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A Healthy A Healthy PregnancyPregnancy

Unit FourUnit Four

Genetic Problems in Genetic Problems in Prenatal Prenatal

DevelopmentDevelopment

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ObjectivesObjectives Name and describe specific Name and describe specific

types of Birth Defectstypes of Birth Defects Discuss the causes of Birth Discuss the causes of Birth

DefectsDefects Identify how birth defects can Identify how birth defects can

be diagnosed and preventedbe diagnosed and prevented

Note:Note: 150,000 babies are born each 150,000 babies are born each

year with birth defectsyear with birth defects 1 out of 28 babies1 out of 28 babies

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Birth DefectsBirth Defects A A Birth DefectBirth Defect is an abnormality present at is an abnormality present at

birth, that affects the structure or function of birth, that affects the structure or function of the body.the body.

Premature BabiesPremature Babies are born before their are born before their development is complete (pregnancy less than development is complete (pregnancy less than 36 weeks or weigh less than 5.5 lbs). They are 36 weeks or weigh less than 5.5 lbs). They are vulnerable to infection, lung ailments and vulnerable to infection, lung ailments and other problems.other problems.

In some cases if prenatal development is not In some cases if prenatal development is not proceeding normally, a proceeding normally, a miscarriage miscarriage ( the ( the natural ending of a pregnancy before the fetus natural ending of a pregnancy before the fetus could possibly survive)could possibly survive) occurs. occurs.

A A stillbirthstillbirth is the natural ending of a is the natural ending of a pregnancy after 20 weeks.pregnancy after 20 weeks.

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Causes of Birth DefectsCauses of Birth Defects

Some birth defects are caused by Some birth defects are caused by Heredity Heredity and others by theand others by the Environment.Environment.

Heredity DefectsHeredity Defects are inherited are inherited from one or both parents.from one or both parents.

Environmental DefectsEnvironmental Defects are caused are caused by facors in he environment.by facors in he environment.

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Hereditary CausesHereditary Causes

Everyone has five or six Everyone has five or six imperfect imperfect recessive genesrecessive genes among thousands among thousands that make up the genetic blueprint.that make up the genetic blueprint.

Normal genesNormal genes are usually are usually dominantdominant over recessive genes.over recessive genes.

If If both parentsboth parents pass on the same pass on the same defective recessive gene for a defective recessive gene for a particular defect, the child will be particular defect, the child will be born with that defect.born with that defect.

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Hereditary DefectsHereditary Defects

Some hereditary Some hereditary defects are defects are inherited conditions inherited conditions that affect males that affect males only. only.

HemophiliaHemophilia, a , a condition that condition that affects blood affects blood clotting and clotting and Color Color BlindnessBlindness are such are such conditions.conditions.

Color blindness charts

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HemophiliaHemophilia HemophiliaHemophilia is a genetic disease: is a genetic disease:

Mutations on the X chromosome Mutations on the X chromosome result in low levels of blood clotting result in low levels of blood clotting factors. factors.

The mutations that cause low levels The mutations that cause low levels of clotting factor are carried of clotting factor are carried recessivelyrecessively on the X chromosome. on the X chromosome.

As women have two X As women have two X chromosomeschromosomes (XX(XX), the mutated gene would have to ), the mutated gene would have to be present on both chromosomes to be present on both chromosomes to cause the disease, and this is cause the disease, and this is exceedingly rare. exceedingly rare.

Since men have only one X Since men have only one X chromosome chromosome (XY(XY), one copy of the ), one copy of the mutated hemophilia gene is enough mutated hemophilia gene is enough to cause the disease, so males who to cause the disease, so males who inherit the gene willinherit the gene willbe affected.be affected.

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Cystic FibrosisCystic Fibrosis CauseCause- genetic- genetic DescriptionDescription--

Respiratory and Respiratory and digestive problemsdigestive problems

Below a Below a CF Lung CF Lung on lefton left compared compared to a to a Healthy Lung Healthy Lung on righton right

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Cystic Fibrosis - A Genetic Cystic Fibrosis - A Genetic DisorderDisorder Cystic FibrosisCystic Fibrosis is a genetic is a genetic

disease, meaning it is disease, meaning it is caused caused by a defect in the person's by a defect in the person's genes.genes.

Cystic FibrosisCystic Fibrosis is a chronic, is a chronic, frequently fatal, progressive, frequently fatal, progressive, genetically genetically (inherited)(inherited) disease disease of the body's mucus glands. of the body's mucus glands. Cystic Fibrosis primarily Cystic Fibrosis primarily affects the affects the respiratory and digestive systerespiratory and digestive systemsms in children and young adults . in children and young adults .

Cystic Fibrosis affects the Cystic Fibrosis affects the body's ability to move salt and body's ability to move salt and water in and out of cells. This water in and out of cells. This defect causes the lungs and defect causes the lungs and pancreaspancreas to secrete thick to secrete thick mucus, mucus,

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Rh Factor - Genetic Rh Factor - Genetic DefectDefect

A blood test is also A blood test is also used to check the used to check the RhRh factorfactor in the blood. in the blood.

A person’s blood is A person’s blood is either:either:

1.1. Rh positive -Rh positive - having a having a certain protein or certain protein or

2.2. Rh negative -Rh negative - not not having that proteinhaving that protein

Problems can arise if he Problems can arise if he mother’s blood lacks mother’s blood lacks the protein and the the protein and the fetus’s blood has it. fetus’s blood has it. ( ( the fetus may inherit the fetus may inherit this blood factor from this blood factor from the fatherthe father).).

The mothers blood will The mothers blood will produce anti-bodies produce anti-bodies that attack the protein that attack the protein in the fetus’s blood as in the fetus’s blood as though it were a germ.though it were a germ.

Doctors can inject a Doctors can inject a chemical into the chemical into the mother o prevent the mother o prevent the problem from problem from arisingarising..

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Other Genetic Other Genetic DisordersDisorders Down’s SyndromeDown’s Syndrome

May include mental May include mental retardation, delayed retardation, delayed development, heart defectsdevelopment, heart defects

Chromosomes are made up Chromosomes are made up of DNA and protein & are of DNA and protein & are located in the nucleus of located in the nucleus of each cell. each cell.

Because chromosomes are Because chromosomes are carriers of genetic material, carriers of genetic material, abnormalities in abnormalities in chromosome structure chromosome structure (such as missing or extra (such as missing or extra copies or gross breaks), can copies or gross breaks), can result in disease.result in disease.

Special therapy and schooling are part of treatment for Down’s Syndrome Children

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Down Down syndromesyndrome

Down syndromeDown syndrome or trisomy 21 is a or trisomy 21 is a common disorder common disorder that occurs when a that occurs when a person has three person has three copies of copies of chromosome 21. chromosome 21. One in every 650 One in every 650 births has this births has this condition.condition.

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Cleft Lip / Cleft PalateCleft Lip / Cleft Palate A A cleft lipcleft lip is a separation of the two sides of is a separation of the two sides of

the lip. The separation often includes the the lip. The separation often includes the bones of the upper jaw and/or upper gum.bones of the upper jaw and/or upper gum.

A A cleft palatecleft palate is an opening in the roof of the is an opening in the roof of the mouth in which the two sides of the palate did mouth in which the two sides of the palate did not fuse, or join together, as the unborn baby not fuse, or join together, as the unborn baby was developing was developing

One of every 700 newborns is affected by cleft One of every 700 newborns is affected by cleft lip and/or cleft palate. lip and/or cleft palate.

Cleft lip and cleft palate are birth defects, Cleft lip and cleft palate are birth defects, which occur very early in pregnancy. The which occur very early in pregnancy. The majority of clefts appear to be due to a majority of clefts appear to be due to a combination of genetics and environmental combination of genetics and environmental factors. factors.

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Cerebral PalsyCerebral Palsy Cerebral Palsy (CP)Cerebral Palsy (CP) is a is a

term used to describe a term used to describe a group of disorders group of disorders affecting body movement affecting body movement and muscle co-ordination. and muscle co-ordination.

Development of the brain Development of the brain starts in early pregnancy starts in early pregnancy and continues until about and continues until about age three. Damage to the age three. Damage to the brain during this time may brain during this time may result in cerebral palsy. result in cerebral palsy.

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MUSCULAR DYSTROPHYMUSCULAR DYSTROPHY Muscular Dystrophy Muscular Dystrophy

(MD)(MD) is the name of a is the name of a group of muscle group of muscle disorders that are disorders that are characterized by characterized by progressive weakness progressive weakness and wasting of the and wasting of the voluntary muscles that voluntary muscles that control body movement. control body movement. As muscle tissue weakens As muscle tissue weakens and wastes away, it is and wastes away, it is replaced by fatty and replaced by fatty and connective tissue.connective tissue.

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MUSCULAR DYSTROPHYMUSCULAR DYSTROPHY

CauseCause- - Heredity [ female Heredity [ female male]male] Most types of MD are Most types of MD are

hereditary . The most hereditary . The most common form is transmitted common form is transmitted by female carriers of the by female carriers of the gene but affects only males.gene but affects only males.

DescriptionDescription- - Weakness and shrinkage of Weakness and shrinkage of

the musclesthe muscles Death before adulthoodDeath before adulthood

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PKUPKU

What isWhat is Phenylketonuria (PKU)?Phenylketonuria (PKU)? PKU is a genetic disorder which PKU is a genetic disorder which

prevents the normal use of protein prevents the normal use of protein food. Mental retardation can food. Mental retardation can result. To be affected by this result. To be affected by this hereditary condition (carried on a hereditary condition (carried on a recessive gene) a child must have recessive gene) a child must have two copies of the defective gene two copies of the defective gene (one from each parent).(one from each parent).

The condition can be treated with The condition can be treated with a high degree of success if a high degree of success if diagnosed shortly after birth. A diagnosed shortly after birth. A special diet can reduce or prevent special diet can reduce or prevent brain damage.brain damage.

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The Genetics of PKUThe Genetics of PKU Genes can sometimes contain mistakes Genes can sometimes contain mistakes

so that the cell can't read them properly. so that the cell can't read them properly. We can call this a "non-working gene". We can call this a "non-working gene".

The gene that is important in PKU is The gene that is important in PKU is located on the chromosome pair number located on the chromosome pair number 12. 12.

People with PKU have two non-working People with PKU have two non-working copies of this PKU gene. One copy they copies of this PKU gene. One copy they inherited from mom, and the other from inherited from mom, and the other from dad. Usually, parents don't even know dad. Usually, parents don't even know they are carriers of PKU until they have they are carriers of PKU until they have a baby who has PKU. a baby who has PKU.

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Sickle-Cell AnemiaSickle-Cell Anemia

Sickle cell anemiaSickle cell anemia occurs when a person occurs when a person inherits two abnormal inherits two abnormal genes (one from each genes (one from each parent) that cause their parent) that cause their red red bloodblood cells to cells to change shape. Instead change shape. Instead of being flexible and of being flexible and round, these cells are round, these cells are more rigid and curved more rigid and curved in the shape of the in the shape of the farm tool known as a farm tool known as a sickle sickle

11. Normal Red Blood Cells. Normal Red Blood Cells2. Sickled Red Blood Cells2. Sickled Red Blood Cells

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Sickle Cell AnemiaSickle Cell Anemia Sickle cell anemiaSickle cell anemia is a is a

hereditaryhereditary disorder that disorder that mostly affects people of mostly affects people of AfricanAfrican ancestry, but ancestry, but also occurs in other also occurs in other ethnic groups, including ethnic groups, including people who are of people who are of Mediterranean and Mediterranean and Middle Eastern descent .Middle Eastern descent .

People with sickle cell People with sickle cell anemia can experience anemia can experience complications from blood complications from blood circulation and infection-circulation and infection-fighting problems .fighting problems .

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Tay-Sachs Tay-Sachs DiseaseDisease

Tay-Sachs diseaseTay-Sachs disease affects children who affects children who inherit two copies of an inherit two copies of an altered gene from their altered gene from their carrier parents. carrier parents.

Carriers of Carriers of Tay-Sachs Tay-Sachs diseasedisease are not affected are not affected themselves, because themselves, because they have a working they have a working gene as well as an gene as well as an altered one. altered one.

Carrier parents have a Carrier parents have a one-in-four chance of one-in-four chance of having an affected child, having an affected child, a one-in-two chance of a one-in-two chance of having a child who is an having a child who is an unaffected carrier and a unaffected carrier and a one-in-four chance of one-in-four chance of having a child who having a child who doesn't carry any altered doesn't carry any altered genesgenes..

Infants with Tay-Sachs disease Infants with Tay-Sachs disease appear to develop normally for the appear to develop normally for the first few months of life. Then, as first few months of life. Then, as nerve cellsnerve cells become distended with become distended with fatty material, a relentless fatty material, a relentless deterioration of mental and physical deterioration of mental and physical abilities occurs. The child becomes abilities occurs. The child becomes blindblind, , deafdeaf, and unable to , and unable to swallowswallow. . Muscles begin to Muscles begin to atrophyatrophy and and paralysisparalysis sets in. sets in.

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Spina BifidaSpina Bifida The risk of having a The risk of having a

baby with baby with spina spina bifidabifida is 2-3 percent. is 2-3 percent.

It is well established It is well established that taking that taking folic acidfolic acid prior to pregnancy as prior to pregnancy as well as in the first well as in the first trimester will trimester will decrease decrease spina bifidaspina bifida in the general in the general population by 70 population by 70 percent. percent.

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Spina Spina BifidaBifida

Spina bifidaSpina bifida usually is an usually is an isolated birth isolated birth defect. Although defect. Although scientists believe scientists believe that genetic and that genetic and environmental environmental factors may act factors may act together to cause together to cause this.this.

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Genetic CounselingGenetic Counseling

Some genetic or Some genetic or chromosomal defects can chromosomal defects can be predicted by genetic be predicted by genetic counseling.counseling.

It tells parents in It tells parents in advance the statistical advance the statistical odds that their children odds that their children will have certain diseases will have certain diseases or defects.or defects.

It explains options and It explains options and risks.risks.

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Prenatal TestsPrenatal Tests

If a woman is If a woman is pregnant, her doctor pregnant, her doctor may request tests to may request tests to determine birth determine birth defects.defects.

UltrasoundUltrasound is a is a technique of using technique of using sound waves to make sound waves to make a video of an unborn a video of an unborn baby to check for baby to check for specific health specific health problems.problems.

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Prenatal TestsPrenatal Tests

Amniocentesis Amniocentesis is is the process of the process of withdrawing a withdrawing a sample of he sample of he amniotic fluid amniotic fluid surrounding the surrounding the unborn baby with a unborn baby with a special needle and special needle and testing that fluid for testing that fluid for indications of specific indications of specific birth defects or other birth defects or other health problems.health problems.