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A 9yr old boy is referred to a pediatric clinic by his school psychologist because of his poor academic performance,cognitive delay,and hyperkinetic behavior.Family history is significant for early dementia and ataxia in the maternal father.Physical exam reveals the boy has a long thin face with prominent ears,some facial asymmetry and a prominent forehead and jaw.His vital signs are normal,lungs clear to auscultation ,heart sounds normal,abdomen soft, nontender and nondistented. Examination of the extremity showed hyperextensible finger joints.The examining physician suspects a possible genetic disorder.What would be the best test to diagnose this disease?

A.Brain MRI

B.Cytogenetic testing for fragile X

C.Developmental evaluation by a speech or language therapist


E.Measurement of testicular volume

F.Southern Blot Analysis


F: southern blot analysis.nod


Klinefelters - Choice E.


I'll pick B.


Tiff wrote:
Klinefelters - Choice E.

Whether it's Klinefelter's or not, isn't 9 yrs too early to diagnose on testicular volume. He's pre-pubertal.


i l also pick B...usavvy plz tell the ans


F.Southern blot analysis
Boy has Fragile X Syndrome which is a triple nucleotide repeat(CGG)disorder.Identification of triple repeats by molecular genetic techniques is the best way to diagnose these disorders.
Triple repeats can be identified by southern blot analysis or by amplification of the repeat by PCR.
Cytogenetic testing for fragile X can sometimes be false negative and measurement of testicular volumes may be helpful only in postpubertal males.


It could be B, and E . I think nowdays it would be more Southern blot analysis in the Fragile X disease.

Usmlesavvy, what is the answer ?


Patient is showing all the signs of Klinfelters which is diagnosed by karyotyping which isn't an option. However, adolescents as well as older boys will have small testes which is why I opted for testicular volume - Choice E. But that's just what I think. Would love to know what the answer is usmlesavvy.


After re-reading this question, it does say there was "early dementia and ataxia in the maternal father". Which makes me more inclined to now think it's Fragile X. And if so, then Southern Blot would be most ideal.


pt is showing signs of fragile X....???
dementia...prominent ears,prominent forehead,prominent jaw...


i l go with pr20.....for diagnosis of fragile we use either PCR or Southern blot


Fragile X. Answer is F.


nodsouthern blot is the most appropriate diagnostic tool in patients of fragile X syndrome....

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