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Klinefelter Syndrome

Results from at least 2 X chromosomes and 1 Y chromosome in each cell (47, XXY)

May have moderate degree of mental impairment

Male appearance, but develop gynecomastia

Usually sterile

Voice somewhat high-pitched

Body hair sparse

Testicles small

Treatment: Testosterone

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MENDELIAN SINGLE-GENE DISORDERSAUTOSOMAL DOMINANT DISORDERS:

MARFAN SYNDROME

Connective tissues mutations in fibrillin 1 gene on chromosome 15

Typically tall & slender with long, thin arms & legs, arachnodactyly (spider fingers)

President Abraham Lincoln?

Skeletal & joint deformities: pectus excavatum, abnormal curvature of spine

CV lesions most life-threatening: aortic rupture, valvular dysfunction

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HUNTINGTON DISEASE

Affects neurologic function abnormally large # of triplet repeats on chromosome 4 huntingt

protein aggregates in brain tissue

Mental deterioration

Involuntary movements of arms & legs (chorea, dance)

Onset age 40 yrs approximately

MENDELIAN SINGLE-GENE DISORDERSAUTOSOMAL RECESSIVE DISORDERS:

ALBINISM Lack of pigmentation of hair, skin, & eyes

Some forms have organ defects

High risk for sunburn & skin CA

Impaired vision

Photosensitivity

PHENYLKETONURIA (PKU)

Inability to metabolize the amino acid phenylalanine

Inborn error of metabolism

Buildup of dietary phenylalanine primarily affects nervous system

Overly irritable & tremorous

Slowly developing mental retardation

Musty odor

PKU testing @ birth

Treatment: low-phenylalanine diet

CYSTIC FIBROSIS

Defect in membrane transporter for chloride ions in epithelial cells

Abnormally thick secretions in glandular tissues, primarily lung bronchioles & pancreatic ducts,

resulting in progressive destruction

Mutation of gene on chromosome 7: deletion of 3 nucleotides that code for phenylalanine @

position 508

Clinical trials of gene therapy low success

Genetic screening for prevention & early mgmt

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MENDELIAN SINGLE-GENE DISORDERSSEX-LINKED (X-LINKED) DISORDERS:

HEMOPHILIA A

Deficiency of factor VIII (protein necessary for blood clotting)

Bleed easily & profusely from minor injuries

Almost always male

DUCHENNE MUSCULAR DYSTROPHY

G6PD DEFICIENCY

FRAGILE X SYNDROME

MULTIFACTORIAL (POLYGENIC) DISORDERS:

HIGH BLOOD PRESSURE

CANCER

DIABETES MELLITUS

CLEFT LIP

CONGENITAL HEART DEFECTS

PRENATAL DIAGNOSTIC STUDIES:

ULTRASOUND

To detect visible congenital anomalies: spina bifida, heart defects, malformations of face, head,body, limbs

AMNIOCENTESIS

To detect a-fetoprotein

16 weeks gestation

CHORIONIC VILLUS SAMPLING

8 weeks gestation

EMBRYOSCOPY

1st trimester

Gene or stem cell therapy