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Abnormalities can range from those invisible to the casual onlooker (a high palate, a divided uvula, the projection of soft tissue that hangs down from the back of the mouth) to an obvious defect with a divided upper lip and a large gap in the roof of the mouth.
A cleft lip palate causes difficulty in feeding and speech production. Surgical repair eases these and may eliminate them.
In the great majority of children, the extra material from 9p appears as a separate, small
chromosome.
Children with rare chromosome disorders are at risk for dental problems.
far always revealed
When the blood of parents with an affected child is examined, it has so
normal chromosomes.
One possible solution in this situation is to take a sample of blood from the umbilical cord, as this blood is part of the fetal circulation. This procedure can be risky, however, and one couple at high risk of having a baby with tetrasomy 9p who lost a pregnancy after fetal blood sampling chose instead to have future pregnancies intensively monitored by amniocentesis and ultrasound with the sonographer looking for findings such as an enlarged head, growth delay and palate, lip and kidney anomalies.
A high standard of dental care is important to minimise damage by decay and erosion (by grinding)
failure of the chromosomes
The
most common reason for the extra chromosome is the
eggs or sperm, leading to
an
9 in one parent to separate in the process of preparing the
extra whole chromosome 9.
This extra chromosome is
leaving it
believed to then undergo an unusual type of division,
bottom halves (the long arms) are lost.
(short arms) while the two
with two top halves
Brachycephaly - the head is disproportionately wide
ear-to-ear
A rare chromosomal disorder where there is four copies of the short arm of chromosome 9 (9p) instead of the normal two resulting in various abnormalities.
compared to the measurement from front to back
frequent problem that occurs after birth is hydrocephalus,
The most
usually requiring a shunt to
drain the excess cerebrospinal fluid and
relieve pressure on the growing brain.
Unusually formed nails; a single crease across the palm; incurving fingers, especiallythe fifth finger; short hands and feet with small toe and finger joints
Widely spaced eyes; small skin folds across the inner corner of the eyes; eyes thatslant somewhat downwards; a small lower jaw, set back from the upper jaw;downwards slanting mouth
Low muscle tone, making the body feel floppy (hypotonia)
Unusual head size – small (microcephaly) or large (macrocephaly). Enlarged fluidfilledventricles within the brain (hydrocephaly)
Down’s
Separation failure, termed non-disjunction, is more common in older mothers (as in
higher than
syndrome) and the age of mothers having a child with tetrasomy 9p is slightly
average.
20 to
years (range
The average age of mothers of babies with the mosaic form is 33.7
that of fathers
42 years), compared with a population average of 26-9 years, while
was 34.9 years.
Growth delay before or after birth
Heart defects
Abnormalities of the kidneys or urinary system. In boys, minor anomalies of the genitals or undescended testicles are common.
At birth, wide gaps between the bony plates of the skull. The front soft spot(fontanelle) may be large
Short neck, sometimes with excess skin
Cleft lip, palate or a high-arched palate
A structural heart anomaly has been found in around one third of children and adults with mosaic tetrasomy 9p.
Underdeveloped lungs, possibly due to diminished fetal movement, sometimes with unusual lobe pattern and bronchopulmonary dysplasia
As tetrasomy 9p is most likely to appear to be non-mosaic in blood, it is important that
all babies with the diagnosis made from a blood test have
Biliary atresia
Malrotation of part of the intestine
the body (such as skin or mucous membranes)
tissue from another part of
Diaphragmatic hernia
to show mosaicism.
examined as well, as this is more likely
Underdeveloped bladder
Inflammation of bile duct to the liver, causing blockage of the flow of bile and jaundice.
Diagnosis during pregnancy is more difficult as tetrasomy 9p cells may not be found in fetal cells in amniotic fluid. It is therefore quite possible for a pregnancy to be affected by tetrasomy 9p but for the amniotic fluid or chorionic villus sample to show only cells with normal chromosomes.
Many babies were born with a very large soft spot (fontanelle)
Where there are two different cell lines within the same tissue
or wide spaces between
the bony plates of the skull.
The front fontanelle was also often slow to close and in
one child was still open at age 4.
So long as the parents have normal chromosomes, the extremely unusual sequence of
events that led to a fetus with tetrasomy 9p is very unlikely
Additionally, some babies have an unusual
head shape
to happen again.
When all the cells show tetrasomy 9p
or size (‘strawberry skull’; asymmetric head shape;
Many
couples will want the reassurance of having their next baby’s
Strabismus (squint) or short sight (myopia)
Dimple near the base of the spine
Sunken eyes due to eyeball being recessed within the orbit
Missing or underdeveloped bones
chromosomes tested
during pregnancy by chorionic villus sampling or
head; macrocephaly – large head;
microcephaly – small
amniocentesis.
Although these
techniques do not necessarily show tetrasomy 9p, a normal
result is reassuring.
Missing gallbladder
Umbilical hernia
The outlook for babies diagnosed with tetrasomy 9p is extremely variable.
Developmental delay
A delay in expected development was the first sign of anything wrong.
Signs were first noticed b/w three months and early secondary school age.
Central nervous system (brain and spinal cord) anomaly
Abnormal features of arms or legs. These can include dislocated joints and clubfeet
Typical facial features including wide set eyes, small jaw (chin), oddly formed /positioned ears and a bulbous or beaked nose
•Treatment varies considerable depending on the type and severity of symptom that develop
•Surgery may be needed to correct defects or abnormalities e.g. heart defects, skull and facial abnormalities
In some babies there is little or no effect on development or health, while in others the effects are obvious and sadly survival may not be possible.
Those babies diagnosed with non-mosaic tetrasomy 9p appear to be at greatest risk and typically do not survive the newborn period.
Among boys with a mosaic tetrasomy 9p, eight (out of 19) and three girls (out of 22) were affected.
Three boys were born with undescended testicles (cryptorchidism).
The testicles begin their descent from the abdomen during fetal life and have usually arrived in the scrotum by birth.
When descent does not occur, the testicles can be brought down in a surgical operation and anchored in the scrotum.
The amount of extra chromosome material. Common sense suggests that those with larger extra chromosomes will be more severely affected.
normal
great majority of children with tetrasomy 9p have parents with
The
chromosomes.
But there are some people - and no-one really knows how many
of them there
•Access to programs and services as required e.g. physical therapy, speech therapy, educational support, social, vocational and medical services
•Various other symptomatic and supportive measures
•Genetic counseling and joining a support group is recommended
it.
- who themselves have tetrasomy 9p but are very mildly affected by
A boy with three copies of the section of chromosome 9 between band p13 and p22 shared some similarities with children with an isochromosome 9p, but had no major anomalies apart from enlarged ventricles within the brain. This could suggest that the part of 9p that he did not have extra copies of (9p23 to the tip of 9p) is the part that causes important birth defects.
They can pass it on.
They can also have normal children.
One man with tetrasomy 9p
had two children with normal chromosomes,
resulting in miscarriage.
but his wife also had five pregnancies
A sacral dimple (dimple or hole in the skin just above the crease between the buttocks) is also sometimes seen but is six times as common in babies with non-mosaic tetrasomy 9p as in babies with the mosaic form.
Known difficulties include a squint (strabismus) (3), including exotropia (divergent squint), frequently intermittent, and lack
Tetrasomy 9p is usually found in highest concentrations in blood, so diagnosis in a baby, child or adult means taking and analysing a blood sample.
Confirmation and an estimation of the ratio of normal to tetrasomy 9p cells can use a sample of skin or a scraping from inside the cheek (buccal smear).
of stereoscopic vision (teaming of the eyes) causing loss of 3D vision
and depth perception.
The sacral dimple may be shallow so you can see the base, but stools can collect there before your child is toilet trained, so keeping it clean and protected is important.
Strabismus may be treated with patching, glasses, exercises or surgical
correction.
If there is any concern about this, your baby’s spine will be imaged, usually with ultrasound or an MRI scan.
When only tetrasomy 9p cells and no normal cells are found in both blood and skin cells or amniotic fluid, the effects are likely to be more obvious and more severe. Babies with mosaic tetrasomy 9p survive the newborn period better.
Feeding problems are common
The proportions of tetrasomy 9p cells are different in different body tissues. In blood there are more tetrasomy 9p cells and sometimes no normal cells are found. In other tissues, especially skin and mucous membranes, the proportion of tetrasomy 9p cells is usually lower and no tetrasomy 9p cells may be found. Organs, such as the brain and lungs, may have different proportions again and this variability is very likely to affect the outcome
Breastfeeding
By gastrostomy tube
A variety of unusual features of the skeleton has been reported, including:underdeveloped shoulder blades
missing ribs
a prominent collar bone
underdevelopment of collar bones causing marked sloping of the shoulders
uneven skeletal growth with one side of the body larger than the other, a condition known as hemihypertrophy
An extra chromosome made up of two copies of the same part
Yes, there are. Out of 47 reports in the medical literature, there are three people with apparently normal development and a possible fourth.
Height and body build are variable
children and adults with tetrasomy 9p are loving,
caring individuals and generally speaking
have an open and sociable temperament
The kidneys were affected in more than one baby or child out of three with mosaic tetrasomy 9p.
*cystic kidneys
A multicystic kidney may be removed if it is causing discomfort.
The important thing is to ensure optimal function of the other kidney.
late to achieve their ‘milestones’ of sitting and walking
- helped by regular physiotherapy
Mobility is affected by abnormal muscle tone
- low tone (hypotonia)
- high tone (hypertonia)
Improves with maturity and regular physiotherapy
Some achieve total mobility
abnormalities of foot position
rocker bottom feet
pes cavus (‘claw foot’)
pes planus (flat feet)
(the feet are flat and stick out)
pes planovalgus
pes equinovarus (club feet, with the foot turned
inwards, the soles pointing towards each other)
where the toes point
pes adductus (so-called ‘banana foot’
inwards)
*specific physiotherapy