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Genetics/Query regarding skin colour

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Question
I have a query regarding my childs skin colour.
My child who is 2 years old is slightly darker then both myself and my wife.
My wife and myself are both fair
How is this possible?
Kindly answer

Answer
Hi Rupesh!

Skin color and hair color are very popular questions. Unfortunately human pigmentation is something we don't understand all that well yet genetically.

Genetics can be thought of as the 'cards' we're dealt at conception. What does this mean? When a lady makes egg cells, her body takes all her genes, shuffles them like cards, and then deals out one-half a deck to each cell. Guys do the same thing with sperm cells. When a baby is made, each DNA half-decks are combined to make a full deck of genes per child. The number of cards (genes) is fixed. However, the pictures on the cards are not 'one of two colors or four suits'. Really, human inheritance has many possible pictures for each card number. We call different pictures in each card position 'alleles'. The total combination of card values/alleles will affect the outward appearance of your children, and you get one allele from each parent.

What about skin or hair color/texture? If we imagine a person as a factory, there is a whole department in the factory dedicated to producing the two known pigment genes, eumelanin (brownish) and pheomelanin (reddish). There are also support staff that indicate when the pigment is produced, how it is delivered, and where it goes, as well as how much the workers make. All of these factors are also controlled by DNA variations. What color we see at the end is a summation of the entire department's efforts, which could be ten or more genes. Also, the instructions on what to make can vary over time given how old the person is. Most often people's hair darkens at maturity, then grays at seniority, but this is not a hard and fast rule. For skin, it may be easier to tan when young, but the genes for pigment aren't made as much in old age.

As you might surmise, all of this is completely a function of statistics. Odd and new combinations can and do happen. I cannot tell you exactly why your child is a bit darker than you. We may be able to in ten years, especially if you get yourselves and her sequenced genetically. In any case, every child is an unique combination of genes, a mix of both parents. It's an adventure.

There's a lot to read out there, and here's a start. Hopefully what I told you makes sense. Please feel free to come back if you have questions.
http://www.gnxp.com/MT2/archives/001516.html
http://www.babyzone.com/pregnancy/fetal-development/baby-appearance_71319
http://www.naturallycurly.com/curlreading/hairstyles/curly-hair-gene

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Trista Robichaud, PhD

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No homework questions, especially ones copied and pasted from textbooks. I will answer questions about principles or give hints, but I do not do other's homework. I'm comfortable answering basic biochemistry, chemistry, genetics, and biology questions up to and including an undergraduate level of understanding. This includes molecular biology, protein purification, and genetics. My training/inclination is primarily in structural biology, or how the shapes of things affect their function. Other interests include protein design, protein engineering, enzyme kinetics, and metabolic diseases such as cancer, atherosclerosis, and diabetes. Regrettably, I cannot diagnose any disease. I can tell you how we currently understand the basic science behind a disease state, but I cannot recommend treatment in any way. Please direct such questions to your medical professional.

Experience

I hold a PhD in Biomedical Science from the University of Massachusetts Medical School in Worcester. I specialize in Biochemistry, with a focus on protein chemistry. My thesis work involved the structure and functions of the human glucose transporter 1. (hGLUT1) Currently I am a postdoc working in peptide (mini-protein) design and enzymology at the University of Texas Health Science Center in San Antonio, Texas. I am in Bjorn Steffensen's lab, researching inhibitors of gelatinase A, a matrix metalloproteinase. I have also been answering Chemistry/Biochemistry questions on this site since summer 2010.

Organizations
2001 American Association for the Advancement of Science, 2007 American Chemical Society 2007 Protein Society 2011 UTHSCSA Women’s Faculty Association

Publications
Publications Levine KB, Robichaud TK, Hamill S, Sultzman LA, Carruthers A. Properties of the human erythrocyte glucose transport protein are determined by cellular context. Biochemistry 44(15):5606-16, 2005. (PMID 15823019) Robichaud TK, Appleyard AN, Herbert RB, Henderson PJ, Carruthers A “Determinants of ligand binding affinity and cooperativity at the GLUT1 endofacial site” Biochemistry 50(15):3137-48, 2011. (PMID 21384913) Xu X, Mikhailova M, Chen Z, Pal S, Robichaud TK, Lafer EM, Baber S, Steffensen B. “Peptide from the C-terminal domain of tissue inhibitor of matrix metalloproteinases-2 (TIMP-2) inhibits membrane activation of matrix metalloproteinase-2 (MMP-2)” Matrix Biol. 2011 Sep;30(7-8):404-12. (PMID: 21839835) Robichaud TK, Steffensen B, Fields GB. Exosite interactions impact matrix metalloproteinase collagen specificities. J Biol Chem. 2011 Oct 28;286(43):37535-42 (PMID: 21896477) Poster Abstracts: Robichaud TK, Carruthers. A Mutagenesis of the Human type 1 glucose transporter exit site: A functional study. ACS 234th Meeting, Boston MA. Division of Biological Chemistry, 2007 Robichaud TK, Bhowmick M, Tokmina-Roszyk D, Fields GB “Synthesis and Analysis of MT1-MMP Peptide Inhibitors” Biological Chemistry Division of the Protein Society Meeting, San Diego CA 2010 Robichaud TK; Tokmina-Roszyk D; Steffensen B and Fields GB “Exosite Interactions Determine Matrix Metalloproteinase Specificities” Gordon Research Conference on Matrix Metalloproteinase Biology, Bristol RI 2011

Education/Credentials
INSTITUTION AND LOCATION DEGREE (if applicable) YEAR(s) FIELD OF STUDY Oakland University, Auburn Hills MI BS 1993-1998 Biochemistry University of Massachusetts Medical School, Worcester MA PhD 2001-2008 Biochemistry & Molecular Pharmacology University of Texas Health Science Center, San Antonio TX Postdoc 2009-Present Biochemistry

Awards and Honors
1998 Honors College Graduate, Oakland University 2009 Institutional National Research Service Award, Pathobiology of Occlusive Vascular Disease T32 HL07446 2011 1st Place, Best Postdoctoral Poster, Dental Science Symposium, UTHSCSA, April 2011

Past/Present Clients
Invited Seminars: Robichaud TK, Fields GB. “Synthesis and Analysis of MTI-MMP Triple Helical Peptide Inhibitors” Pathology Research Conference, University of Texas Health Science Center San Antonio Pathology Department (June 18th, 2010) Robichaud TK & Hill, B “How To Give A Great Scientific Talk” Invited Lecture, Pathobiology of Occlusive Vascular Disease Seminars, UTHSCSA (Nov 11th 2010), Cardiology Seminar Series, Texas Research Park (Feb 21st, 2011) Robichaud TK; Tokmina-Roszyk D; Steffensen B and Fields GB “Exosite Interactions Determine Matrix Metalloproteinase Specificities” Gordon-Keenan Research Seminar “Everything You Wanted to Know About Matrix Metalloproteinases But Were Afraid to Ask” Bristol, RI (Aug 6th, 2011)

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