All of the following may occur in Noonan's syndrome except:
1.Hypertrophic cardiomyopathy.
2.Cryptoorchidism.
3.Infertility in females.
4.Autosomal dominant transmission.
Answer
3.Infertility in females.
Reference
Nelson 15th Edition Chapter 535
Harrison 15th Edition Chapters 328, 338 and Page 2175
Quality
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Harrison
Discussion
The term Noonan syndrome has been applied to phenotypic males and females who have certain anomalies that occur also in females with Turner syndrome. These boys and girls have normal karyotypes. The disorder is usually sporadic, but affected siblings of the same and of different genders have been reported. Total or partial expression is present in 20% of relatives. Reports of male-to-male transmission suggest an autosomal dominant gene with variable expressivity. The gene has been mapped to chromosome 12q.
The most common features are
1. Normal Karyotype
2. Normal Sex Chromosomes
3. Normal Gonads in females
4. Short stature,
5. Webbing of the neck,
6. Pectus carinatum or pectus excavatum,
7. Cubitum valgum,
8. Congenital heart disease, (most often Hypoertrophic Cardiomyopathy, pulmonary valvular stenosis or atrial septal defect)
9. Characteristic facies.
10. Hypertelorism,
11. Epicanthus, an
12. Antimongoloid palpebral slant,
13. Ptosis,
14. Micrognathia, and
15. Ear abnormalities (High Frequency Sensineural hearing loss) are common.
Other abnormalities such as
16. Clinodactyly,
17. Hernias, and
18. Vertebral anomalies occur less frequently.
19. Moderate mental retardation occurs in 25% of patients.
20. Males frequently have cryptorchidism and small testes; they may be hypogonadal or normal.
21. In females Puberty is delayed 2 yr on average; adult height is achieved by the end of the 2nd decade and usually reaches the lowest limit of the normal population.
22. No Primary Gonadal Failure in Females
Explanation
- Hypertrophic cardiomyopathy is seen.
- Cryptoorchidism is present.
- Infertility in females is not present.
- Autosomal dominant transmission is the rule.
Comments
Note that Noonan can occur in both Males and Females and there is Hypogonadism and Cryptorchidism in Males and Normal Gonads in Females and we have Pulmonary Stenosis and ASD (Every one knows the defect in Turners!!!)
Tips
Forget the popular saying that Noonan is Male Turner. It occurs in both males as well as in females
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Source of this Question: RxPG AIPG 2004
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