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DOWN SYNDROME UPDATE 2007

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Prenatal Screening for Down Syndrome. What's all the talk about? ... Brothers and Sisters of Persons with Down Syndrome. Brothers and sisters... – PowerPoint PPT presentation

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Title: DOWN SYNDROME UPDATE 2007


1
DOWN SYNDROME UPDATE2007
  • Tamison Jewett, MD
  • Wake Forest University Health Sciences

2
Down syndrome
  • occurs in 1650 live births
  • The underlying causes
  • 94 due to nondisjunction (unequal cell division)
    resulting in 47 chromosomes
  • 3.3 due to an unbalanced translocation
  • 2.4 are mosaic (46/47)
  • critical region

3
Down syndrome--History
  • First described by Dr. John Langdon Down in
    England in 1866
  • In 1956, scientists discovered that the typical
    human cell has 46 chromosomes
  • In 1958, Lejeune discovered that the cells from
    an individual with DS had an extra chromosome 21
  • In 1959, 9 people with DS were found to have an
    extra chromosome 21

4
  • Abnormal cell division leading to abnormal
    chromosome distribution can occur in EITHER
    PARENT. As women age, our risk for this to occur
    increases, as follows
  • Maternal Age Incidence of DS at delivery
  • 15-29 1 in 1500
  • 30-34 1 in 800
  • 35-39 1 in 270
  • 40-44 1 in 100
  • 45 and over 1 in 50

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p-arm

q-arm
autosomes

NOR, acrocentic
Sex chromosomes
Ideogram of the human chromosomes
8
Syndrome
  • a recognizable pattern of features, usually
    owing to a specific cause., e.g., Down syndrome,
    wherein the cause is extra chromosome 21 material

9
Down syndrome--features
  • Brachycephaly
  • Excess nuchal skin
  • Hypoplastic midface
  • Upslanting palpebral fissures
  • Small ears w/ overfolded helices
  • 5th finger clinodactyly
  • Wide gap between 1st and 2nd toes
  • Single transverse palmar crease(s)(40)
  • Heart defect in 40
  • Fine, soft hair

10
  • It is important to remember that individuals with
    DS look mainly like their families it is the
    characteristic pattern of features that causes
    them to resemble one another.

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13
Robertsonian Translocations
Can result in Down syndrome
14
p-arm

q-arm
autosomes

NOR, acrocentic
Sex chromosomes
Ideogram of the human chromosomes
15
Current dilemmas in clinical care for persons
with DS
  • Celiac disease
  • Thyroid disorders
  • Atlantoaxial instability

16
Celiac disease (CD)
  • Autoimmune disorder caused when the body reacts
    to gluten, the protein in barley, wheat, and rye
  • Damage occurs to the absorbing surface of the
    small intestine
  • Ongoing damage results in reduced absorption of
    nutrients and in diarrhea/constipation, bloating,
    and poor growth

17
Celiac disease
  • Can show itself after only 6 months of exposure
    to gluten
  • May not appear until late childhood or adulthood
  • May not be associated with classic symptoms
    above
  • Can be screened for with blood tests

18
Recommended blood tests to screen for celiac
disease
  • Serum IgA
  • Serum IgA tissue transglutaminase (tTG)

19
Celiac disease
  • Diagnosis is confirmed by intestinal biopsy
  • Treatment is the removal of gluten from the diet

20
Celiac disease prevalence
  • 1133 individuals in the general population
  • Is higher in individuals with type 1 diabetes
    (childhood onset), some immune disorders, and
    Turner, Williams, and Down syndromes
  • Is reported to occur in 5-17 of individuals with
    DS

21
Celiac disease
  • Can be difficult to diagnose in the general
    population due variability of symptoms
  • In individuals with DS, symptoms may be
    attributed to DS rather than to CD these include
  • Growth failure
  • Recurrent abdominal pain
  • Constipation
  • Irritability
  • Behavior changes

22
Celiac disease
  • In one study of DS individuals with CD,
  • 69 had classical symptoms (diarrhea, failure to
    thrive)
  • 11 had atypical symptoms (such as behavior
    changes, irritability)
  • 20 had silent disease (minimal, if any,
    nonspecific symptoms)
  • There does not appear to be any negative effect
    from this on people with DS

23
Celiac disease
  • People with type 1 diabetes and with autoimmune
    thyroid disease are at increased risk for CD
  • People with DS are at increased risk for type 1
    diabetes and for autoimmune thyroid disease
    further evidence for increased risk for CD in
    Down syndrome

24
Unresolved issues regarding celiac disease for
individuals with DS
  • When to screen?
  • Some say 2 years old some say 3 there is no
    consensus
  • Is there a need to re-screen?
  • It is documented that some individuals who are
    initially screen-negative will later become
    positive and have CD
  • No re-screening protocol is agreed upon at this
    time
  • Any person who develops symptoms of CD after
    having been negative should be considered for
    re-screening
  • What is the prevalence of CD in adults with DS?
  • We dont know

25
Thyroid disorders in DS
  • Occur in 15 of individuals with DS (there is a
    3-54 prevalence among studies)
  • Symptoms of hypothyroidism (increase in weight
    with reduced height velocity, dry skin,
    constipation) overlap with features of DS
  • While decreased thyroid function is most common,
    increased function is also described in DS

26
Thyroid disorders detection
  • Newborn screening
  • Congenital hypothyroidism occurs more commonly in
    DS
  • Blood testing after the newborn period (one month
    onward)
  • Thyroxine (T4) and thyroid stimulating hormone
    (TSH) levels should be performed at 6 months, 1
    year, and every year thereafter
  • Autoimmune thyroiditis is detected by measuring
    thyroid antibodies in addition to the above

27
Thyroid disorders treatment
  • When T4 is low and TSH is high and antithyroid
    antibodies are normal, this is primary
    hypothyroidism
  • When T4 is low and TSH is high, and antithyroid
    antibodies are present, this is secondary
    hypothyroidism
  • Hypothyroidism is treated with thyroid hormone
    replacement thyroxine

28
Thyroid disorders treatment
  • When T4 is high, there is hyperthyroidism
  • Symptoms of hyperthyroidism include rapid heart
    rate, weight loss or poor weight gain, and
    irritability
  • Management usually involves treatment with
    anti-thyroid drugs later followed by thyroid
    ablation with radioactive iodine followed by
    thyroid hormone replacement

29
Thyroid disorders concerns
  • Studies show that many physicians do not screen
    their patients as recommended
  • Further studies should be done to determine
    whether individuals with DS are being treated
    adequately once thyroid dysfunction is discovered

30
Thyroid disorders
  • For the present, current screening
    recommendations should continue

31
Atlanto-axial instability (AAI)
  • Is defined as a measurement of greater than 5mm
    and up to 7mm between the posterior portion of
    the first cervical vertebra (C1) and the anterior
    portion of the second cervical vertebra (C2) as
    measured by xrays of the neck in flexion,
    neutral, and extension
  • Measurements of more than 7mm are markedly
    abnormal, and MRI is warranted

32
Atlantoaxial instability (AAI)
  • 15 of individuals with DS who are less than 21
    yo have laxity of the atlantoaxial joint
    measurement of 5-7mm)
  • Most are asymptomatic
  • 10 (2 of all with DS in this age group)
    develop spinal cord compression

33
Atlantoaxial instability
  • Xray screening for AAI was initially recommended
    in 1983 for athletes wishing to participate in
    Special Olympics
  • Later, this recommendation was adopted for a
    number of health supervision protocols for
    persons with DS

34
Atlantoaxial instability
  • There is debate about whether screening is
    necessary for all DS individuals because
  • Measurements are sometimes inaccurate
  • Persons with AAI are not necessarily at risk for
    spinal cord injury
  • Abnormal measurements may actually return to
    normal in future
  • People with normal measurements early on may have
    abnormal measurements later
  • Most people with spinal cord injuries do not
    sustain them during athletic activity

35
Atlantoaxial instability
  • The Down Syndome Medical Interest Group (DSMIG)
    of the UK no longer recommends routine screening
  • Doctors are reminded to be aware of
    signs/symptoms of spinal cord compression (neck
    pain, head tilt, change in gait, change in
    bowel/bladder function, etc.) and to act
    accordingly
  • The DSMIG of the US continues to recommend
    routine screening at 3-5 yrs. of age

36
Atlantoaxial instability recommendations for
future
  • Physicians caring for individuals with DS must
    remain alert to signs/symptoms of spinal cord
    compression despite a history of normal screening
    neck xrays
  • Be aware that the risk for neck injury is greater
    during surgical neck manipulation (for
    anesthesia) than for athletic participation BUT
    IS STILL LOW
  • Current recommendation should be continued for
    now (until more data available), with the
    addition of neural canal width measurements on
    xrays taken

37
Atlantoaxial instability future directions
  • A multidisciplinary group of neurologists,
    neurosurgeons, radiologists, etc. should perform
    a large study to determine if there is a more
    sensitive method to screen for AAI in people with
    DS

38
Prenatal Screening for Down Syndrome
39
Whats all the talk about?
  • This month (January 07), the American College of
    Obstetrics and Gynecology (ACOG) has issued new
    practice guidelines for the screening of
    pregnancies for DS and other aneuploidies (extra
    chromosome conditions).

40
Historically
  • Maternal age of 35 at the time of delivery has
    been used to identify women at greatest risk for
    having a child with DS and other aneuploidies
  • This is the age at which a womans risk to have a
    child with DS equals her risk to have
    complication(s) from amniocentesis

41
Historically
  • In the 80s and 90s, biochemical markers (AFP,
    hCG, and uE3) were identified that could be
    measured in a pregnant womans blood, which
    increased our ability to detect fetuses at
    increased risk for DS
  • Still, 30 of affected babies were missed

42
Historically
  • In the mid-90s, researchers found an association
    between the size of a fluid collection at the
    back of the fetal neck in the first trimester
    detected on ultrasound called nuchal
    translucency (NT) and the risk for DS as well as
    a number of other conditions
  • Guidelines for the measurement of NT have since
    been established

43
Then
  • We learned that the NT measurement combined with
    measures of maternal serum free-beta hCG and
    pregnancy-associated protein A (PAPP-A) in the
    first trimester can increase the detection rate
    of DS, and when used in conjunction with second
    trimester screening, can increase detection to
    95.
  • this assumes a 5 false positive rate

44
So, whats the new recommendation?
  • Screening and subsequent diagnostic testing (such
    as amniocentesis), if indicated, should be
    available to all women who present for prenatal
    care before 20 weeks gestation regardless of
    maternal age.
  • Women should be counseled regarding their options
    as well as the differences between screening and
    diagnostic testing.

45
Brothers and Sisters of Persons with Down Syndrome
46
Brothers and sisters
  • Current research supports that brothers and
    sisters of children with DS are more likely to be
    positively impacted by their DS sibling than
    adversely so.
  • Sibs of DS children tend to show more kindness
    and compassion.
  • Parents of DS siblings report more warmth and
    less conflict among their children than parents
    in control families.

47
Brothers and sisters of children with DS
  • Are not more prone to behavioral problems than
    other children, as was previously thought
  • Assume more caregiving activities than other
    children
  • Brothers assume as much responsibility as sisters

48
Brothers-and-Sisters Workshops
  • The National Down Syndrome Societys national
    conference and the National Down Syndrome
    Congress meetings as well as other settings have
    provided researchers with information about how
    DS siblings are faring.
  • More than 3, 380 DS brothers and sisters have
    participated.

49
Common questions from DS brothers and sisters
  • Medical
  • How long will he/she live?
  • Why are some people with DS short?
  • Why does my brother/sister have DS/
  • How do they get the extra chromosome?
  • Why does his/her face look different?
  • Why cant he/she walk very well?
  • Are all kids with DS strong?

50
Common questions (cont.)
  • Social
  • Can people with DS have normal jobs?
  • How are people with DS different from people who
    dont have it?
  • Will he/she be different?
  • Will he/she be ugly?
  • My brother/sister knows that he/she has DS and is
    different does yours?

51
Common questions (cont.)
  • Education
  • Does my sibling have to go to a special school?
  • Can people with DS graduate from college?
  • Does it take them longer to learn things?
  • Why did he/she do preschool twice?
  • How do they think?

52
Common questions (cont.)
  • History
  • Why is it called DS?
  • Who was the first person in history to have DS?
  • Why did people in the old days call kids with DS
    M----?

53
What has been learned?
  • When a sibling questions their parent(s) about
    DS, he/she has been thinking about the issue well
    beforehand.
  • A running dialogue about DS is helpful.
  • Parents should consider periodically asking
    siblings if they have questions about DS.
  • Researching questions together can be an enabling
    discovery process.
  • Allow siblings to express their negative
    feelings they are typically temporary.

54
What has been learned?
  • Recognize the siblings difficult moments, e.g.,
    someone picking on their DS sibling or asking
    them why their brother/sister looks different.
  • Limit caregiving responsibilities
  • although most siblings enjoy these to some
    extent, they should not be counted on to be the
    caregiver and need their own space

55
Parents should strive to
  • Recognize the individuality and uniqueness of
    each child in the family
  • Be fair
  • Take advantage of support opportunities for
    siblings
  • Many comment on the benefits of meeting other
    siblings of DS children
  • Seek support opportunities for themselves

56
Conclusions
  • Persons with DS add an appreciated dimension to
    their families and deepen their siblings (and
    parents) understanding of humanity.
  • Siblings of children with DS often have a deeper
    respect for diversity.
  • Siblings typically recognize that happiness is
    not defined by material possessions, accolades,
    or fame.

57
My conclusion
  • Everyone could benefit from having a child with
    Down syndrome in their family!

58
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