1. Unit III
Genetic/Developmental, Childhood, and Mental Health Diseases and Disorders 1

2. Genetic and Developmental Diseases and Disorders
Chapter 19
Genetic and Developmental Diseases and Disorders 2

3. Anatomy and Physiology
Cell nucleus
46 chromosomes – 23 pairs
Somatic cells reproduce through mitosis
Double then divide—produce identical cells
Germ cells (sex cells) reproduce through meiosis—result in each cell carrying only half the number of chromosomes.
Haploid cells carrying 23 chromosomes 3

4. Anatomy and Physiology
Normal females
Sex chromosome is Xxthe ovum undergoes meiosis and divides into two separate X chromosomes
Normal male
Sex chromosomes is o spearate chromosomes, one X and one Y, so the male can give an X or Y
germ cells(sperm) undergo meiosis and divide into
Male sperm can be X or Y – male determines sex of child
Chromosomes can be visualized by karyotyping
Sex chromosomes can be evaluated by buccal smear 4

5. X Y
X bearing sperm
Y bearing sperm X X XY XX

6.                                     
How are Barr Bodies formed?
Any cell with more than one X chromosome will exhibit (n – 1) Barr bodies during interphase.  Each excess X chromosome will form one Barr body. This means that 46,XX women will have cells that exhibit one Barr body, while the cells from a 46, XY male will not exhibit any Barr bodies sex chromosomes can be evaluated by a buccal smear

7. Anatomy and Physiology
Female X germ cell is much larger than male Y cell and carries more genetic information
Chromosomes are made of deoxyribonucleic acid (DNA) and in a specific order; each is called a gene
Chromosomes (one from each parent) pair up during fertilization; these paired genes are alleles 7

8. This normal karyotype shows 23 pairs of chromosomes:
Pairs 1-22 are autosomes (they do not determine sex)
Pair 23 are the sex chromosomes (XX female, XY male)

10. X chromosome
Has over 1,500 genes
Most genes on the X chromosome do not have corresponding alleles on the Y chromosome
Y chromosome
Has only 231 protein-encoding genes
Some genes are unique only to the Y chromosome
The human male is hemizygous for X-linked traits because he only has one copy of each X chromosome gene
Some recessive X-linked traits expressed in males include:
Red-green colorblindness
Hemophilia

11. Anatomy and Physiology
Each gene in an allele can be dominant or recessive
Homozygous – matched alleles such as BB or bb
Heterozygous – unmatched alleles such as Bb
Expression of a physical trait is called phenotype 11

12. 50% chance unaffected carrier (cf allele inherited from either parent)
+ = wild type
allele
cf = cystic fibrosis
allele
Carrier parents
For each child conceived
25% chance
unaffected
noncarrier
50% chance unaffected carrier (cf allele inherited from either parent)
25% chance
affected

13. aabbcc AABBCC
Number of dominant alleles

14. AABB
aabb

15. Anatomy and Physiology p.477
Abnormalities can be due to:
Chromosomal disorder
Genetic disorder
Environmental factors
Combination of above
Individuals acquire abnormal genes in two ways:
Mutation of gene during meiosis
Passage of abnormal gene from parents (heredity) 15

16. Most if not all characteristics and disorders considered “inherited” actually reflect input from the environment as well as genes
Polygenic traits
Determined by more than one gene
Examples include height, skin color, and eye color
Blood type O without genotype ii. Due to homozygous recessive expression of another gene, therefore blood types A and B are not possible – called Bombay phenotype
Multifactorial traits
Traits molded by one or more genes plus environmental factors
Examples include height and skin color
Common diseases such as heart disease, diabetes mellitus, hypertension, and cancers are multifactorial

17. Deviations from the normal chromosome number of 46 produce syndromes because of the excess or deficit of genes
Chromosome number abnormalities may involve single chromosomes or entire sets of chromosomes
Euploid is a normal chromosome number

18. Anatomy and Physiology
Genetic disorders are passed to offspring in four ways:
Autosomal dominant
Autosomal recessive
Sex-linked dominant
Sex-linked recessive 18

19. Anatomy and Physiology p. 480
Approximately 2% of newborns are born with congenital anomalies
Causes:
60% unknown cause
20% genetic
10% chromosomal
10% environmental 19

20. Diagnostic Tests Fetal ultrasound Amniotic fluid Maternal blood
Detects malformations
Amniotic fluid
Reveals genetic and chromosomal disorders
Maternal blood
Reveals abnormal fetal substances 20

21. MD sex linked generally passed from mother to son the affected muscles are unable to store needed protein. Malnourished muscle are unable to store needed protein. Malnourished muscle fibers die and are replaced with fat and connective tissue. These fibers are unable to function as muscle fibers.

22. Musculoskeletal Muscular dystrophy (MD)---
Genetic degeneration or weakening of muscles
Duchenne’s MD
Most common type
Cause:
Sex-linked disorder passes mother to son
Symptoms:
Onset between 2 and 5 years of age
Waddling gait, toe walking, lordosis, Gower’s maneuver p. 481
Treatment:
No cure—usually in w/c by age 9 . life expectancy late teens or early 20s
Physical therapy, orthopedic devices, exercise helpful 22

23. Musculoskeletal p. 481 Congenital hip dislocation (CHD)
Abnormal hip joint resulting in femoral head slipping out of normal position
Cause:
Improper positioning in uterus, maternal hormones
Symptoms:
Asymmetrical folds of affected thigh
Difference in leg length
Limited abduction – Ortolanti’s sign
Treatment:
Closed or surgical reduction of femoral head 23

24. Musculoskeletal Clubfoot Also known as talipes equinovarus
Common congenital abnormality of foot
Cause:
Unknown—thought to be due to genetic factors or fetal positioning
Symptoms:
Foot or feet turn inward with toes pointed downward and heel drawn upward
Treatment:
Gradual straightening
Cast
Splints 24

25. Musculoskeletal p. 483 Osteogenesis imperfecta
Most cases of osteogenesis imperfecta have an autosomal dominant pattern of inheritance, which means one copy of the altered gene in each cell is sufficient to cause the condition
Osteogenesis imperfecta
Abnormally brittle bones leading to fractures
Cause:
Inherited gene mutation
Symptoms:
Frequent bone fractures
Blue coloration of sclera of eyes
Treatment:
No cure
Tendency for bones to fracture often disappears by adulthood 25

26. Neurologic Hydrocephalus
Abnormal accumulation of cerebrospinal fluid in brain due to obstruction
Cause:
Congenital defect, infection, tumor
Symptoms:
Rapid enlargement of infant head and bulging eyes
Tight scalp and prominent head veins
Shrill, high-pitched cry
Treatment:
Surgical correction with shunt placement page 483 26

27. Neurologic Cerebral palsy Congenital bilateral paralysis Cause:
Inadequate blood or oxygen supply to brain during fetal development, birthing process, or infancy
Symptoms:
Hyperactive reflexes and rapid muscle contraction
Muscle weakness with scissors gait 27

28. Neurologic Cerebral palsy Treatment: No cure
Physical and speech therapy
Orthopedic cast, braces, and surgery
Anticonvulsants
Muscle relaxants
No cure 28

29. Neurologic Spina bifida---------- 483-(484 look at image)
Congenital disorder
Opening in spinal column
Cause:
Unknown
Risk factors include maternal radiation, virus, genetic factors
Symptoms:
Differ with form of disease
Forms of spina bifida
Spina bifida occulta
Meningocele
Myelomeningocele—most serious
Treatment: Surgery 29

30. Neurologic p. 484-485 Huntington’s disease
Genetic defect of chromosome 4
Cause:
Genetic – if one parent has disorder, 50% chance in offspring
Symptoms:
Behavioral changes
Unsteady gait
Increasing dementia
Treatment:
No cure
Medications reduce symptoms

31. Eventually, a person with Huntington's disease requires help with all activities of daily living and care. Late in the disease, he or she will likely be confined to a bed and unable to speak. However, he or she is generally able to understand language and has an awareness of family and friends.
Common causes of death include:
Pneumonia or other infections
Injuries related to falls
Complications related to the inability to swallow

32. Cardiovascular p. 485 Congenital heart defects
Heart and related vessels are most common sites of congenital defects
Defects can range from small to quite large
Collectively, these malformations are called congenital heart defects

33. Cardiovascular Congenital heart defects (continued) Cause: Symptoms:
Unknown, but genetic tendency is strongly suspected
Symptoms:
Vary from mild (asymptomatic) to extreme with cyanosis, breathing difficulty, and heart murmurs
Diagnosis:
Electrocardiogram
Physical examination
Treatment:
Early diagnosis
Surgery to correct the defect

34. Cardiovascular Congenital heart defects (continued)
Atrial septal defect
Opening between right and left atria
Commonly due to foramen ovale not closing at birth
Causes increased workload on right heart—blood from the left atria can go back through ovale to R atria to be pumped to lungs again—this repumping causes increased workload

35. Cont. Ventricular septal defect Most common heart defect—25%
Hole between right and left
Blood shunted from left to right
Causes increased workload on right heart
The ductus arteriosus like the foramen ovale, normally closes off shortly after birth. If the structure does not close, or remains patent, the condition is called patent ductus arteriosus

36. Cardiovascular Congenital heart defects (continued)
Patent ductus arteriosus--—occurs twice as frequently in girls as boys
Connection between pulmonary artery and aorta that does not close off after birth
Blood shunts from aorta to pulmonary artery
Causes increased workload on heart and pulmonary system
Coarctation of aorta
Stricture or narrowing of aorta
Causes increased blood pressure proximal to narrowingally—lower blood pressure dist
Causes increased workload on heart

37. Cardiovascular Congenital heart defects (continued)
Tetralogy of Fallot page 487
One of the most serious of congenital defects
Combination of four problems
Pulmonary valve stenosis—opening too small
Right ventricle hypertrophy—R ventricle enlarges due to increased effort of pushing blood through the stenotic pulmonary valve
Ventricle septal defect—blood can flow bac into R ventricle when L ventricle contracts
Abnormal placement of aorta--aorta opens OVER the ventricular septal defect 37

39. Tetralogy of Fallot Babies are truly blue babies
Tetralogy of Fallot Babies are truly blue babies. Cyanosis increases with age, and clubbing of fingers and toes becomes evident. Older children will rest in a squatting position to breath easier. Other symptoms are growth retardation, severe dyspnea with exercise, and frequent respiratory infections.

40. Blood Sickle cell anemia Hemophilia Chronic hereditary form of anemia
(discussed in detail in Chapter 7)
Chronic hereditary form of anemia
Predominantly affects black population
Hemophilia
X-linked hereditary disorder passed from mother to son 40

41. Digestive p. 488
Digestive disorders both genetic and developmental range from mild to severe
Many are diagnosed at birth
Some are incompatible with life and must be corrected immediately 41

42. Digestive Developmental malformations Maternal rubella
Several developmental malformations occur in the digestive system
Cause:
Unknown
Might be related to genetic tendencies
Might be related to maternal risk factors
Maternal rubella
Poor maternal nutrition
Smoking
Alcoholism 42

43. Digestive Developmental malformations (continued)
Meckel’s diverticulum
Outpouching of diverticulum of the ileum—may be asymptomatic the entire life and only found on autopsy
Esophageal atresia
Abnormal esophagus
(atresia—is the congenital absence or closure of a normal opening or lumen in the body and can occur in a variety of areas)
Congenital diaphragmatic hernia
A hole in the diaphragm—abdominal organs might herniate through this opening 43

44. Digestive Developmental malformations (continued) p. 489
Imperforate anus
Failure of the anus to connect to the rectum—infant will not pass stool. Abdominal pain and cramping with vomiting. Must be surgical corrected
Cleft lip—affects nursing, speech, increases respiratory and middle ear infections
One or more splits in upper lip
Affects boys more frequently than girls
Treatment:
Surgical repair 44

45. Digestive Developmental malformations (continued)
Cleft palate—hard palate (roof of mouth) does not close
More serious than cleft lip
Involves roof of mouth
Treatment:
Surgical repair
Again causes problems with feeding, speaking, increases respiratory infections and middle ear infections 45

46. Cleft Lip and Palate
Photo courtesy Dr. Joseph Konzelman, School of Dentistry, Medical College of Georgia 46

47. Cleft Lip and Palate
Photo courtesy Dr. Joseph Konzelman, School of Dentistry, Medical College of Georgia 47

48. Digestive Genetic digestive disorders p. 490 Pyloric stenosis
Narrowing of lower end of stomach
Common anomaly of digestive tract
Symptoms:
Projectile vomiting
Treatment:
Pylorotomy—incising and suturing the pyloric sphincter muscle. 48

49. Pyloric Stenosis 49

50. Digestive Genetic digestive disorders (continued)
Hirschsprung’s disease—seen more often in boys and those with Downs syndrom
Absence of nerves in segment of colon
Usually sigmoid colon—there is no peristalsis in this area.
Symptoms:
Chronic constipation
Abdominal distention—massive distention of the colon
Treatment:
Surgical removal of affected segment
Temporary colostomy may be necessary to allow adequate healing of colon 50

51. Digestive Genetic digestive disorders (continued)
Phenylketonuria (PKU)
Genetic disorder involving faulty metabolism of protein phenylalanine
Diagnosis by blood test 72 hours after birth
Mandatory in United States
Lack of treatment can result in mental disability 51

53. Untreated PKU

54. Hypospadias Chordee Epispadias
Urinary all can lead to problems with elimination of urine and can lead to difficulty with intecourse
Hypospadias
Abnormal congenital opening of male urinary meatus on under surface of penis—it can be severe with locations midshaft or near the scrotum. It occurs in 1 in 250 boys
Chordee
Abnormal fibrous band of tissue—abnormal downward curvature
Epispadias
Abnormal congenital opening of male urinary meatus on upper surface of penis
Cause of these conditions:
Unknown
Treatments: No treatment to surgical repair 54

55. Urinary
Wilms’ tumor
Most common solid tumor affecting children and infants
Cause:
Thought to be genetic
Highly malignant
Usually replaces one whole kidney
Symptoms:
Asymptomatic until large enough to feel in child’s stomach
Treatment:
Chemotherapy
Surgery 55

56. Reproductive Cryptorchidism Turner’s syndrome
Condition of undescended testes (discussed in Chapter 17)
Turner’s syndrome
Affects females; ovaries are abnormal or absent
Cause:
Chromosomal disorder
Females have only one X chromosome
Rather than two XX chromosomes
Symptoms:
Failure to develop normal secondary sex characteristics
Treatment:
Symptoms can be reduced with growth with hormones and estrogen therapy 56

57. Reproductive Klinefelter’s syndrome—affects 1 in 1000
Affects males; do not develop secondary sex characteristics
Cause:
Chromosomal disorder
Affected males have extra X chromosome—so XXY
Symptoms:
Not diagnosed until puberty due to abnormal male sexual development
Sterility, abnormally small penis and testes
General appearance of a eunuch – tall, slender body and long legs
Treatment:
Testosterone treatment and psychological counseling 57

58. Other Developmental Disorders
Autism
Developmental disorder characterized by difficulty communicating and in forming relationships
Cause:
Unknown
Symptoms:
Blank facial expression
Involved with self – inaccessible to others
Treatment
Behavioral therapy
Depends on severity and symptoms present 58

59. Other Developmental Disorders
Stuttering
Also known as stammering
Developmental speech disorder
Cause: anxiety with addressing others
Symptoms:
Hesitancy of starting and finishing words
Prolonged pauses between words
Treatment:
Behavior modification
Positive reinforcement 59

60. Multisystem Diseases and Disorders p. 494
Cystic fibrosis
Hereditary disorder that affect all exocrine glands
Cause:
Hereditary recessive disorder
Symptoms:
Affects all exocrine glands leading to viscous secretions
Treatment:
Postural drainage
Chest-clapping
Antibiotics
Bronchodilators
Expectorants
Oxygen 60

61. Multisystem Diseases and Disorders
Down syndrome—p. 494
Also called trisomy 21 – a condition of having 3 chromosomes instead of the normal 2 in the 21st position of the chromosome chain
Symptoms:
Mild to severe mental disability
Flat nasal bridge Low-set ears
Slanted eyes Epicanthus
Thick, protruding tongue
Abnormal extremities
Organ defects
Treatment:
Highly individualized to maximize mental and physical abilities 61

62. Trauma Failure to thrive—p. 495
Lack of physical growth and development in infant or child
Cause:
Disturbance in mother–child relationship or failure to bond
Symptoms:
Weight loss or failure to gain weight
Anorexia, vomiting, diarrhea
Irritability
Rag-doll limpness 62

63. Trauma Failure to thrive (continued) Symptoms: Treatment:
Unresponsiveness to affection
Avoidance of eye contact
Stiffening when cuddled
Treatment:
Teaching of mothering and nurturing behaviors to mother/parents
Promotion of self-esteem 63

64. Trauma Fetal alcohol syndrome
A group of symptoms and birth defects in an infant born to a mother who consumed alcohol during pregnancy
Symptoms:
Varying degrees of mental disability
Decreased physical development
Irritability in infants
Hyperactivity in older children
Microcephaly
Increased incidence of ventricular septal defects 64

65. Trauma Congenital rubella syndrome
Transmission of rubella virus to unborn fetus
Can cause spontaneous abortion or major birth defects
The most common defects are:
Microcephaly
Learning disorders
Deafness
Abnormal growth
Heart defects
Ocular lesions
Prevention:
Immunization
No pregnancy for 3 months after immunization 65

66. Rare Diseases Anencephaly Achondroplasia Tay-Sachs disease
Absence of brain or cranial vault
Not compatible with life
Achondroplasia
Decreased long bone growth leading to type of dwarfism—(what we think of as “little people”
Tay-Sachs disease
Genetic error in lipid metabolism resulting in accumulation of toxins in brain 66