Down Syndrome: Causes, Features and History

• Down Syndrome, also known as Trisomy 21, is a genetic condition caused by an extra copy of chromosome 21.
• It can lead to mental and physical challenges
• A wide range of abilities can be observed among children with Down Syndrome.

Historical Background

• It has been identified as one of the first symptom complexes associated with intellectual disability.
• 1866: Dr. John Langdon Down provided the first physical description of Down Syndrome.
• 1959: The underlying chromosomal abnormality was identified as an additional chromosome 21.
• 2000: An international group of scientists completed the genomic sequence of the long arm of chromosome 21.

Physical Features of Down Syndrome:

• A flattened face, especially the bridge of the nose
• Almond-shaped eyes that slant upwards
• Short neck
• Small ears
• A tongue that tends to stick out of the mouth
• Tiny white spots on the iris (colored part) of the eye
• Small hands and feet
• A single line across the palm of the hand (palmar crease)
• Small pinky fingers that sometimes curve toward the thumb
• Poor muscle tone or loose joints
• Shorter than average height as children and adults

Associated Medical Complications:

• Congenital heart defects
• Sensory impairments, affecting vision and hearing
• Endocrine abnormalities, including hypothyroidism and diabetes
• Short stature and obesity problems
• Orthopedic problems, such as neck subluxation
• Dental problems, including gum disease, small and malformed teeth
• Gastrointestinal, renal, and urinary tract anomalies/problems
• Epilepsy
• Hematologic disorders like leukemia and low iron/anemia
• Skin conditions such as vitiligo and alopecia

Neurodevelopment and Behavior:

• Delayed Development
• Language development is delayed
• Gross motor skill development is delayed
• Their cognitive abilities typically place them in the mildly-to-moderately low IQ range.
• There is an increased risk of behavioral, emotional, and psychiatric issues.
• Other diagnoses and comorbidities for children with Down Syndrome can include ADHD and autism spectrum disorder.
• Neuropathology of Alzheimer's can appear at age 45.
• 75% meet criteria for dementia by age 65.

Prevalence, Causes, and Risk Factors:

• Down Syndrome occurs in approximately 1 in 700 live births.
• Is caused by an extra chromosome, but the exact reasons for its occurrence are still not fully understood.
• Maternal age is a known risk, with women who are 35 years or older being more likely to have a pregnancy affected by Down Syndrome.

Diagnosis of Down Syndrome:

• Screening tests can help assess if a pregnancy has a lower or higher chance of resulting in Down syndrome
• Screening tests cannot provide an absolute diagnosis, but they are safer for both the mother and the developing baby
• Diagnostic tests are capable of detecting whether a baby will have Down syndrome, but are riskier
• Neither screening nor diagnostic tests can predict the full impact of Down syndrome on a baby.

Screening Tests

• Screening tests combine a blood test to measure substances in the mother's blood and an ultrasound creating an image of the baby
• The technicians look for fluid behind the baby's neck in the ultrasound
• Determines the baby's risk for down syndrome and can produce abnormal results

Diagnostic Tests

• Often performed after a screening test indicates potential issues
• Chorionic villus sampling (CVS) examines material from the placenta.
• Amniocentesis examines the amniotic fluid surrounding the baby.
• Percutaneous umbilical blood sampling (PUBS) examines blood from the umbilical cord.

Medical Evaluation for Children with Down Syndrome:

• Evaluation: congenital heart disease, vision, hearing
• Ongoing monitoring: hemoglobin, thyroid stimulating hormone (TSH), obesity, hearing, vision, dental
• Evaluation with symptoms: neck subluxation, swallowing and choking with feeding, sleep apnea, celiac disease
• Vigilance: renal problems, leukemia, diabetes, seizures, rheumatoid arthritis, testicular cancer

Developmental Milestone Expectations:

• Typically reach their developmental milestones 1.5 to 2 times later than other children.

Cognitive Deficits and Neurological Complications:

• The relationship between the genetic effects of the trisomy that causes DS and the pathogenetic mechanisms that underly cognitive deficits are not fully understood
• Observed structural changes in the brain do not seem to affect all individuals in the same way
• Stress, infection, drug side-effects, access to early intervention, and medical problems (e.g., seizures) can influence cognitive outcomes
• Difficulties with memory throughout the lifespan

Assessment and Support for Down Syndrome:

• Down Syndrome is a life long condition
• Early intervention services can improve physical and intellectual abilities.
• Services include speech, occupational, and physical therapy.
• Children may need additional support or attention in school.

Education Considerations:

• Assessments can identify a child's strengths and difficulties in an educational setting.
• Research supports mainstream education to improve language and academic skills.
• Promoting social inclusion and using effective instruction methods are essential.
• Ensuring access to opportunities for academic instruction

Intervention Considerations:

• Provide parents with information and education on the condition.
• Support Through: support groups and respite care
• IEP: based on educational strengths and needs
• Use of visual aids, vision and hearing supports if needed
• Medical regimens are accommodated in schools

Outcomes for Individuals with Down Syndrome:

• There has been significant improvement since the 1970s.
• Parent advocacy groups have formed
• There is a trend toward inclusion.
• Increased life expectancy to 60 years
• Supported employment benefits
• Medical complications
• Bullying, ostracism
• Lack of certain adult milestones (e.g., driver's license)
• Lack of adequate services and supports in adulthood

Down Syndrome, or Trisomy 21, is a genetic disorder resulting from an extra copy of chromosome 21, leading to physical and mental challenges. Identified in 1866 by Dr. John Langdon Down, the chromosomal abnormality was discovered in 1959. Key features include a flattened face, upward slanting eyes, and small hands.