sing
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A 10-year-old male presents to the pediatrician's office with poor academic performance. His past medical history reveals that he is deaf, is moderately mentally retarded, and has ‘stiff joints.’ On exam, you note short stature and coarse facies. An eye exam reveals that the corneas are clear. An oral exam shows a large tongue. Heart, lung, and abdominal exams are within normal limits. The complete blood count and electrolytes are normal, but the patient's urine is positive for increased dermatan sulfate and increased heparan sulfate. In which enzyme is this child most likely deficient?
A. Alpha-iduronidase
B. Beta-glucuronidase
C. Heparan sulfamidase
D. Iduronosulfate sulfatase
E. N-Acetylglucosaminidase
A&Y
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| bozhenka
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The enzymes deficient in Morquio syndrome are galactosamine-6-sulfatase (ie, N-acetyl-galactosamine-6-sulfate sulfatase) and beta-galactosidase
So, only B is correct (i hope i'm right)
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| sing
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the correct answer is c. i also don't know why. could anyone explain?
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| bozhenka
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MPS type III-A (Sanfilippo syndrome type A) - Heparan sulfate sulfamidase deficiency
The main findings of MPS type III (Sanfilippo syndrome) are regression of psychomotor development and neurologic signs (eg, hyperactivity, autistic features, behavioral disorder), which occur in children aged 2-6 years.
Dysmorphic features are relatively rare.
Other signs include thickened facial features, coarse hair, genu valgum, and a short neck. Hirsutism is common.
Children become inattentive and deteriorate rapidly, losing the power of speech.
Mild hepatosplenomegaly is common.
The course of the disease is progressive; most patients die before the age of 20 years.
That's all that I found about this theme.
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| sing
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thanks a lot.
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| royalgeorge
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Hi GUYS your reasoning & answer is wrong. Lets go throgh the question once more to arrive at the answer.
A 10-year-old male presents to the pediatrician's office with poor academic performance. His past medical history reveals that he is deaf, is moderately mentally retarded, and has ‘stiff joints.’ On exam, you note short stature and coarse facies. An eye exam reveals that the corneas are clear. An oral exam shows a large tongue. Heart, lung, and abdominal exams are within normal limits. The complete blood count and electrolytes are normal, but the patient's urine is positive for increased dermatan sulfate and increased heparan sulfate. In which enzyme is this child most likely deficient?
Keeping all the highlighted points in mind , clear corneas are seen only in MPS 2 (Hunter), & MPS 7 (Sly disease) & it may be minmal in MPS 3 (Sanfillipo) BUT IS USUALLY PRESENT .
urine is positive for increased dermatan sulfate and increased heparan sulfate : Hunter & Sly disese & MPS 1 (Hurler)
Only Heparan SO4 : Sanfillipo
Keratin & Chondroitin: Morquio
So taking these two points into consideration the choice narrows down to Hunter or Sly disease.
But both these choice are present
Hunter: Iduronosulfate sulfatase
Sly disease: Beta-glucuronidase
So how to differentiate between the two , the clue is in the age and sex of child as only hunter is x linked & child with hunter will be moderately affected at 10 years of age so the correct
ANSWER IS : HUNTER & CHOICE D IS CORRECT
My references are
Fenichel : Clinical pediatric neurology
OPGhai : Essential pediatrics
Hope this answers the doubt clearly
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