GENOTYPE
Noonan syndrome is hereditary; however, it can appear within the family even when it is not in the
families’ genetic line.There are multiple genes reasonable for Noonan’s
syndrome PTPN11, SOS1, RAF1, KRAS, NRAS and BRAF the gene PTPN11 is the most
common among patients with Noonan. PTPN11 accounts for at least half of the
patients while SOS1 accounts for ten percent, RAF1 accounts for five to ten
percent and KRAS accounts for 2 percent. It is unknown how many cases KRAS, NRAS
and BRAF account for. The gene PTPN11 codes for SHP-2 protein which plays a role
in signal transduction. That includes signaling RAS-mitrogen activated protein
kinas.
families’ genetic line.There are multiple genes reasonable for Noonan’s
syndrome PTPN11, SOS1, RAF1, KRAS, NRAS and BRAF the gene PTPN11 is the most
common among patients with Noonan. PTPN11 accounts for at least half of the
patients while SOS1 accounts for ten percent, RAF1 accounts for five to ten
percent and KRAS accounts for 2 percent. It is unknown how many cases KRAS, NRAS
and BRAF account for. The gene PTPN11 codes for SHP-2 protein which plays a role
in signal transduction. That includes signaling RAS-mitrogen activated protein
kinas.
PHENOTYPE
Noonan syndrome can be diagnosed with several different physical appearances such
as
• Short stature.
• Heart defect present at birth (congential heart disease)
• A broad or webbed neck.
• Minor eye problems such as strabismus in up to 95 percent of individuals.
• Bleeding problems such as a history of abnormal bleeding or bruising.
• An unusual chest shape with widely-spaced and low set nipples.
• Developmental delay of varying degrees, but usually mild.
• In males,undescended testes (cryptorchidism)
Sometimes these features are unnoticeable unless carefully looked at from birth to an
older age in the child. Children born with Noonan syndrome will usually be a
normal length at birth, and their short stature will not usually become apparent
until they are around two years old. After that time, they won't grow as quickly
as children of the same age. Puberty will usually be delayed for up to two
years. The expected growth spurt that should happen during puberty is either
very little or doesn’t happen at all. This is may be treated with a type of
medication known as human growth hormone.
Around ninety percent of children with Noonan syndrome have cognitional heart disease which
can be Pulmonary stenosis (most common (the valve that helps control the flow of blood away from the heart and
into the lungs is unusually narrow) to Hypertrophic cardiomyopathy (the muscles of the heart are much larger than they should be. Which can lead to
breathlessness) or sepal defect (The hole can be between the upper chambers or the lower chambers).
·
Bruising or bleeding.
Easy bruising or bleeding affects nearly fifty percent of the
patients. This makes their skin more vulnerable to bruising and they may lose
more blood than normal from cuts. If your child is affected and needs surgery or
dental work, they will need to be watched for longer than usual afterwards, in
case of bleeding.
·
Eye conditions.
Around half of children with Noonan syndrome will have one or more
eye conditions, including: a squints, where one eye does not look straight ahead
but turns inwards, outwards, upwards or downwards astigmatism, where the cornea
(the transparent layer at the front of the eye is not a perfectly shaped curve,
causing symptoms such as blurred vision lazy eye, where one eye is less able to
focus than the other eye, leading to an increasing reliance on the more
effective eye .
·
Lymphatic systems.
Children with Noonan syndrome will have problems with their lymphatic
system. Most commonly this causes a build-up of lymph fluid in their feet
resulting in severe swelling. This is known as
lymphedema.
·
Hypertonia is decreased muscle tone, where the muscles are ‘rag-doll’ appearance. Most children with Noonan syndrome
will have a degree of hypertonia, which may mean it takes them longer to reach developmental milestones during early childhood.
·
In around 60% of boys with Noonan syndrome, either one or both of their testes fails to
descend into the scrotum (the bag that holds the testicles). It is important
that this is corrected through surgery at an early age, to avoid reduced
fertility in later life. In addition, many older males who have not had early
corrective surgery may have a reduced sperm
count.
as
• Short stature.
• Heart defect present at birth (congential heart disease)
• A broad or webbed neck.
• Minor eye problems such as strabismus in up to 95 percent of individuals.
• Bleeding problems such as a history of abnormal bleeding or bruising.
• An unusual chest shape with widely-spaced and low set nipples.
• Developmental delay of varying degrees, but usually mild.
• In males,undescended testes (cryptorchidism)
Sometimes these features are unnoticeable unless carefully looked at from birth to an
older age in the child. Children born with Noonan syndrome will usually be a
normal length at birth, and their short stature will not usually become apparent
until they are around two years old. After that time, they won't grow as quickly
as children of the same age. Puberty will usually be delayed for up to two
years. The expected growth spurt that should happen during puberty is either
very little or doesn’t happen at all. This is may be treated with a type of
medication known as human growth hormone.
Around ninety percent of children with Noonan syndrome have cognitional heart disease which
can be Pulmonary stenosis (most common (the valve that helps control the flow of blood away from the heart and
into the lungs is unusually narrow) to Hypertrophic cardiomyopathy (the muscles of the heart are much larger than they should be. Which can lead to
breathlessness) or sepal defect (The hole can be between the upper chambers or the lower chambers).
·
Bruising or bleeding.
Easy bruising or bleeding affects nearly fifty percent of the
patients. This makes their skin more vulnerable to bruising and they may lose
more blood than normal from cuts. If your child is affected and needs surgery or
dental work, they will need to be watched for longer than usual afterwards, in
case of bleeding.
·
Eye conditions.
Around half of children with Noonan syndrome will have one or more
eye conditions, including: a squints, where one eye does not look straight ahead
but turns inwards, outwards, upwards or downwards astigmatism, where the cornea
(the transparent layer at the front of the eye is not a perfectly shaped curve,
causing symptoms such as blurred vision lazy eye, where one eye is less able to
focus than the other eye, leading to an increasing reliance on the more
effective eye .
·
Lymphatic systems.
Children with Noonan syndrome will have problems with their lymphatic
system. Most commonly this causes a build-up of lymph fluid in their feet
resulting in severe swelling. This is known as
lymphedema.
·
Hypertonia is decreased muscle tone, where the muscles are ‘rag-doll’ appearance. Most children with Noonan syndrome
will have a degree of hypertonia, which may mean it takes them longer to reach developmental milestones during early childhood.
·
In around 60% of boys with Noonan syndrome, either one or both of their testes fails to
descend into the scrotum (the bag that holds the testicles). It is important
that this is corrected through surgery at an early age, to avoid reduced
fertility in later life. In addition, many older males who have not had early
corrective surgery may have a reduced sperm
count.