Syndrome of Noonan

The syndrome of Noonan is a Genetic disease associating:

a characteristic facies
a small size
a congenital Cardiopathie,
a small size with a Neck broad or webbed,
an unusual aspect of the Thorax with low establishment of the nipples
a Backwardness of very variable degree
often of the anomalies of the blood Coagulation

Etiology

Three genes are known like person in charge of the syndrome of Noonan

Mutation of the Gène PTPN11 protein tyrosin phosphatase, non-receptor standard 11 of the Locus q24.1 of the Chromosome 12 found in 50% of the cases. The gene PTPN11 code Protein-Tyrosin Phosphatase Nonrecepteur-Type 11.
Change of the Gene KRAS
Change of the Gene SOS1

Private clinic

The diagnosis of the syndrome of Noonan is often made established clinically well:

characteristic Faciès

the Oreille S established low and is directed behind and the isolated eyes, philtrum deep, edges vermilion of the higher Lèvre, small neck with low establishment of the Cheveu X.
the facial characteristics are clear at the newborn and tend to disappear with the growth.

Small size

the size with the birth is normal but at the adulthood, their size is in extreme cases lower of the normal.

Cardiopathie congenital

This pathology is present between 50 and 80% of the children reached. The cardiac anomaly most frequent is a pulmonary valvular Sténose associated with a Cardiomyopathie of the ventricle gauche.
Of other anomalies were described including/understanding inter-auricular Communication, inter-ventricular Communication, Sténose of the branches of the pulmonary artery, Tétralogie of Hand lantern.

Backwardness

the backwardness reaches 30% of the children but the majority can follow a normal schooling with sometimes a complementary support. The verbal performances are weaker than the nonverbal performances;

Turbid of coagulation:

Disease of Willebrand, Thrombocytopenia and deficit of several factors of coagulation often involving abnormal Bleeding S.

Various

Puberty delayed at the girls but Fertilité normale.
the boys very often has a Cryptorchidie bilateral.

Diagnosis

The diagnosis is primarily based on the clinical .
The research of the change is found only in 50% of the individuals carrying this disease.

Differential diagnosis

This disease must be distinguished from other pathologies associating characteristic face, congenital cardiopathy and backwardness:

Transmission mode

dominant autosomic Transmission but the majority of the affected individuals is the result of a change of novo
But 30 to 50% of the parents of children reached are carrying a change on gene PTPN11

Prenatal diagnosis

The prenatal diagnosis is possible by Prélèvement of trophoblaste or of Amniocentèse but the change must be known before the diagnosis

The genetic Council

A consultation of genetics is essential.

Sources

Site on the syndrome of Noonan
Site of information on the orphan rare diseases and drugs
Site impossible to circumvent for the genetic diseases
Site giving of very pointed descriptions of the genetic diseases

References

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