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NBME 16 Answers

nbme16/Block 1/Question#25 (reveal difficulty score)
A 1-year-old boy is brought to the physician ...
Inability to produce melanin ๐Ÿ” / ๐Ÿ“บ / ๐ŸŒณ / ๐Ÿ“–
tags: biochem derm repeat

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 +2  upvote downvote
submitted by โˆ—okokok1(38)

Albinism: Normal melanocyte number with DECREASED melanin production due to decreased tyrosinase activity or defective tyrosine transport. risk of skin cancer.

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okokok1  the choice "decreased number of epidermal melanocytes" is vitiligo. +7
fatboyslim  @okokok1 isn't vitiligo immune destruction of melanocytes (choice C)? Maybe it's both. Since if you destroy the melanocytes you will have fewer numbers of them in the epidermis? +

In the same vein, a darker-skinned person would have an increased number of melanosomes. BUT the SAME number of melanocytes and melanophages as a lighter-skinned person.

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submitted by โˆ—tamarafainblout(1)

why cant it be A? Aren't melanocytes derived from neural crest cells?

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submitted by โˆ—the_enigma28(69)

Child has albinism. Defective melanin synthesis due to deficiency of enzyme tyrosine hydroxylase. FA 2020, page 476

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topgunber  tyrosinase. tyrosine hydroxylase would make L-dopa +2
sabrooza  It is Tyrosinase deficiency not (Tyrosinase hydroxylase ) +1

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