Genetic Disorders during

Prenatal Development

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Prenatal Development

Prenatal or antenatal development is the process in which a human

embryo or fetus gestates during pregnancy, from fertilization until birth.

Genetic disorders during prenatal development:

Genetic disorders are physical defects or illnesses that are caused by

problems in body's genetic code.

Genetic disorders are responsible for one third of all birth defects.

Genetic disorders may be grouped within three groups:

Chromosome number abnormalities

Chromosome structure abnormalities

Gene mutations

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Chromosome number abnormalities: Monosomy

45 XO Turner’s syndrome

Trisomy

Klinefelter syndrome

Edward’s syndrome

Down’s syndrome

Tetrasomy

Pentasomy

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Chromosome Structure Abnormalities: Mosaicism

Translocation

Chromosome deletion

Microdeletion

Prader-villi Syndrome

Prader-villi syndrome Translocation Microdeletion

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Gene Mutation

Autosomal dominant

inheritance:

Achondroplasia

Ectrodactly

Polydactyly

Osteogenesis Imperfecta

Osteogenesis imperfecta Achondroplasia

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Autosomal recessive inheritance

Cystic fibrosis

Childhood spinal muscular atrophy

Tay-sachs disease

Phenylketonuria (PKU)

Tay-sachs disease

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X-linked inheritance

Rett Syndrome-

Hemophilia

Duchenne’s muscular

dystrophy

Fragile X Syndrome

Other genetic disorders:

Sickle cell anemia

Thalessemia

spinabifida

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Causes

Teratogens

Maternal diseases:

• Rubella- blindness, deafness, brain damage

• Chicken pox and mumps- birth defects, miscarriage

• Syphilis and gonorrhea- transmitted to child

• AIDS- small mishappen face, protruding lips, brain deterioration

• Herpes Virus- deafness, brain swelling, mental retardation

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Causes

Maternal drug use:

aspirin can lead to bleeding

thalidomide caused missing limbs

marijuana restricts oxygen to the fetus

methamphetamine is linked to low birth weight and neurological impairment.

cocaine restricts blood flow and oxygen.

Both alcohol and cigarettes can disrupt the development of the fetus,

FETAL ALCOHOL SYNDROME (FAS) is a disorder caused by the pregnant mother consuming substantial quantities of alcohol during pregnancy potentially resulting in mental retardation, delayed growth, and facial deformities.

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Prevention

Vaccination

Folic acid dosage

Avoid unnecessary medicines

don't smoke

don't drink alcohol

avoid all illicit drugs

get exercise and plenty of rest

get early and regular prenatal care

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Diagnosis

Genetic counseling

Prenatal testing

Ultrasound: 6-10, 16-20 weeks

Amniocentesis: 16-20 weeks

Chorionic villus sampling:

10-12 weeks

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