TRISOMY 21 DOWN SYNDROME

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TRISOMY 21- DOWN SYNDROME

• Dr. Gupta
• PL-II

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Incidence

• Approximately one in 1000 live births.

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Genetics

• Trisomy 21 (47 21) - 94 The frequency of
  trisomy increases with increasing maternal age.
• Robertsonian translocation involving chromosome
  21- Approx. 3-4 not related to maternal age.
• Trisomy 21 mosaicism 2 to 3 cases

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Clinical Features

• Head and neck
• Brachycephaly
• Up-slanting palpebral fissures
• Epicanthal folds
• Brushfield spots
• Flat nasal bridge
• Folded or dysplastic ears
• Open mouth
• Protruding tongue
• Short neck
• Excessive skin at the nape of neck

• Extremities
• Short broad hands
• Short fifth finger
• Incurved fifth finger
• Transverse palmer crease
• Space between first and second toe
• Hyper flexibility of joints

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Neonatal features

• Flat facial profile
• Poor Moro reflex
• Excessive skin at the nape of neck
• Slanted palpebral fissures
• Hypotonia
• Hyper flexibility of joints

• Dysplasia of pelvis
• Anomalous ears
• Dysplasia of midphalanx of fifth finger
• Transverse palmer crease

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Mental Retardation

• Almost all DS babies have MR.
• Mildly to moderately retarded .
• Starts in the first year of life.
• Average age of sitting(11 mon) and walking (26
  mon) is twice the typical age.
• First words at 18 months.
• IQ declines through the first 10 years of age
  reaching a plateau in adolescence that continues
  into adulthood.

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Heart Disease

• 50 of Down Syndrome pts have heart disease
• Atrioventricular septal defect
• VSD
• Secundum ASD
• PDA
• Tetrology of Fallot
• Mitral valve prolapse
• AR MR

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GI abnormalities

• 5 of cases
• Duodenal atresia or stenosis sometimes assoc
  with annular pancreas in 2.5 of cases
• Imperforate anus
• Esophageal atresia with TE fistula is less common
• Hirschsprungs disease
• Strong assoc with celiac disease b/w 5 16
  5 16 fold increase as compared to general
  population

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Growth

• BW length and HC are less in DS
• Reduced growth rate
• Prevalence of obesity is greater in DS
• Weight is less than expected for length in
  infants with DS and then increases disproportion
  ally so that they are obese by age 3-4 yrs

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Eye problems

• Most common disorders are
• Refractory error 35 to 76 percent
• Strabismus 25 to 57 percent
• Nystagmus 18 to 22 percent
• Cataract occur in 5 of newborns.
• Frequency increases with age.

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Hearing loss

• Unilateral or bilateral
• Conductive sensorineural or mixed
• Otitis media is a frequent problem

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Hematologic disorders

• The risk of leukemia is 1 to 1.5 percent.
• 65 of newborn have polycythemia resulting in
  hypoglycemia.
• Risk of AML and ALL is also much higher than the
  general population.
• Transient leukemia exclusively affects NB.
• - It is asymptomatic with spontaneous
  resolution in 2-3 months.
• - Vesiculopustular skin eruptions are common
  and resolve with disorder.

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Endocrine disorder

• Thyroid disease Hypothyroidism occurs more
  frequently than hyperthyroidism.
• Diabetes The risk of type 1 diabetes is three
  times greater than that of the general population.

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Reproduction

• Women with DS are fertile and may become
  pregnant.
• Nearly all males with DS are infertile. The
  mechanism is impairment of spermatogenesis

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Atlantoaxial instability

• Excessive mobility of atlas (C1) and the axis
  (C2) may lead to subluxation of the cervical
  spine.
• Diagnosis made by lateral neck radiograph.
• Patients are advised to avoid contact sports.

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Sleep apnea

• Obstructive sleep apnea is more common.

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Skin disorder

• Palmoplantar hyperkeratosis
• Seborreic dermatitis
• Fissured tongue
• Cutis marmorata
• Geographical tongue
• Xerosis

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Diagnosis

• Prenatal screening
• If no screening It is recognized from the
  characteristic phenotypic features.
• Confirmed by Karyotype.

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Management

• 1. Growth Measurements should be plotted on the
  appropriate growth chart for children with DS.
• This will help in prevention of obesity and
  early diagnosis of celiac disease and
  hypothyroidism.
• 2. Cardiac disease All newborns should be
  evaluated by cardiac ECHO for CHD in consultation
  with pediatric cardiologist.
• 3. Hearing Screening to be done in the newborn
  period every 6 months until 3 yrs of age and
  then annually.

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Management (cont.)

• 4. Eye disorders - An eye exam should be
  performed in the newborn period or at least
  before 6 months of age to detect strabismus
  nystagmus and cataracts.
• 5. Thyroid Function Should be done in newborn
  period and should be repeated at six and 12
  months and then annually.
• 6. Celiac Disease Screening should begin at 2
  yrs. Repeat screening if signs/Sx develop.

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Management ( cont)

• Hematology CBC with differential at birth to
  evaluate for polycythemia as well as WBC.
• Atlanto-axial instability X ray for evidence of
  AAI or sub-luxation at 3 to 5 years of age.
• Alzheimers disease Adult with a Down Syndrome
  has earlier onset of symptoms. When diagnosis is
  considered thyroid disease and possible
  depression should be excluded.

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Mortality
Median age of death has increased from 25 yrs in
1983 to 49 yrs in 1997 an average of 1.7 yrs
increase per year. Most likely cause of death
is CHD Dementia Hypothyroidism and
Leukemia. Improved survival is because of
increased placements of infants in homes
and changes in treatment for common causes of
death. Survival is better for males and blacks.
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Counseling

• May begin when a prenatal diagnosis is made.
• Discuss the wide range of variability in
  manifestation and prognosis.
• Medical and educational treatments and
  interventions should be discussed.
• Initial referrals for early intervention
  informative publications parent groups and
  advocacy groups.

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