A Case Study in Sexual Differentiation Part I: Proud Parents to Be

Transcription

1 A Case Study in Sexual Differentiation Part I: Proud Parents to Be Its time! Its time! I m in labor, screamed Maria, a young, healthy mother-to-be at her husband Jose late Friday evening. Living in an isolated village in the Dominican Republic, the only medical provider was miles and miles away, so they needed to get on the road to make it in time. You have a beautiful..umm girl. No boy. No girl, the doctor proclaimed without confidence. What do you mean? We might have a girl or we might have a boy? questioned a concerned new father. Isn t it one or the other? You are the proud parents of a healthy baby girl. The genitalia is enlarged compared to most newborns, but I m sure she ll be fine, explained the confused doctor. Questions: 1. Jose and Maria are now very confused. If their newborn baby is a girl, what sex chromosomes will she have? 2. If their newborn baby is a boy, what sex chromosomes will he have? 3. What is the difference between genetic vs. phenotypic sex? 4. Please explain what a bipotential gonad is? 5. What are the rudimentary ducts for males and females?

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3 Part II: Puberty-oh joy! Teresa, please clean up your room. You cannot leave before its immaculate! exclaimed Maria. Okay, okay I ll do it Mama, replied Teresa in a disturbingly deepening voice. Maria looked on with scorn and admiration in a way that only mother s can; however, she was remembering the first words out of the doctor s mouth twelve years ago. You have a beautiful girl, no boy, no girl. Her firstborn child was born with ambiguous genitalia and the delivering physician couldn t determine the sex with confidence. After a more thorough exam, he explained that she had an enlarged clitoris, but reduced vaginal canal. He suggested that they raise the child as a girl despite a genetic test indicating that the baby girl had X and Y sex chromosomes. And twelve years later that s exactly what they did. They raised Teresa as any other daughter, lots of dresses, dolls, and long pretty hair, but recently, Maria has been noticing that Teresa s voice is cracking as if it s trying to deepen like a boy growing through puberty. I think we might have made a mistake raising Teresa as a girl, stated Maria to her husband Jose. No way, she s clearly a she, retorted Jose. Haven t you noticed her voice is cracking like a twelve year old boy going through puberty? Yes, her voice does crack a bit. I think we should take her to a doctor again and seek their advice. But, this time, can we go to a specialist? Yes, I ll set up an appointment right away. Questions: 1. Is the lack of a second x for males (males genetically:xy) or the lack of a y chromosome for females (females genetically:xx) more important in determining sex? Why? 2. What gene is necessary for testes development? 3. If Teresa is genetically male, what male sex organs does Teresa possibly have?

4 Questions continued: Part II 4. What is Teresa going through? 5. When are hormone levels high during development and/or life? 6. What s one possible explanation that Teresa has an external female phenotype, but genetically male? 7. What are the primary female sex characteristics? 8. What are the primary male characteristics? 9. What are the secondary female sex characteristics?

5 10. What are the secondary male sex characteristics?

6 Part III: Is Teresa a he or a she? Although anxious, Teresa was happy to be going to a specialist, so that she could get some questions answered. She knew that her body would change a lot going through puberty, but knew that she felt different than the rest of the girls. Test results show that you are a healthy, growing young adult, but that you have a genetic disorder that disrupts your ability to make dihydrotestosterone. You do not have the enzyme 5-alpha reductase, stated the physician. What does an enzyme have to do with making the D word you just said? Is the D word important? questioned Teresa. Dihydrotestosterone is the most potent form of androgens and is necessary during development for male genitalia in utero. 5-alpha reductase is what converts testosterone into dihydrotestosterone, answered the physician. So I can make testosterone? I thought that was the male hormone, responded Teresa. Testosterone and dihydrotestosterone activate the same receptor on a cell, but dihydrotestosterone activates the receptor more effectively than testosterone. It is more potent than testosterone, explained the physician. He continued, With puberty, there is a rise in testosterone that compensates for your lack of dihydrotestosterone. Your body is going to start developing secondary male characteristics. Although, you have primary female sex characteristics, you will develop male secondary sex characteristics with puberty. It is somewhat common in the Dominican Republic and you are referred to as Guevedoche or penis at twelve. With puberty, your external genitalia may develop into a micropenis. You are genetically male with X and Y sex chromosomes. You have testes, but they have not descended yet. With puberty, the testes should descend also. Questions: 1. Why does Teresa present primary female sex characteristics? 2. What duct (mullerian or wolffian) developed? And why? 3. What do wolffian ducts develop into?

7 Questions continued: Part III 4. What do mullerian ducts develop into? 5. Why is this condition also coined the term penis at twelve? 6. What internal sex structures may a person with this condition have? 7. Is sex a dichotomy? Why or why not? 8. What ethical issues are present in this condition?

8 9. Should parents conduct surgical procedures to correct ambiguous genitalia? NOTE: Pullitzer Prize winning book written on this condition called Middlesex