This document discusses the causes and classifications of developmental disabilities. It identifies several potential causes including congenital issues present at birth, genetic disorders, metabolic disorders, prenatal infections, complications during birth, and environmental factors like poverty and toxins. Specific disorders mentioned include Down syndrome, Fragile X syndrome, PKU, cystic fibrosis, and cerebral palsy. Developmental disabilities are classified based on factors like intellectual ability, specific learning disabilities, speech/language delays, emotional/behavioral disorders, sensory impairments, and autism.

1. DEVELOPMENTAL
DISABILITIES: CAUSES
AND CLASSIFICATIONS
Chapter 5 – The exceptional Child – Inclusion in early childhood
education; allen, K. eileen and Cowdery, Glynnis E.; 2012

2. Causes of Developmental Disabilities
• Congenital – a problem present at birth
• Nature and nurture – work together to “determine developmental
outcomes”
• Check out the prenatal developmental chart on p. 101 in your text!
• Biological insult – may or may not cause a developmental problem
• Genetic disorders – are present at birth, but are not necessarily
hereditary
• Most single-gene disorders – both parents are healthy carriers of an
abnormal gene. Each pregnancy has a 25% potential outcome of the
child having the disorder

3. Syndromes
• Down Syndrome – Trisomy 21; probably the most well-known cause
of intellectual disabilities
• Common characteristics described on p. 103
• Many children with Down syndrome also have health issues such as heart
defects
• Fragile X syndrome- like Down syndrome, a chromosomal
abnormality.
• The most common inherited cause of intellectual disabilities in the U.S.
• More likely to impact boys more severely

4. Metabolic and Gene Disorders
• PKU – phenylketonuria
• Every newborn in the U.S. is screened with a simple blood test following birth
• Dietary changes can prevent irreversible brain damage
• Tay Sachs – most likely to occur in people of Eastern European Jewish
descent
• Cystic Fibrosis – fatal physical disorder that does not interfere with mental
development; children are now living into adulthood with this disease
• Sickle-cell anemia – serious health disorder that primarily affects AfricanAmerican
• Duchenne Muscular Dystrophy – fatal muscular disease that occurs in
males

5. Prenatal Infections and Intoxicants
• Many are listed in your text on p. 105
• Better prenatal care has improved outcomes in recent years, but
pregnancy is not without its risks
• FAE and FAS – the #1 preventable cause of intellectual disabilities
• Poor nutrition – sadly, this is still an issue with pregnant women,
particularly teenage mothers.

6. Other Complications
• Birth – CP (cerebral palsy) may result from lack of oxygen during birth
• Post-natal diseases and illnesses
• Lead poisoning – still a huge problem, particularly in high poverty
areas
• Poverty – increased risk factors including
•
•
•
•
•
Nutritional deficiency
Lack of good healthcare and education
Homelessness
Single parent families
Lack of quality childcare – may even be detrimental to child’s development

7. Classifications of Developmental
Disabilities
• SLD – specific learning disabilities – categorized by normal or above
normal IQ, but discrepancies in ability to read, write, or do math as
compared to IQ
• Speech and language problems – may or may not accompany other
developmental disorders
• Intellectual disabilities (mental retardation) – MR is now considered a
more offensive term
• Emotional disorders (ED or BED) – behavior or emotional responses
are not age or developmentally typical and interfere with normal
functioning in education, social, or vocational settings

8. Classifications of Developmental
Disabilities (cont.)
• Multiple disabilities – more than one disability
• Hearing loss – “deafness” or “hard of hearing”
• Orthopedic impairments – may include congenital impairments such
as absence of a limb or paralysis; impairments caused by diseases
such as polio; neurological or spinal cord damage causing problems
such as paralysis as in spina bifida; impairments caused by injury or
other causes
• Health impairments – heart, cancers, chronic diseases
(asthma, diabetes, CF), etc.

9. Classifications of Developmental
Disabilities (cont.)
• Visual impairments – blind; partially sighted
• Deaf/blind – multisensory disorder
• Autism – a developmental disorder of the brain that is behaviorally
defined along a spectrum. Some cognitive delay is present in about ¾
of the children with autism
• TBI – Traumatic brain injury