Post on 22-Dec-2015
transcript
Background
In 1866, Down described the clinical characteristics we know now as Down Syndrome
In 1959, Lejeune and Jacobs independently discovered trisomy 21 to be the cause
Most common and well known chromosomal abnormality
Most common cause of intellectual disability
Description
Down Syndrome is characterized by mental retardation, dysmorphic facial features, and distinctive phenotypic traits
Classically, hypotonia, flat facies, upslanting pqlpepral fissures, and small ears
Children with Down Syndrome have such a typical look that they look more like each other than their families
Associated Abnormalities: Cardiac Congential heart disease (40-50%, most
not symptomatic at birth) AV canal (60%) VSD ASD PDA Tetralogy of Fallot Aberrant subclavian artery
Associated Abnormalities
Hearing loss (66-75%) Strabismus (33-45%) Nystagmus (15-35%) Refractive errors (50%) Nasolacrimal duct stenosis Delayed tooth eruption
Associated Abnormalities: GI Tracheoesophageal fistula GI atresia (12%) Celiac disease Meckel diverticulum Hirschsprung disease (1%) Imperforate anus
Associated Abnormalities
Renal malformations Hypospadias Cryptorchidism (5-50%) Thyroid disease (15%): congenital
hypothyroidism Neonatal polycythemia Leukemia (1%, 10-30x greater risk than
general population) Retinoblastoma and germ cell tumors
Associated Abnormalities
Obesity Alopecia areata (10-15%) Seizures (5-10%) Alzheimer disease (nearly all over 40
years) Mild to moderate mental retardation (IQ
range 25-70)
Complications
Otitis media with effusion (50-70%) Sinusitis Tonsillar hypertrophy, leading to OSA
(33-75%) Obstructive bowel disease Constipation
Complications
Subluxation of hips Atlantoaxial instability (10-20%, secondary to ligamentous laxity)
Epidemiology
Male > female (1.3:1) 75% of concepti with trisomy 21die in
embryonic or fetal life 85% survive past one year of age Over 50% are expected to live longer
than 50 years Congenital heart disease is most
important factor in determining survival
Frequency
In the United States, frequency is about 1 in 800births Each year, approximately6000 children born with Down Syndrome
Etiology
Full Trisomy 21 (94%) Most common error is maternal
nondisjunction (failure to segregate) at the first meiotic division
Mosaicism ( 2.4%): 2 cell lines present, less severe
Translocation ( 3.3%): 50% de novo, 50% balanced translocation from one parent
Etiology
Advanced maternal age is risk factor for maternal meiotic nondusjunction
At 35 years, risk is 1 in 385 At 40 years, risk is 1 in 106 At 45 years, risk is 1 in 30
Diagnosis
Clinical diagnosis with classic constellation of dysmorphic features
History and physical!
Confirm with karyotype
History
Previous history of infant with Down syndrome in the family
Parental concern about hearing, vision Feeding history: adaquate calories,
vomiting Stooling pattern
History
Development: delay in cognitive abilities, motor or language development, social competence
Cardiac history:fainting episodes, palpitations
Symptoms of sleep apnea: snoring, daytime somnolence, behavioral changes, and school problems
History
Symptoms of atlantoaxial instability: easy fatigability neck pain, limited neck mobility or head
tilt, torticollis difficulty walking, change in gait pattern loss of motor skills, incoordination sensory deficits spasticity, hyperreflexia
Physical
General-Short stature-Hypotonia (80-100%), with open mouth and protruding tongue-Midface hypoplasia
Physical
Head-Brachycephaly with flattened occiput-Microcephaly Eyes-Upslanting palpepral fissures (98%)-Inner epicanthal folds-Brushfield spots (speckled iris)
Physical
Ears-Small, prominent, low set, overfolding of
helix, small canals Nose-Small (85%), flat nasal bridge
Physical
Tongue-Relative but not true macroglossia Mouth-High arched palate Teeth-Missing (50%)-Small, hypoplastic
Physical
Heart-Assess for murmur, arrthymia Abdomen-Look for distension in neonate (rule out
obstruction)-Diastasis recti GU-In males, small penis and cryptorchidism
Physical
Extremities-Broad hands, with short metacarpals-Single transverse palmar crease (50%)-5th finger with hypoplasia of midphalanx
and clinodactyly (60%)-Wide gap between 1st and 2nd toes-Hyperflexibility of joints Skin-Fine, soft, sparse hair
Next steps
Genetic counseling recommended History of Down Syndrome increased risk
of recurrence (1%) Affected individuals rarely reproduce Only 15-30% females are fertile Males are infertile
Monitoring
Routine vaccinations Medications Growth and development:-Specific growth charts available-Average age of meeting developmental
milestones differs from general population
Monitoring
Cardiac-Early evaluation and follow-up for
congenital heart disease-Endocarditis prophylaxis for certain
lesions Endocrine-Thyroid function tests as newborn to rule
out hypothryoidism, with follow-up
Monitoring
Ophthalmologic-Early evaluation for cataracts and
glaucoma Ear, nose, throat-Periodic audiologic exams Orthopedic-Screen for atlantoaxial instability with
radiography
Monitoring
Psychiatric/Social:-Screen for depression or anxiety-Manage behavioral problems-Social support-Family support-Long term living arrangements