The Biological and Environmental causes of developmental disabilities

1. CHAPTER 1
THE BIOLOGICAL AND ENVIRONMENTAL
CAUSES OF DEVELOPMENTAL
DISABILITIES
CABOQUIN, JESIELYN
CAHINOD, JOHN PAUL
CARZON, LYRA JANE
CHANTENGCO, ALTHEA
COBACHA, SHEILA MAE
DELA CRUZ, JUVY

2. THE BASIC CONCEPTS OF HUMAN
REPRODUCTION
HEREDITY
Is the mechanism for the transmission of
human characteristics from one generation to the
next. Each person carries a genetic code or genome
, a complete set of coded instruction for making and
maintaining an organisms.
The nucleus inside the cell contains a
complete set of the body’s genome that is twisted
into forty-six packets of threadlike microscopic
structures called chromosomes.
Inside the chromosomes is the long
threadlike molecule and genetic substance called
the deoxyribonucleic acid or DNA. The DNA is a
complex molecule that contains the genome . The
DNA molecule consists of two strands of twisted
ladder-shape structure called the double helix that
wrap around each other. DOUBLE HELIX OF
DNA

3. The double helix was discovered in 1953 by American
Biochemist James Watson and British Francis Crick.
Gene is a specific sequence of the four nucleotide bases
whose sequences carry the information for constructing
proteins. Proteins provide the structural components of the
cells tissues and enzymes for essential biochemical
reactions.
SOME PRINCIPLES OF GENETIC DETERMINATION
Dominant- receives genes principles. If one gene of the pair
is dominant and one is recessive the dominant gene exerts
its effect, overriding the potential influence of the recessive
genes.
Sex-linked genes principle. Females have two X sex
chromosomes and males have an X and Y sex
chromosomes in their respected karyotypes. When one X
female chromosomes combines with the X male
chromosomes, the XX chromosomes results that make the
organism a female. Meanwhile, when one female X
chromosomes combines with the Y male chromosomes, the
XY chromosomes results that make the organisms a male.

4. Polygenic inheritance principle. Poly (many) genic (genes) inheritance
describes the interaction of many genes to produce a particular
characteristics.
Genotype refers to the person’s genetic heritage or the actual genetic
material. The genotype is established at conception during the process
of fertilization and usually remains constant and does not change.
Phenotype refers to the person’s observable traits that may be used to
draw inferences about genotype. The phenotype is the observable result
between the genotype and the environment.
THE BIOLOGICAL SOURCES OF DEVELOPMENTAL DISABILITIES
Basic terms in human reproduction
Gametes are the human reproduction cells which are created in the
reproductive organs. The ovaries of the female produce the ovum (ova)
or egg cells while the testicles or testes of the male produce the
spermatozoa or sperm.

5. Meiosis is the process of cell division in which each pair of chromosomes in the
cell separates, with one member of each pair going into each gamete or
daughter cell. Thus, each gamete, the ovum and the sperm, has a twenty three
unpaired chromosomes.
The ovum is the only about one-fourth the size of a period, but is the largest
cell in the human body. When a female is born, she already has about 400,000
immature ova in her two ovaries. In contrast to the ovum, the sperm, which is
the tadpole like and only one six hundredth (1/600th) inch from head to tail is
one of the smallest cells in the body.
CRITICAL PERIODS AND DEVELOPMENTAL VULNERABILITY DURING
PREGNANCY
Vulnerability refers to how susceptible the organisms is to being injured or
altered by a traumatic incident. A traumatic incident includes such board
occurrences as teratogens toxic agents, cell division mutation and other
deviations from the usual sequence development.
Deviancy from the normal course of prenatal development skills to the
occurrences of developmental disabilities.

6. THE COURSE OF PRENATAL DEVELOPMENT
The Germinal Phrase. The initial stage of prenatal development covers the
first two weeks after fertilization. The three significant developments during
this phrase are the creation of zygote, continuous cell division/ cell and
tissue differentiation and implantation or attachment of the zygote to the
uterine wall.
3 SIGNIFICANTS DEVELOPMENTS
1. CREATION OF ZYGOTE. Reproductive begins with the fertilization of a
female’s ovum by a male sperm.
Ovulation occurs once every twenty-eight days or so, as an ovum out of
hundreds of ova matures and the single ripe ovum bursts from its follicle.
Fertilization takes place with the union of the genetic materials in the ovum
and sperm cells.
Zygote is the new cell which results from the transmission of the genetic
materials twenty-four to thirty hours after fertilization.

7. 2. CONTINUOUS CELL DIVISION AND CELL TISSUE DIFFERENTATION.
Chemical reactions occur that cause the zygote to divide repeatedly and
generate new cells and tissues of different types.
Cell division occurs very rapidly in the first few days and progresses with
considerable speed.
Cell differentation continues as the inner and outer layers of the organism are
formed. The inner layer of cells which develops into the embryo later on is
called blastocyst.
Blastocyst inner layer of cells which develop into the embryo later on.
Trophoblast outer layer of cells that provides nutrition and support for the
embryo.
3. IMPLANTATION OR ATTACHMENT OF THE ZYGOTE TO THE UTERINE WALL.
Implantation starts on the sixth to the seventh day when the blastocyst starts to
attach itself to the uterine wall.
WHAT CAN GO WRONG DURING THE GERMINAL PHASE?
Genetic disorder can be transmitted such as:

8. 1. DOMINANT AND RECESSIVE DISEASES LIKE:
Tay Sach’s Disease
Genetic mutation

9. 2. SEX-LINKED INHERITANCES SUCH AS:
Lesch Nyhan Syndrome
CHARACTERISTICS OF FRAGILE X SYNDROME FOR MALES

10. 3. POLYGENIC INHERITANCE 4. CHROMOSOMAL DEVIATIONS
5. SEX CHROMOSOMAL ANOMALIES LIKE:
Klinefelter Syndrome

11. 6. CRANIAL OR SKULL MALFORMATION SUCH AS:
Anencephaly
SIGNIFICANT DEVELOPMENTS IN THE GERMINAL PERIOD EMBRYONIC
PHASE
The second phase of human development occurs from the end of the
germinal phase to the second month of pregnancy. The mass of cells is now
called the embryo.
3 MAIN PROCESS DURING THIS PHASE:
1. INTENSIFICATION OF CELL DIFFERENTIATION:
A. ECTODERM- outermost layer of cells that will develop into the surface
body parts.
B. MESODERM- the middle layer that will develop into the body parts
surrounding the internal areas.

12. C. ENDODERM- the inner layer of cells that will develop into the epithelium.
2. DEVELOPMENT OF THE LIFE SUPPORT SYSTEM- As the embryo's three
layers of cells develop, the life support system develop from the embryo for
the transfer of substances from the mother to the zygote and vice versa.
3. ORGANOGENESIS- is the process of organ formation and the appearance of
body organs during the first two months.
WHAT CAN GO WRONG DURING THE EMBRYONIC PHASE?
THE FETAL PHASE
 The third phase cover seven months that lasts from the third to ninth
month of pregnancy on the average.
CAUCASIAN BABY

13. WHAT CAN GO DURING THE FETTAL PHASE?
BIRTH OF INFANT after full gestation for 38 weeks, the fetus leaves the
intrauterine environment of the mother’s womb and begins life in the
outside world.
Normal delivery, lateral flexion
WHAT CAN GO WRONG DURING THE BIRTH PROCESS?

14. PHYSICAL TRAUMA OR MECHANICAL INJURY- during birth may injure or
damage the brain and impare intellectual functioning.
PRECIPITOUS BIRTH where labor is short (less than 2 hours) skull
molding that should be slow and smooth may affect and injure the brain.
BREECH BIRTH where the buttocks instead of the head presents itself first
poses substantial danger because the head reaches the pelvic girdle during
the later stages of labor when there is more pleasure exerting on it.
2. ANOXIA OR ASPHYXIA- occurs in breech delivery and deprives the infant
adequate supply of oxygen for a period long enough to damage the brain.
WHAT IS NEW BORN SCREENING?
PRINCIPLES OF NORMAL DEVELOPMENT IN INFANCY AND EARLY
CHILDHOOD
The general principles of normal development are useful guides in
observing the presence of such deviations.

15. 1. Normal development progresses in orderly step-by-step sequences.
2. All areas of development are interrelated.
3. The skills acquired earlier determine how well later skills will be learned.
4. Although there are developmental milestones in each of the growth areas,
children manifest individual differences in their rate of development. Each
child develops at his or her own pace.
GROSS MOTOR SKILLS
ACTIVITY APPROX.
AGE
ACTIVITY APPROX.
AGE
Raises chin while lying
on stomach
1 mo. Walks alone unsupported 18 mos.
Raises chest while
lying on stomach
2 mos. Sits self in small chair 18 mos.
Reaches for object but
misses
3 mos. Walks carrying large object 20 mos.
Head set forward,
steady lumbar
curvature
4 mos. Raises self from sitting position
with hips first
22 mos.
Turns over from lying
to supine position
4-6
mos.
Runs well without falling 2 yrs.

16.  RECEPTIVE LANGGUAGE
Understand few words 11 mos. Points to 5 body parts on
self or doll
1yr. 10
mos.
Points to 1 named body
part on request
1 yr. Follows 3-step command
given once
2 yrs.
Stops activity to name
objects
1 yr. Understands 200-400
words
2 yrs.
Stops activity to respond
to “no”
1 yr. Understand 800 words 3 yrs.
Points to familiar persons,
objects on request
1 yr. 3
mos.
Verbalizes past
experiences
3 yrs.
Follows one-step simple
command
1 yr. 3
mos.
Points to big, little soft,
loud
3 yrs.
Points to 3 named body
parts on request
1 yr. 5
mos.
Follows command with 2-3
actions
4 yrs.
Follows two-step
command
1 yr. 8
mos.
Understand app. 1500
words
4 yrs.
Points to 5-6 pictures of
common objects on
request
1 yr. 9
mos.

17.  EXPRESSIVE LANGUAGE
Says first word 10 mos. Uses plurals 2 yrs.
Shakes head and says “no-
no”
11 mos. Ask questions 2 yrs.
Imitates sounds of others
(‘mama”)
1 yr. Uses negative in speech 2.5
yrs.
Uses 3 words in speaking
vocabulary
13 mos. Enunciates vowel sounds 2.5
yrs.
Use of verbs appear 14 mos. Enunciate consonant sounds 3 yrs.
Uses at least six words 17 mos. Speech is about 75 to 80%
intelligible
3 yrs.
Refers to self by name 21 mos. Uses 3 to 4 syllable words 3 yrs.
Uses me and you 2 yrs. Says 6 to 8 word sentences 4 yrs.
Says 50 to 200 words 2 yrs. Speech is about 90 to 95%
intelligible
4 yrs.
Knows full name 2 yrs.

18.  EATING SKILLS
Sucks and swallows
liquids
Birth Holds cup with two hands 1 yr.
Gaging relax Birth Chews table food 1.3 yrs.
Sucks and swallows liquid
from spoon
2 mos. Grasps spoon & places in
mouth with some spilling
1.3 yrs.
Eats strained baby foods
from spoon
3 mos. Can manage spoon without
help with little spilling
1.5 yrs.
Brings hands against
bottle when eating
3 mos. Request for food when
hungry
1.11
yrs.
Sips from a cup that is held 4 mos. Request for liquid when
thirsty
1.11
yrs.
Gets excited at sound of
food preparation
4mos. Can hold small glass with
one hand without help
2 yrs.
Holds spoon with
assistance
5 mos. Can use fork to get food 3 yrs.

19.  DRESSING SKILLS
Pull and tug a clothes 3-4 mos. Attempts to place feet in
shoes
30
mos.
Remove shoes by self 1.2 yrs. Can choose own outfit 3 yrs.
Pull up pants 1.6 yrs. Can unbutton clothes 3 yrs.
Place socks on feet by self 1 mo. Places clothing on in correct
direction
3.6 yrs.
Can dress and undress with
supervision
4 yrs.
Can button front buttons on
clothing
4.8 yrs.
Can zip up and down/snap
simple snaps
5 yrs.
Can tie shoes with bows 5.6 yrs.

20.  GROOMING SKILLS
Cries when removed from
bathroom
5 mos. Can brush teeth with
assistance
3.6 yrs.
Splashes water with
hands and feet
6 mos. Can wash and dry face with
towel alone
4 yrs.
Grimaces when face is
washed with cloth
6 mos. Can brush teeth alone 4 yrs.
Exhibits resistance to
washing face
8 mos. Can put away toys with
supervision
4 yrs.
Can open and pull out
drawers
1.6 yrs. Can hung up clothes on
hook
4 yrs.
Can wash hands and face
but not well
2 yrs. Brushes hair alone 5 yrs.
Can wash front of body
while in bath
2 yrs. Hung up own clothes alone 5 yrs.
Can run a brush through
hair
2.5 yrs. Washes self alone 6 yrs.

21. TOILETING SKILLS
WHEN IS DEVELOPMENT DISABILITY PRESENT?
About 4 bowel movements a
day associated with waking
up
1mo. Climbs on to toilet by self 2.6 yrs.
2 bowel movements a day
either at waking up or after
being fed
2 mos. Can control for up to 5
hours
2.6 yrs.
Some delay shown between
feeding and elimination
4 mos. Begins to develop a routine
to elimination
3 yrs.
Stays dry for 1 to 2 hours
interval
7 mos. Attempts to wipe self but
fails
3.6 yrs.
May awaken at right & cry to
be changed
1.5 yrs. Stays dry at night 4 yrs.
May indicate wet pants 1.5 yrs. Can toilet self without
assistance
5 yrs.
Has only occasional
accidents
1.10
yrs.
Washes & dries own hands
after toileting
5 yrs.
Uses same words for both
functions of elimination
1.10
yrs.
One bowel movement a day 5 yrs.

22. THE HUMAN GENOME PROJECT (HGP)
was the international, collaborative research program whose goal was the
complete mapping and understanding of all the genes of human beings. All
our genes together are known as our "genome.“
GOALS OF THE HUMAN GENOME PROJECT (HGP)
1. Optimization of the data analysis.
2. Sequencing the entire genome.
3. Identification of the complete human genome.
4. Creating genome sequence databases to store the data.
5. Taking care of the legal, ethical and social issues that the project may pose.

28. EARLY DEVELOPMENT
Raymond's growth and development was observed to be different
from normal babies. He did not follow the normal course of psychomotor and
language development during the first two years, the milestones of which are
walking alone at one year or earlier, and ability to talk and express one's
thoughts in simple words or phrases at age two or a few months later. He first
sat with support and crawled when he was already two years old. He was
nonverbal and did not develop speech. The diagnosis showed that Raymond
has profound mental retardation. This means that he needs constant and high
intensity support all the time. He cannot manage himself independently even
in simple activities like daily living skills and would need help of professional
practitioners. Children with profound mental retardation score below 20 to 25
IQ points in a mental ability test.
BEHAVIOR AND PSYCHOSOCIAL DEVELOPMENT
At present, Raymond attends a private school for children with mental
retardation. It is his third year in special education. He has a good disposition
and displays a positive attitude towards the classroom tasks and activities. He
shows enthusiasm to learn and behaves well in circle time activities and
school programs with tolerable hyperactivity.

29. He wears a smile every time he comes to school. He greets the school
principal, teachers and classmates with a big smile, hug or he simply holds
their hands. There are days though when he shows slight tantrum and just lies
on the floor for some time. The teacher has you force him manually to get up
and do his lesson.
Raymond is able to pay attention every time his name called. He sits
independently during tabletop activities. He can help in class chores like
arranging the tables and chairs. He enjoys being with his teachers and
classmates, holds their hands, waves at them or does a "nose to nose kiss".
His attention span is growing longer especially when he plays with his favorite
colored 3D wooden blocks, or when watching a movie.
PSYCHOMOTOR SKILLS
With the help of the school's occupational therapist, he can now point
to his head, nose, eyes, mouth and hair with minimal to moderate assistance.
He can do the basic gross motor activities like walking with reduced
assistance, going up and down the stairs alone, following instructions to long
jump, crawl and engage in balance beam activities with minimal help. He can
grasp and transfer objects from one hand to other without dropping them. He
can scoop objects from one container to another by himself. He can sit for
longer hours with minimal distraction and can go through varied obstacle
courses that require the use of different parts of his body.

30. He can follow instructions to arrange the chairs with the teacher's verbal
cues and gesture.
He is able to do fine motor activities like tracing vertical and horizontal
lines with moderate physical assistance and verbal prompts. He can string 8
to 10 beads, insert pegs into the board and build a block tower with
minimum assistance.
COGNITIVE DEVELOPMENT AND COMMUNICATION SKILLS
When asked " Where is Raymond ?" he would look at himself in the
mirror and tap his image. He identifies objects and gives them to the teacher
when asked. He can repeat after the teacher the words "mama, papa ." He
can identify, discriminate and sort colors by pointing to them and group
them by himself. He can do simple figure insets (square, triangles and
circles) and complete simple puzzles. He can follow some instructions and
recognize common objects.
Books fascinate him to no end he loves to go over the pages of
encyclopedias. He would point to objects i. the book and ask the teacher to
name them by tapping her. Another activity that he likes to do is look at
cars passing by.

31. With the special education teacher's patient use of special
methods and behavior modification techniques, Raymond learned to
"say" good morning and good bye through gestures. He can now perform
cognitive task like puzzle formation, activities with knobbed cylinders and
beads, color sorting and transferring objects from one container to
another with minimal spillage. He can point to the parts of the body and
can write vertical and horizontal lines. He is still nonverbal and hardly
interacts with his classmates. The teacher is training him to express what
he wants by tapping the person's arm or shoulder.
QUANTITATIVE SKILLS
Raymond can identify the primary colors, sort and discriminate
them using the Lego and 3D colored wooden blocks with minimal verbal
cues. He can identify the primary shapes and insert them in the Tub 'O
Shape Box. He can identify some of the geometric shapes using the
geometric form insets.

32. DAILY LIVING SKILLS,PERSONAL MANAGEMENT AND PRE-VOCATIONAL
SKILLS
Raymond can remove and put on his clothes, slippers, shoes and
socks and fold garments .He can put on the ankle weights to strengthen
his lower extremities with or without or with minimal assistance. However,
he cannot tie his shoelaces yet.
In grooming, he can brush his teeth, apply powder, lotion and
cologne on his face and body with moderate verbal and physical prompts.
He can do the basic self-help activities like zipping up, buckling shoes,
grooming (brushing his teeth, powdering his body, combing his hair).
However, he is not yet toilet trained.
Raymond can do simple laundry (handkerchief and towel)with
maximum assistance. He can do some of the household activities like
washing the dishes (plastic or melamine plates, spoons, forks, glasses)
watering the plants, sweeping and mopping the floor and wiping the table
with moderate physical and verbal prompts. He can execute simple
cooking procedures like slicing ham or hotdog with a plastic knife, beating
an egg and scrambling it, with moderate to maximal assistance. He can
set the table and respond to simple step by step verbal direction like,
"please get the placemat, please get the plate, spoon, fork, glass, "He can
mop the floor and wipe the table with moderate assistance and verbal
prompts.

33. He can pour water into a glass alone, but he has to be
prompted verbally on when to stop or when to add some more water.
He shows enthusiasm in scooping elbow macaroni from one bowl to
another and pouring water from a pitcher to glasses with minimal
spillage.