Human Genetic Disorders Their symptoms…

Albinism inherit genes that do not make the proper amounts of pigment !

Albinism Homozygous recessive

Cystic Fibrosis (CF) homozygous recessive trait on (autosomes) *

Sickle Cell Anemia (substitution of adenine for thymine) homozygous recessive *

Sickle Cell Anemia

Polydactyly (autosomal) homozygous recessive *

Polydactyly

Webbing of Fingers (autosomal) !

Webbing of Toes (autosomal) *

Klinefelters Syndrome XXY Nondisjunction Tallness with extra long arms and legs Abnormal body proportions (long legs, short trunk) Enlarged breasts Lack of facial and body hair Small firm testes Small penis Lack of ability to produce sperm Diminished sex drive Sexual dysfunction Learning disabilities Personality impairment

Klinefelters syndrome presenting “leg ulcers” 1/50 –1/1000 are born With KS Extra X chr. #47 Due to anaphase lag (fails to separate) Chronic venus Insufficiencies Obesity Reduced testosterone Therapy (cause)

Turners syndrome X Nondisjunction Turner syndrome is a birth defect caused by the absence of an X chromosome in some or all cells of a female, which inhibits sexual development and usually causes infertility. MONOSOMY – zygote with 45 chromosomes

Continue… In Turner syndrome, an error occurring very early in development results in an abnormal number and arrangement of chromosomes. Most commonly, an individual with Turner syndrome will be born with 45 chromosomes in each cell rather than 46. The missing chromosome is an X chromosome. The affected person is always female

Mosaics… More than half of all girls with Turner syndrome are mosaics, which means that the mutation occurs in some but not all cells of their body. Therefore, Turner syndrome can vary in severity. The fewer the affected cells, the milder the disease 1 / 2,500 female births have turners syndrome

Symptoms of Turner Syndrome short stature webbed skin of the neck abnormal eye features (drooping eyelids) abnormal bone development, such as a "shield-shaped," broad flat chest absent or retarded development of secondary sexual characteristics that normally appear at puberty, including sparse pubic hair and small breasts coarctation (narrowing) of the aorta bicuspid aortic valve infertility dry eyes absence of menstruation

Webbed Neck

Webbed Neck

Turner’s syndrome

Mom and her daughter with Turner’s Syndrome *

Down’s Syndrome nondisjunction *

Children with Down’s syndrome Trisomy 21 *

Who gets dwarfism and bone dysplasias? Bone dysplasias and dwarfism are rare. The most common type of dwarfism (achondroplasia) occurs in one in 15,000 children. A defective gene that stops bone from growing in the usual way causes most bone dysplasias. Sometimes this gene is passed on from a parent to a child (genetic). Much more often, though, the condition arises from a new change in the gene (spontaneous genetic mutation), and the baby is the first in her family to be affected.

Achondroplasia Autosomal dominant

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Thumbelina has dwarfism *

Huntington’s Disease (HD) (autosomal dominant allele) *

Symptoms of HD Mild forgetfulness and irritability Appears between 30-40 yrs. Old Loss of muscle control Uncontrollable physical spasms Severe mental illness Eventually death

Phenylketonura (PKU) Autosomal homozygous dominant Lacking amino acid phenylalanine Loss of motor skills, mental dibilitation Treatment: diet change, restricted diet

Tay Sach Autosomal recessive Normal 1st 6 months Deterioration of nerve cells Treatment: enzyme replacement therapy

Cri DU Chat Syndrome Missing piece of chromosome #5 Most are not inheritted High pitch cry that sounds like a cat Intellectual disability and delayed development Small head size Treatment: behavior modified programs

Marfan’s Syndrome Dominant Defective connective tissue, tall, long limbs, thin fingers (heart valves and aorta) Treatment: as problems arise

Muscular Dystrophy Genetic or malnurishment (prenatal) Progressive skeletal weakness

Hemophilia X linked disorder Lack of blood clotting factor (platelets) Treatment: transfusions platelets

Vocab… Pleiotropy = one gene for many characteristics. Ex: sickle cell Polygenic = many genes for one characteristic. Ex: skin color, height