Dystrophy: characterized by progressive muscle degeneration and weakness due to alterations of the dystrophin protein (chromosome 21), X-linked recessive inheritance pattern
Klinefelter Syndrome: affects the sex chromosome, caused by the presence of extra X chromosomes (47,XXY), aneuploidy trisomy condition

Turner Syndrome and Jensen Syndrome

Turner Syndrome: affects only females, absence of one copy of X chromosome (45,XO), monosomy, caused by non-disjunction
Jensen Syndrome: rare X-linked inherited disorder caused by mutations in the TIMM8A gene, involved in the import of proteins into the mitochondria

Pedigree Analysis and Autosomal Recessive Inheritance

Pedigree analysis: process of examining a pedigree to determine the pattern of inheritance for a trait
Autosomal recessive inheritance: two copies of the mutated gene, examples include cystic fibrosis, sickle cell disease, Tay-Sachs disease, and phenylketonuria

Cystic Fibrosis, Tay-Sachs Disease, and Phenylketonuria

Cystic Fibrosis: mutations in the CFTR gene, disrupting chloride ion transport across cell membranes, leading to buildup of thick, sticky mucus in lungs and digestive system
Tay-Sachs Disease: autosomal recessive genetic disorder, buildup of GM2 ganglioside in nerve cells of brain and spinal cord, causing progressive damage
Phenylketonuria (PKU): rare inherited metabolic disorder, inability to metabolize the amino acid phenylalanine, deficiency of the enzyme phenylalanine hydroxylase

Autosomal Dominant Inheritance

Autosomal dominant inheritance: 1 copy of the mutant allele is sufficient, examples include Marfan syndrome, Huntington’s disease, and achondroplasia

Description

This quiz covers genetic conditions, including hemophilia, an inherited bleeding disorder, and color blindness, a difficulty in perceiving colors. Learn about the different types of hemophilia and their causes.