- Indications of genetic testing!

Medical applications (indications of genetic testing, karyotyping, chromosomal culture, analysis) :

1.     Multiple congenital anomalies:

Birth defects > one developmental regions of the body

A.    Confirmation of a clinical diagnosis

B.    Estimate recurrence risk of future sibling

2.     Dysmorphic features or well-defined syndrome e.g down syndrome

3.     Unexplained Mental retardation (chromosomal abnormalities are responsible for 1/3  50% of MR which is due to genetic factor)   

4.     Pubertal failure

5.     Ambiguous genitalia

Provide diagnosis e.g turner, klinfilter

If Normal karyotyping → other endocrinal disorders

6.     Infertility: at least 5% of infertile men are killfilter.

7.     Recurrent spontaneous Abortions and miscarriage:

≥ 2 spontaneous abortions

At least 15% of all pregnancies end in spontaneous miscarriage

50% of these cases is due to chromosomal abnormalities of which

ü  >50% → due to autosomal trisomies e.g 22 , 16

ü  20% → due to Turner

ü  20% → due to Triploidy , tetraploidy         

ü  10% → Others

8.     Unexplained stillbirths:

ü Chromosomal abnormalities account for 5% of all stillbirth & 5% of neonatal death.

ü Trisomy 18 is the most common abnormality in still birth.

9.     primary amenorrhea

10. Short stature of unknown cause

11. Parents of individuals with chromosomal abnormalities

12. Prenatal diagnosis

13. Malignancy &chromosomal breakage syndromes:

Certain types of malignancy e.g leukemia, retinoblastoma, wilms tumour are associated with specific chromosomal abnormalities. 

Not done for well-defined syndrome caused by something other than chromosomal abnormalities e.g rubella syndrome.

Genetic tests can be thought of as diagnostic, predictive or for carrier status. Informed verbal, and increasingly written, consent (or assent) should be obtained before genetic testing.