Posts: 3,675,937
Threads: 734,344
Joined:
Sep 2021
Reputation:
5
A 1 yr old boy is brought to the physician for an examination .Mother is concerned because her son's fine pale hair has not changed colour , his eyes are blue .during examination the pt turns away from the flashlight and starts crying .What is the most likely cause of the pale skin color in this patient ?
A) aberrant migration of neural crest cells
B ) decreased number of epidermal melanocytes
C) immune destruction of melanocytes
D) inablity to produce melanin
E) melanin dropout in Dermis
A versus D and vice versa ?
Though got it correct but it was luck.How to know in exam for sure ?
B and C are vitiligo .What could option E be ?
Posts: 3,675,937
Threads: 734,344
Joined:
Sep 2021
Reputation:
5
A is a separate condition called piebaldism. E could be poliosis.
Posts: 3,675,937
Threads: 734,344
Joined:
Sep 2021
Reputation:
5
Thankyou .Did you google this for me or were you taught in school ?
Posts: 3,675,937
Threads: 734,344
Joined:
Sep 2021
Reputation:
5
Can you have a look at the "NBME 17 -genetics doubt " question ? I think you can explain it very well
Posts: 3,675,937
Threads: 734,344
Joined:
Sep 2021
Reputation:
5
Albinism, number of melanocytes (neural crest migration) is NORMAL
Number of melanosomes (organelle that makes melanin) is NORMAL
Amount of melanin per melanosome, is LOW,
Because of lack of TYROSINASE.
Phenyl Alanine [Phe Hdroxylase, BH4 Tetrahydrobiopterin]-> Tyrosine [Tyr Hydroxylase,BH4]->DOPA [Tyrosinase]-> Bunch of reactions (requires copper, so Menke folks can have pale skin as well) that make *Melanin*
A rare variant, is OCA. Oculocutaneous albinism, this has to be differenciated from stuff like Chediak Higashi, those guys have mild coagulopathy giant platelets, and macrophages with cytoplasmic granules, and a lot of developmental issues later on. History doesn't give features pointing towards that (option didn't have that as well)
Abbarent neural crest migration will cause low melanocytes, low melanosomes, and absent melanin.
One sequale of that, is Piebaldism. Pibaldism (mutation of kit gene on chromosome 4) is benign, white forelock of hair, with no other issues.
A subtype of piebaldism, is Klein Warrenburg (pax-3) mutations, those kids have heterochromia iridia, white forlock of hair(POLIOSIS), deafness and a lot of development issues.
Posts: 3,675,937
Threads: 734,344
Joined:
Sep 2021
Reputation:
5
Melanin dropout is stuff like inflammatory hyperpigmentation
Posts: 3,675,937
Threads: 734,344
Joined:
Sep 2021
Reputation:
5
Thanks .Thats a lot of good information
