Heredity

The passing on of certain inherited characteristics from one generation to another.

Hair

Eyes

Height

Intelligence

Talents

Dimples

Defective gene from one or both parents

1. Downs Syndrome

2. Hemophilia

3. Muscular Dystrophy

4. Sickle Cell Anemia

5. Cleft Palate

6. Cystic Fibrosis

7. Spina bifida

46 chromosomes carry thousands of genes.

Contain all the characteristics a person will have.

Males have XY chromosomesFemales have XX chromosomesEgg and Sperm cells have only 23

chromosomesAll eggs are X, sperm can be X or YSperm cell from father determines sex

of baby

Chromosome: Threadlike particles in nucleus of cell which carries hereditary factors.

Genes: Part of the chromosome that determines all inherited characteristics

Dominant: Stronger gene that determines appearance of a trait.

Recessive: Weaker gene; will not appear when paired with a dominant gene

Dominant Gene Recessive Gene

eye coloring brown eyes grey, green, hazel, blue eyes

vision farsightedness normal vision

normal vision nearsightedness

normal vision night blindness

normal vision color blindness*

hair dark hair blonde, light, red hair

non-red hair red hair

curly hair straight hair

full head of hair baldness*

widow's peak normal hairline

facial features dimples no dimples

unattached earlobes attached earlobes

freckles no freckles

broad lips thin lips

appendages extra digits normal number

fused digits normal digits

short digits normal digits

fingers lack 1 joint normal joints

limb dwarfing normal proportion

clubbed thumb normal thumb

double-jointedness normal joints

other immunity to poison ivy susceptibility to poison ivy

normal pigmented skin albinism

normal blood clotting hemophilia*

normal hearing congenital deafness

normal hearing and speaking deaf mutism

normal- no PKU phenylketonuria (PKU)

* sex-linked

characteristic

A. Identical twins: 1 egg + 1 sperm -- splits into two children, must be the same sex.

B. Fraternal Twins: 2 eggs + 2 sperm –both fertilized; can be same sex or one of each.

C. Siamese Twins: Conjoined twins – 1 egg + 1 sperm split, however the split does not completely occur.

Identical Twins: One fertilized egg splits in half, each half develops into

a separate embryo. Happens soon after fertilization

Offspring share DNA, they are the same sex

ONE EGG, ONE SPERM, ONE PLACENTA

Fraternal Twins: Two eggs are released at same time, each fertilized by

different sperm. No more alike genetically than any siblings

TWO EGGS, TWO SPERM, TWO PLACENTAS

ONE EGG, ONE SPERM EGG STARTS TO SPLIT AS IN IDENTICAL TWINS, BUT

DOESN’T COMPLETE THE SPLIT. EMBYROS WILL DEVELOP ATTACHED can be extremely traumatic approximately 40-60% of these births are delivered

stillborn with 35% surviving just one day. overall survival rate between 5-25% historical records over the past 500 years detail

about 600 surviving sets of conjoined twins with more than 70% of those surviving pairs resulting in female twins.

There is an extremely rare form of identical twins that occurs perhaps in one out of every 75,000 to 100,000 births or 1 in 200 deliveries of identical twins, that of conjoined twins. Conjoined twins originate from a single fertilized egg so they are always identical and same-sex twins. The developing embryo starts to split into identical twins within the first two weeks after conception but then stops before completion, leaving a partially separated egg which continues to mature into a conjoined fetus.

The most famous set of conjoined twins were Chang and Eng, the men who originated the term "Siamese Twins". Eng and Chang were born in Siam (modern day Thailand) on May 11, 1811 to a Chinese father and half-Chinese, half-Malay mother. Thanks to their heritage, while growing up in Siam the boys were known as "The Chinese Twins". Despite the fact that their birth was initially believed to be an omen of the end of the world, they brought celebrity to their small village. Their mother refused to allow doctors to attempt to separate the boys, fearing that to do so would result in the death of one or both. Instead she taught them to stretch the tissue that joined them so that they could stand side-by-side rather than always face-to-face.

Chang and Eng began to date Adelaide and Sarah Ann Yates, two of nine daughters of local farmer and part-time clergyman, David Yates. The townspeople disapproved, so Chang and Eng scheduled a separation surgery in Philadelphia. Their fiancées found out and quickly stopped the proceeding, and in April, 1843, Chang was married to Adelaide and Eng to Sarah Ann in a double wedding.

During the course of their marriages, Eng fathered six boys and five girls; Chang seven girls and three boys. All were normal except for a son and daughter of Chang's who were deaf mutes.

In January, 1874, Chang Bunker died after a severe case of bronchitis, possibly from a cerebral clot. Eng died shortly thereafter.

After their deaths it was determined they could have been successfully separated, a medical option that was never offered to Eng and Chang during their lives.

Although Eng and Chang's fame helped coin the phrase 'Siamese Twins', they were not the first pair of conjoined twins recorded in medical annals as there were probably about 100 such pairs known by the time of their 1811 births, a fact which helped the King of Siam reverse an early death sentence on the brothers. In fact, conjoined twins were recorded as early as 945 in Armenia and the first pair of successfully separated twins took place in 1689 by German physician G. König.

The birth of two connected babies can be extremely traumatic and approximately 40-60% of these births are delivered stillborn with 35% surviving just one day. The overall survival rate of conjoined twins is somewhere between 5-25% and historical records over the past 500 years detail about 600 surviving sets of conjoined twins with more than 70% of those surviving pairs resulting in female twins.

Infertility: Problems of conception or implantation have occurred

Fertility Analysis: What options does a couple have

a. Fertility Drugs

b. Artificial Insemination – Sperm is injected into woman's uterus.

c. IVF (Invitro-Fertilization) – Sperm and egg are fertilized outside of body and then placed in the uterus – Test tube baby – very expensive with only a 80-90% chance of pregnancy. Variation: Ovum transfer

d. Surrogate Mother: Carries fertilized egg through IVF for couple or may be artificially insemination by father’s sperm

e. Adoption

An abnormality that affects the structure or function of the body.

Hereditary & Environmental

Any pregnancy that ends due to natural causes before the embryo/fetus could possibly survive on its own.

20% of pregnancies end in miscarriage

After 20 weeks, known as a stillbirth

Anything affecting the fetus by what the mother has done while pregnant; poor nutrition, alcohol, drugs, x-rays etc.

Downs Syndrome: 21st chromosome pair has 3 chromosomes instead of usual 2

Mother and baby have different blood types;

Example: Mother RH -, Father RH +, = Baby RH+

Mother will have an RH different from her own after labor and delivery and her body will begin to make antibodies to fight of this “intruder”

Next baby is rejected by mothers immune system.

Informs parents in advance the odds that their children will have a certain disease.

Parents suspect a problem from:

1. Medical/Family History

2. Physical Exam

3. Lab Tests

Amniocentesis: Needle inserted through belly button withdraws amniotic fluid; Recommended for women over 35.

Ultra Sound – Sound waves make an image to insure fetus is developing normally.

Chorionic Villi Sampling: Catheter goes through vagina into uterus for sample of tissue from membrane encasing fetus; Can find out results much sooner that amniocentesis.

Alcohol – FAS, Women should not have any amount

Over the Counter Medications: Aspirin, Ibuprofen etc. May cause problems for baby

Caffeine: Coffee, tea, sodas, chocolate;

Tobacco: Premature & Low birth weight

Illegal Drugs: Serious addictions and brain damage

X-rays: Radiation; make sure to tell Doctor or Tech.

Rubella or German Measles: Vaccine now

STD’s : Birth defects or blindness etc.

Other Infections: Should always discuss with doctor.

Addiction passed on to fetus

Prematurity and low birth weight

Withdrawal – painful and may even cause death

Birth defects

Learning Disorders