p53
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A 15-year-old girl presents with a short stature, rounded face, foreshortened fourth metacarpals and obesity. Her biochemical work-up hasn't found any hormonal abnormality. The same phenotype, but with hormonal abnormalities could be present in which relative of this patient?
A. Her father
B. Her mother
C. Son of her father's sister
D. Daughter of her mother's brother
E. Her sister
F. Her brother
Edited by p53 on 08/30/06 - 09:08 PM
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| 99doc
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A.Her father
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| p53
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It's difficult question. In order to answer it, you have to take 2 steps. First step - you must know the diagnosis. Then second step - you must know pattern of inheritance of this disease. Do you know the diagnosis?
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| p53
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Ms.Apara, do you know the diagnosis? if it's difficult, I can give you a tip.
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| Ms.Apara
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Sorry i was not online....... Well the ANS is Her sis.
its quite simple its turner syn so her mom can never hav it, as females r infertile.
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| p53
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I'm sorry, but I'm afraid I have made an error in the answer list of my genetic question and there were 2 correct answer choices. 99doc, you was right, but my question wasn't correct.
So, now I have corrected it and added some relevant info.
Ms.Apara, no, it isn't turner syn and your answer isn't correct.
A 15-year-old girl presents with a short stature, rounded face, foreshortened fourth metacarpals and obesity. Her biochemical work-up hasn't found any abnormality. The same phenotype, but with hypocalcemia and hyperphosphatemia, could be present in which relative of this patient?
A. Her mother
B. Son of her father's sister
C. Daughter of her mother's brother
D. Her sister
E. Her brother
Edited by p53 on 08/30/06 - 09:09 PM
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| Ms.Apara
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Well dear if u open up ur books then for question1 ans E is rite it is turner syndrone.
its not my mistake that the ans u epected that to for a different question was not there.
Mr.99doc answered wrong for what i answered. He may be rite to what is not even posted here.
open page 2216 table 328-1 of HARRISON'S internal medicine 16 th edition.......... u will find the ans to this very question......... 
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| p53
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I think we arn't talking about webbing of neck, broad chest with widely spaced nipples, pigmented nevi and cubitus valgus. No, we are talking about rounded face and foreshortened fourth metacarpals. Yes, these disorders share 2 phenotypic features - short stature and obesity, but foreshortened fourth metacarpals is NOT a stigma of Turner syndrome and at the same time it is a cardinal feature for this disease. So, now, what is the answer for my "second" question?
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| 99doc
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pseudohypoparathyroidism also shows similar physical findings ,it is AR disorder so what can we conclude from it?
in Harison-"the view the disease is X-linked has given way(ALONG WITH CAREFUL FAMILY &MOLECULAR DISORDERS STUDY),that osteodystrophy subset is AD.
going by all this,if we consider it to be X-linked,it must be X-linked dominant as the girl is showing the trait,so may be anything of the above choices.?
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| p53
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yes, this is phenotype of pseudohypoparathyroidism, but what is the answer?
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| Ms.Apara
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This feature is present in turner syn too...... READ THE BOOKS THAT WILL HELP U.........
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| p53
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OK, Ms.Apara, maybe you are right about phenotypes, and we are reading different books, and you have answered correctly "first" question, and that's over, but what about "second" question? what about hypocalcemia and hyperphosphatemia? or maybe they are also features of turner syndrome?
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| 99doc
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please post the answer if u have it.There seems to be a missing link somewhere.
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| p53
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I'll wait with the answer (I'm waiting for Ms.Apara's reply), but now I can say that presented patient actually has pseudo-pseudohypoparathyroidism and her relative - pseudohypoparathyroidism, i.e. Albright's hereditary osteodystrophy, but their phenotypes are the same.
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| Ms.Apara
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Who m i to say anything, i think u people knw much more..............
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| p53
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Don’t underestimate yourself, please.
O.K. here is the answer (rather lenghty, I think).
Both of these disorders (Pseudo-pseudohypoparathyroidism and pseudohypoparathyroidism) are caused by the mutation of the gene GNAS1 encoding Gsa protein associated with Parathyroid Hormone Receptor.
This gene is a selectively imprinted gene, with tissue-specific pattern of imprinting. In most tissues Gsa is expressed from both allels. In the kidneys and the pituitary GNAS1 is expressed only from the maternally inherited chromosome, owing to paternal imprinting (silencing) of the gene. As a result, a mutation that affects the maternal allele results in complete loss of Gsa expression in the kidneys, while a mutation in the normally unexpressed paternal allele has no effect on Gsa level. In contrast, a mutation of either allele will produce a 50% decrease in Gsa in tissues other than the kidneys and pituitary, since GNAS1 is expressed from both copies of the gene (Kumar: Robbins and Cotran Pathologic Basis of Disease, 7th ed.).
Patients with pseudo-PHP often are found in the same kindreds as those with pseudohypoparathyroidism Ia and invariably inherit the abnormal Gs α gene found in their PTH-resistant relatives. When patients inherit the mutant Gs α gene from their fathers, they exhibit pseudo-PHP; when they inherit the mutant Gs α gene from their mothers, they exhibit PHP. This pattern, in which the phenotype depends on the parent of origin, is termed genetic imprinting; The fact that the GNAS1 gene is imprinted has partly resolved the dilemma of this dominant phenotype (Larsen: Williams Textbook of Endocrinology, 10th ed.).
So, presented patient got pseudo-pseudohypoparathyroidism from her father (but her father might have pseudohypoparathyroidism, if he inherited mutated GNAS1 from his mother), not from her mother. Her siblings couldn’t have pseudohypoparathyroidism, they could only have pseudo-pseudohypoparathyroidism. Daughter of her mother's brother couldn’t have pseudohypoparathyroidism – patient’s mother is free of disease (otherwise patient would have pseudohypoparathyroidism), as well as her brother (even if he wouldn’t, his daughter could have only pseudo-pseudohypoparathyroidism anyway). Son of her father's sister could have pseudohypoparathyroidism – right answer is B and now you can understand why I have made an error in my question initially .
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| 99doc
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That was great info.
i never knew about it.
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