Noonan syndrome
What are the symptoms?
Characteristics of Noonan syndrome include:
- heart defects – the most common being pulmonary valve stenosis, atrial septal defects (see entry Heart Defects) and hypertrophic cardiomyopathy (see entry Cardiomyopathies)
- characteristic facial features, including ptosis (drooping eyelids), hypertelorism (widely spaced eyes), large downward-slanting eyes, flat nasal bridge and short neck with neck webbing and anterior rotation (slanting forwards) of the ears
- short stature.
Additional features may include:
- excess oedema (fluid retention in the body) at birth and slow weight gain
- feeding difficulties with poor sucking and weaning and frequent and/or forceful vomiting in babies which may be assessed as failure to thrive
- mild hearing loss
- dental delay
- elevated or depressed sternum
- hypotonia
- undescended testes (meaning that the testicles stay within the abdomen)
- mild developmental delay in a small number of children
- speech and behaviour problems.
In addition, the characteristics of the syndrome, especially facial, appear to change as the individual ages.
Overlapping syndromes
LEOPARD syndrome, CFC syndrome (see entry cardiofaciocutaneous syndrome), Costello syndrome and neurofibromatosis are all due to defects in the same pathway and have different clinical features. However LEOPARD syndrome is the most similar and due to changes in the same gene PTPN11.
The term LEOPARD syndrome stands for:
- Lentignes (freckles)
- Electrocardiogram (minor abnormalities in the electrical activity of the heart)
- Ocular hypertelorism (widely spaced eyes)
- Pulmonary stenosis
- Abnormalities of the male genitalia
- Retardation of growth
- Deafness.
Background
| Inheritance patterns and prenatal diagnosis 
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