Psychosis due to genetics Presented by: Agbisit, Queenie Balao,
Sylvester Barrameda, Yasmin Beguia, Andriza Mae Biliran, Joyce
Venus Bognot, Mary Astrid Bueno, Chrisnabelle-Liza Calamigan,
Scheibel Kates Calbay, Hazel Ellenore Calingasan, Cristine Castro,
Lou Sandino Corpuz, Grace
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Down Syndrome ( Trisomy 21 ) is a chromosomal abnormality
characterized by the presence of an extra genetic material on the
21 st chromosome which causes delays in the way a child develop,
both physically and mentally. it is the most common of the
chromosomal disorders and is the major cause of mental retardation.
it is named after John Langdon Down, the British doctor who
described the syndrome in 1866.
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What causes it? In most cases of down syndrome a child gets an
extra chromosome 21 for a total of 47 chromosome instead of 46.
Women at age 35 and older have a significant higher risk of having
a child with the condition. Down syndrome occurs in 1 in 800
births.
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Karyotype of Trisomy 21
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People with Down Syndrome tend to show certain physical factors
such as: a. Flat facial profile b. Oblique eye fissures with
epicanthic folds on the inner corner of the eye c. White spots on
the iris ( Brushfield spots ) d. Abnormally shaped ears e.
Protruding tongue f. Single palmar transversal crease g. Muscle
hypotonia h. Small hands and feet
Slide 6
Mental retardation is the overriding feature of Downs syndrome.
Most people with Downs syndrome have IQs that fall in the mild to
moderate range of mental retardation. Approximately 80% of those
afflicted have an IQ of 25 to 50. They may have delayed language
development and slow motor development.
Slide 7
Patients with Downs syndrome are placid, cheerful and
cooperative which facilitates their adjustment at home. However,
those seems to change in adolescents, especially those in
institutions, who may develop various emotional difficulties,
behavior disorders, and ( rarely ) psychotic illness.
Slide 8
There are a variety of other health conditions that are often
seen in people who have Down syndrome, including: a. congenital
heart disease b. hearing problems c. atresias of the esophagus and
small bowel d. neuropathologic changes characteristic of Alzheimers
disease. ( patients older than 40 ) e. abnormal immune responses
that predispose them to serious infections, particularly of the
lungs and to thyroid autoimmunity.
Slide 9
With the advent of antibiotics few young patients succumb to
infections, but most of them do not live beyond the age of 40.
Despite all these problems, improved medical care has increased the
longevity of individuals with trisomy 21. No treatment has proved
effective.
Slide 10
Prader-Willi Prader-Willi syndrome is an autosomal dominant
disorder characterized by mild to moderate mental retardation or
learning problems, short stature, hypotonia, obesity, small hands
and feet, and hypogonadism. In 65% to 70% of cases, an interstitial
deletion of band q12 in the long arm of chromosome 15,
del(15)(q11.2q13), can be detected. in all cases the deletion
affects the paternally-derived chromosome 15
Slide 11
Children with the syndrome may also have behavior problems such
as obsession, compulsion, stubbornness, and temper tantrums. occurs
in approximately one of every 12,000- 15,000 people, in both boys
and girls
Slide 12
Angelman syndrome Patients with the phenotypically distinct
Angelman syndrome are born with a deletion of the same chromosomal
region as Prader-Willi but derived it from their mothers. Patients
are also mentally retarded, but in addition they present with
ataxic gait, seizures, and inappropriate laughter and excitability.
Because of their laughter and ataxia, they are also called "happy
puppets.".
Slide 13
Mental retardation is first noted at around six months of age;
however, the unique clinical features of AS do not manifest until
after one year of age, and it can take several years before the
correct clinical diagnosis is obvious.
Slide 14
Cri du chat syndrome also known as chromosome 5p deletion
syndrome, 5p minus syndrome or Lejeunes syndrome is a rare genetic
disorder due to a missing part of chromosome 5. French term
(cat-cry or call of the cat) referring to the characteristic
cat-like cry of affected children.
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first described by Jrme Lejeune in 1963 affects an estimated 1
in 20,000 to 50,000 live births, strikes all ethnicities, and is
more common in females by a 4:3 ratio.
Slide 18
Signs & Symptoms The syndrome gets its name from the
characteristic cry of affected infants, which is similar to that of
a meowing kitten, due to problems with the larynx and nervous
system. About 1/3 of children lose the cry by age 2. Other
symptoms: feeding problems because of difficulty swallowing and
sucking. Low birth weight and poor growth.
Slide 19
behavioral problems such as hyperactivity, aggression,
tantrums, and repetitive movements. unusual facial features which
may change over time. excessive dribbling constipation.
Slide 20
Other common findings: hypotonia, microcephaly, growth
retardation, a round face with full cheeks, hypertelorism,
epicanthal folds, down-slanting palpebral fissures, strabismus,
flat nasal bridge, down- turned mouth, micrognathia, low-set ears,
short fingers, single palmar creases and cardiac defects (eg. VSD,
ASD, PDA,TOF). People with Cri du chat are fertile and can
reproduce.
Slide 21
Late childhood and adolescent findings: significant
intellectual disability, microcephaly, coarsening of facial
features, prominent supraorbital ridges, deep-set eyes, hypoplastic
nasal bridge, severe malocclusion, and scoliosis. Affected females
reach puberty, develop secondary sex characteristics, and
menstruate at the usual time. The genital tract is usually normal
in females except for a report of a bicornuate uterus. In males,
testes are often small, but spermatogenesis is thought to be
normal.
Slide 22
Genetics due to a partial deletion of the short arm of
chromosome number 5, also called "5p monosomy". 90% of cases
results from a sporadic, or randomly- occurring, de novo deletion.
10-15% are due to unequal segregation of a parental balanced
translocation where the 5p monosomy is often accompanied by a
trisomic portion of the genome.
Slide 23
Loss of a small region in band 5p15.2 (cri du chat critical
region) correlates with all the clinical features of the syndrome
with the exception of the catlike cry band 5p15.3 (catlike critical
region) 2 noncontiguous critical regions contain genes involved in
this condition's etiology Semaphorine F (SEMA5A) and Delta catenin
(CTNND2) are potentially involved in cerebral development.
telomerase reverse transcriptase(hTERT ) gene ( 5p15.33) may
contribute to the phenotypic changes in cri du chat syndrome as
well.
Slide 24
Common Behavioural Difficulties Concentration difficulties and
hyperactivity. Self-injurious and compulsive behaviour:
self-biting, skin picking, hitting head with hand, and hitting head
against objects. Three main theories 1. Neurotransmitters
(dopamine, serotonin and the endorphins) 2. Response to pain and
discomfort 3. Learned behaviour Stereotyped behaviour
Slide 25
Fragile X syndrome Is the prototype of diseases in which the
mutation is characterized by a long repeating sequence of three
nucleotides, in most cases the affected sequences share the
nucleotides guanine and cytosine. With a frequency of 1 in 1500 for
affected males and 1 in 8000 for affected females, fragile-X
syndrome is the second most common genetic cause of mental
retardation, after Down syndrome. It is an X-linked disorder
characterized by an inducible cytogenetic abnormality in the X
chromosome and an unusual mutation within the familial mental
retardation 1 (FMR1) gene. The fragile site on the X chromosome is
expressed when cells are cultured in a folate-poor medium.
Slide 26
Characteristic physical phenotype Long face with large mandible
Large everted ears Large testicles (macroorchidism) Small stature
Mimic connective tissue disorder: Hyperextensible joints High
arched palate Mitral valve prolapse
Slide 27
The childs intellectual level ranges from low average to
severely retarded. Many children have symptoms of attention-deficit
hyperactivity disorder and specific developmental disorders. Female
carriers are usually less impaired than males with fragile X, but
female carriers can manifest the typical physical characteristics
and can be mildly retarded.
Slide 28
Pattern of Transmission Carrier Males: Approximately 20% of
males who, by pedigree analysis and by molecular tests, are known
to carry a fragile-X mutation are clinically and cytogenetically
normal. Affected females: 30% to 50% of carrier females are
affected (ex: mentally retarded), a number much higher than that in
other X-linked recessive disorder. Risk of phenotypic effects: Risk
depends on the position of the individual in the pedigree. For
example, brothers of transmitting males are at a 9% risk of having
mental retardation, whereas grandsons of transmitting males incur a
40% risk.
Slide 29
Diagnosis Although demonstration of an abnormal karyotype led
to the identification of this disorder, PCR-based detection of the
repeats is now the method of choice for diagnosis. With Southern
blot analysis, distinction between premutations and mutations can
be made prenatally as well as postnatally.
Slide 30
EDWARDS SYNDROME Trisomy 18 presence of all or part of an extra
18 th chromosome second most common autosomal trisomy incidence
increases as the mother's age increasesi has a very low rate of
survival, resulting from heart abnormalities, kidney malformations,
and other internal organ disorders very low rate more prevalent in
females caused by a meiotic nondisjunction event
low-set, malformed ears Micrognathia cleft lip/cleft palate
upturned nose narrow eyelid folds (palpebral fissures) ocular
hypertelorism Ptosis short breast bone clenched hands,
underdeveloped thumbs and or nails, absent radius, webbing of the
second and third toes, clubfoot or Rocker bottom feet undescended
testicles in males
Slide 33
TRISOMY 9 having three copies (trisomy) of chromosome number 9
appppear with or without mossaicism with long survival rate
Slide 34
FEATURES: Dysmorphisms in the skull, nervous system, mental
retardation Dysmorphisms in the heart, kidneys, and musculoskeletal
system a small face wide fontanelle prominent occiput Micrognathia
low set ears upslanting palpebral fissures high arched palate short
sternum overlapping fingers limited hip abduction rocker bottom
feet heart murmurs webbed neck.
Slide 35
WARKANY SYNDROME trisomy 8 Chromosomal aberration that has
severe effects on the fetus also found in some cases of chronic
myeloid leukaemia result of karyotypic instability caused by the
bcr:abl fusion gene
Slide 36
FEATURES: retarded psychomotor development moderate to severe
mental retardation variable growth patterns (either abnormally
short or tall stature) an expressionless face many musculoskeletal,
visceral, and eye abnormalities and anomalies
Slide 37
PATAU SYNDROME also known as trisomy 13 and trisomy D is a
chromosomal abnormality in which a patient has an additional
chromosome 13 due to a nondisjunction of chromosomes during
meiosis.
Slide 38
Karyotype of trisomy 13
Slide 39
Manifestations and physical findings Cleft lip or palate
Close-set eyes -- eyes may actually fuse together into one Hole,
split, or cleft in the iris (coloboma)
Slide 40
Extra fingers or toes (polydactyl) Hernias: umbilical hernia,
inguinal hernia Scalp defects (absent skin)
Slide 41
Small eyes Small head (microcephaly) Small lower jaw
(micrognathia) Low-set ears Mental retardation Decreased muscle
tone
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Possible Complications: Complications begin almost immediately.
Congenital heart disease is present in approximately 80% of infants
with Trisomy 13. Complications may include: Breathing difficulty or
lack of breathing (apnea) Deafness Feeding problems Heart failure
Seizures Vision problems
Slide 44
Treatment: Treatment of Patau syndrome focuses on the
particular physical problems with which each child is born. Surgery
may be necessary to repair heart defects or cleft lip and cleft
palate. Physical, occupational, and speech therapy will help
individuals with Patau syndrome reach their full developmental
potential.
Slide 45
Prevention: Trisomy 13 can be diagnosed prenatally by
amniocentesis with chromosome studies of the amniotic cells.
Parents of infants with trisomy 13 caused by a translocation should
have genetic testing and counseling, which may help them prevent
recurrence.