Defective gene from one or both parents1. Downs Syndrome2. Hemophilia3. Muscular Dystrophy4. Sickle Cell Anemia5. Cleft Palate6. Cystic Fibrosis7. Spina bifida
46 chromosomes carry thousands of genes. Contain all the characteristics a person will have.
Males have XY chromosomes Females have XX chromosomes Egg and Sperm cells have only 23 chromosomes All eggs are X, sperm can be X or Y Sperm 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 Geneeye coloring brown eyes grey, green, hazel, blue eyesvision 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* widows peak normal hairlinefacial features dimples no dimples unattached earlobes attached earlobes freckles no freckles broad lips thin lipsappendages 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 jointsother 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-linkedcharacteristic
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 Changs 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 Changs fame helped coin the phrase SiameseTwins, they were not the first pair of conjoined twins recorded inmedical annals as there were probably about 100 such pairsknown by the time of their 1811 births, a fact which helped theKing of Siam reverse an early death sentence on the brothers. Infact, conjoined twins were recorded as early as 945 in Armenia andthe first pair of successfully separated twins took place in 1689 byGerman physician G. König.The birth of two connected babies can be extremely traumaticand approximately 40-60% of these births are delivered stillbornwith 35% surviving just one day. The overall survival rate ofconjoined twins is somewhere between 5-25% and historicalrecords over the past 500 years detail about 600 surviving sets ofconjoined twins with more than 70% of those surviving pairsresulting in female twins.
Infertility: Problems of conception or implantation have occurred Fertility Analysis: What options does a couple have
a. Fertility Drugsb. Artificial Insemination – Sperm is injected into womans 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 transferd. Surrogate Mother: Carries fertilized egg through IVF for couple or may be artificially insemination by father’s sperme. 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