Genetics and Prenatal Development 2 Genetics and Prenatal Development

Genetic Basics Building Blocks of Life Chromosomes DNA Genes Genomes There are about 23,000 different genes which would encompass the human Genome. Highlight the definition of each term ‘

Genetic Basics Expression of Traits Genotype-The totality of an individual’s genes Phenotype-Actual Characteristics This is what is seen or observed and can include a wide range of things Website shows impact of environment on physical appearance on genetically identical twins

Website shows impact of environment on physical appearance on genetically identical twins Studies of identical twins illustrate how different factors like smoking, sun exposure, depression and weight gain can influence aging. Age 52. The twin on the left smokes and has a history of more sun exposure, resulting in an older appearance than her twin of the same age. Photo: Dr. Bahman Guyuron

Genetic Basics Expression of Traits Dominant Genes-Expressed characteristics Recessive Genes-Not expressed, although it is a part of the genotype (genetic background) Allele-Alternate form of a gene Dominant-Recessive Inheritance This can be used to explain curly and straight hair for SINGLE Dominant Genes

Table 2.1 Traits With Single-Gene Dominant–Recessive Inheritance This can be used to explain curly and straight hair for SINGLE Dominant Genes Table 2.1 Traits With Single-Gene Dominant–Recessive Inheritance

Genetic Basics Expression of Traits Incomplete Dominance Phenotype influenced primarily but not exclusively by the dominant gene Polygenic Inheritance Interaction of multiple genes Incomplete dominance can be seen with sickle cell anemia as an example. One gene could be recessive for disorder and the other gene is dominant which makes a person a carrier of sickle cell without having sickle cell. This makes the individual more resistant to malaria.

Genetic Basics The Sex Chromosomes The 23rd chromosomes pair determine male or female Males more vulnerable to X-linked recessive disorders

Genetic Basics Genes and Environment Behavior Genetics Estimating influence of genes and environment on development Utilize twins to understand importance of genetics and tease out environment effects Since identical twins share identical genes and fraternal twins only about 40-60% by comparing similarities and differences one can get an indication of the role of genes on certain traits. Studying adopted children can also be beneficial

Genetic Basics Genes and Environment Heritability An estimate of the extent to which genes are responsible for differences among persons within a specific population Concordance Rates Percentage that indicates degree of similarity in phenotype among pairs of family members Heritability ranges form 0-1 and provides information about some degree of impact of genes and environment. Concordance rates can indicate some degree of genetic contribution of a condition.

The Human Experience Conception and Prenatal Development

Sperm and Egg Formation Cell Division Define the major terms Gametes which are reproductive cells (sperm and ovum). Use slide and figure to visually demonstrate meiosis as a variation of mitosis. Mitosis is normal cell duplication and division with 46 chromosomes. Meiosis is duplication and division with 46 chromosomes but in the process a division occurs to allow only 23 chromosomes (ovum and sperm cells)

The Beginning of Life Conception For conception to occur there must be a released ovum and a sperm. Ovulation releases the ovum, and if sperm available, fertilization can occur. There is only about a 24 hour window for fertilization to take place after ovum enters the fallopian tube. Sperm can last 2-5 days in a woman’s body to try to fertilize the ovum. In some cases instead of one ova being released, two are released which, if fertilized, can lead to fraternal or dizygotic twins. (Mention ethnic variation here as well)

The Germinal Period First 2 Weeks of Life During the travel from the fallopian tube to the uterus cell division is taking place Blastocyst Trophoblast Embryonic disk Describe cell division as well as the blastocyst, trophoblast and what makes up the embryonic disk. Highlight that the trophoblast will differentiate and develops the amnion. Other key structures to mention are placenta and the umbilical cord

The Embryonic Period Week 3-Week 8 Key Developments Embryonic Layers Ectoderm Mesoderm Endoderm Highlight development of each part and what each will become according to the text.

The Embryonic Period Week 3-Week 8 Key organs and structures are forming including Heartbeat Eyes, nose and mouth Bone development Arm and leg buds Digestive system Identify specific week for each structure.

The Fetal Period Week 9-Birth The longest period of prenatal development Heartbeat can be heard Movement can be felt Responds to sounds Main impediment to viability is lung development Identify specific timeline development as important for the instructor and the class. Viability is important to mention. Interesting question to ask class is when fetus may feel pain. Or when they think there is brain activity

The Fetal Period Week 9-Birth Identify specific timeline development as important for the instructor and the class. Viability is important to mention. Interesting question to ask class is when fetus may feel pain. Or when they think there is brain activity

Prenatal Care Traditional Cultures and Beliefs Prenatal beliefs are impacted by generational wisdom of the time These beliefs can include Avoiding wine Specific types of meat Certain types of hot, cold food Witches Strong foods A mix of practical and cultural ideas for prenatal care Identify specific cultures for each belief system

Prenatal Care Science Driven Prenatal Care Some current science-driven prenatal methods are derived from traditional cultures which includes massages Current care can vary by ethnicity and SES Developing world less likely to receive prenatal care Current focus on diet, exercise, and teratogens

Map 2.1 Ethnic Variations in Prenatal Care within the United States How does prenatal care differ for White women compared with other ethnic groups? What economic factors might account for these variations?

Prenatal Care Diet Two key vitamins are iodine and iron Iodine deficiency tends to be a bigger issue in developing countries Iron is necessary for a healthy pregnancy It is important for women to drink fluids and expect increase in caloric intake of about 300 + calories

Prenatal Care Exercise Continued physical activity is encouraged during pregnancy Aerobic exercise encourages good cardiovascular health and positively benefits the fetus A Non-aerobic exercise called Kegel exercises are also encouraged Take moment to go more in depth of benefits of health for child and for mother. Also mention how too much could be detrimental

Prenatal Care Teratogens Teratogens are environmental and bodily conditions that could be harmful They can include tobacco, alcohol, prescription medications and other drugs The physical environment could also be a teratogen due to malnutrition or exposure to hazardous chemicals

Safety sign. Source: http://www.compliancesigns.com

Pregnancy Problems

Chromosomal Disorders Chromosomal disorders can occur because of an issue during meiosis This may cause too many or too few chromosomes in the cells of the zygote Two types of chromosomal disorders are: Sex chromosome disorders Disorder on the 21st chromosome (Down Syndrome)

Sex Chromosome Disorders Sex chromosomal disorder can result from extra X, an extra Y, or only an X and no second chromosome Common consequences of sex chromosome disorders include: Cognitive Deficit Abnormality in reproductive system at puberty

Down Syndrome Trisomy 21 Identifiable by physical characteristics Cognitive Deficits Speech problems Mental retardation Social development varies Lower life expectancy Mention specific physical and social development

Parental Age and Chromosomal Disorder Chromosomal disorders tend to NOT be passed from parent to child Relationship between maternal age and chromosomal disorders There may be a relationship between a father’s age and chromosomal disorders but it isn’t as clear

Figure 2.7 Chromosomal Disorders and Maternal Age Why does the risk rise so steeply after age 40? Source: Reproductive Medicine Associates of New Jersey, 2002

Teratogens Major teratogens exist in both developed and developing countries Malnutrition Infectious Disease Alcohol Tobacco

Teratogens Timing of Teratogens Teratogens can impact the developing fetus and embryo at any time There does appear to be a critical period of prenatal development centered in the embryonic period Mention more about critical timing of teratogens as well as time of exposure and how that can impact the development at different times

Teratogens Timing of Teratogens Mention more about critical timing of teratogens as well as time of exposure and how that can impact the development at different times

Teratogens Malnutrition Rural nature of half the world’s population impacts nutrition Children’s health could vary based on country or area of conception Common Teratogen worldwide is malnutrition Mention effects of anencephaly and spina bifida and folic acid deficits in relation to China

Teratogens Malnutrition Developed countries have food available but may have malnutrition May be deficient in specific vitamins or improper diet may lead to obesity Maternal obesity is linked to baby complications Prenatal nutrition can also cause prenatal problems Identify some specific baby complications or have class list some complications and problems from the reading and personal experience. Allows for class interaction

Teratogens Infectious Diseases Rubella (German Measles) Exposure during embryonic stage can lead to heart abnormalities and mental retardation Exposure during the fetal stage can lead to hearing problems and low birth weight Vaccination can help but Rubella remains widespread in less developed countries

Teratogens Infectious Diseases AIDS (Acquired Immune Deficiency Syndrome) Three strategies can help prevent transmission Effective medicines Cesarean sections for AIDS-infected moms Infant formula in place of breast feeding Good idea to have a discussion about which strategies could be employed in developing world that could be more effective. Possibly relate this to malnutrition as well especially regarding strategy number 3

Teratogens Drugs-Alcohol Widespread damage in developed countries Fetal Alcohol Spectrum Disorder Increased effects as child develops

Teratogens Drugs-Tobacco Maternal smoking increases risk of miscarriages, premature birth and low birth weight Infant effects include difficulty breathing and impaired heart functioning

Teratogens Drugs-Tobacco Childhood effects include poorer language skills, attention and memory problems and behavior problems Second hand smoke by fathers is also detrimental

Teratogens Drugs Malnutrition and diseases are common in developing countries Alcohol and tobacco are common in developed countries Prescription drugs can be damaging Other teratogens include non-prescription drugs, severe stress, pollution and radiation

Prenatal Diagnosis Ultrasounds-Uses high frequency sound waves Amniocentesis-Utilizes amniotic fluid Chorionic Villus Sampling-Utilizes cells from forming umbilical cord Be sure to identify why amniocentesis may be preferred over CVS and possible risks with each.

Infertility Causes For men three main causes For women many causes Too few sperm Quality of sperm Low motility For women many causes One is ovulation

Figure 2.9 Fertility and Maternal Age Why does fertility decline after the mid-twenties? Source: Reproductive Medicine Associates of New Jersey, 2002

Infertility Treatments Historical treatments of infertility included: Giving more attention to wife to achieve mutual orgasm Surgery on a woman’s anatomy Bloodletting Current treatments are more advanced

Infertility Treatments Many treatments utilize Assisted Reproductive Technologies (ART) Artificial Insemination Injects sperm into woman’s uterus Fertility Drugs Mimic hormones involved in ovulation In-vitro fertilization Ova removed and fertilized outside the womb then placed into uterus Specific information about multiples with Insemination and fertility drugs to match the photo

Utilize the map to discuss reasons for infertility in this portion of Central Africa. Also allows for discussion on if there could be such “regions” in other parts of the world. Also able to explore cultural variations in how infertility is viewed. Map 2.2 The “Infertility Belt” In certain countries in Central Africa, infertility rates are as high as 30%. The reasons for this are unclear although malnutrition and high rates of STIs are probable factors.