Asymmetry - Lisa Halliday Page 0,67
said Lachlan. What was that?
I’ve no idea. Do you know what’s wrong with her?
Lachlan shook his head. Only that she’s younger than she looks.
Sometime later, we would learn that the little girl had a rare form of something called congenital adrenal hyperplasia. Normally, a stimulant called adrenocorticotropic hormone, or ACTH, is produced by the pituitary gland and carried by blood down to the adrenal glands, which sit atop the kidneys. There, ACTH announces the need for cortisol, a steroidal hormone having many essential everyday functions. But cortisol doesn’t come spontaneously into existence; it derives from precursors that enzymes convert into cortisol. In a body affected by CAH, the key enzyme is missing, causing the assembly line to break down just before cortisol is made. The result is a buildup of precursors—but never enough cortisol. And since it’s the presence of cortisol that suppresses the dispatching of more ACTH, the pituitary gland sends out more and more ACTH, stimulating the adrenal glands such that they swell to an abnormal size.
Cortisol is required for normal endocrine activity, regulating growth, metabolism, tissue function, sleep patterns, and mood. Untreated, a cortisol deficiency can be fatal, causing hypoglycemia, dehydration, weight loss, dizziness, low blood pressure, even cardiovascular collapse. Also problematic are the symptoms arising from the thwarted cortisol precursors, which include an excess of androgens, otherwise known as the male sex hormones. As a result, a three-year-old boy affected by CAH could develop hair under his arms and acne as bad as his babysitter’s. Likewise, a little girl with it could also exhibit masculine features from an early age: body hair, a growth spurt, even a preference for trucks and tractors over teacups and dolls. When she reaches the normal age of puberty, her voice might deepen, her chest might remain flat, and she might menstruate very lightly, if at all. In theory, few cases should reach this stage of virilization, because earlier signs would have prompted a trip to the doctor, who in turn would have prescribed synthetic steroids to lower the androgen levels in the system.
Sometimes, the problem is even apparent at birth. Instead of having a normal-sized clitoris, a baby having two X chromosomes might be born with an enlarged clitoris that looks like a tiny penis. Her urethra and vagina might have merged toward a single opening and the labia may have fused entirely, resembling a scrotum. Yet an ultrasound will reveal that, inside, she has a perfectly normal uterus, fallopian tubes, ovaries, and a cervix. In fact, were she to have external reconstructive surgery, she would have everything she needs (save someone else’s sperm, of course) in order one day to conceive. My little Arab friend had been born with ambiguous genitalia, but not so ambiguous that her parents, nor an obstetrician back in Syria, had seen fit at the time to call her anything but a girl. More recently, however, certain other signs, including the increasingly phallic anomaly between her legs, had raised eyebrows at home and she was brought in. Indisputably, her cortisol levels needed to be regulated. But there remained the question of what to do about her gender. Her doctors were of the opinion that she should be given hormone-replacement therapy and perhaps also a genitoplasty and carry on as a girl. Her mother was inclined to agree. But her father had a different perspective. Where he was from, a boy is superior. A boy is prestige. A boy brings you pride. Where he was from, one might even say: Better an infertile man than a fertile woman. In fact, said the father, I always thought she was a boy. It was a mistake from the beginning. She looks like a boy. She acts like a boy. Her life would be so much easier if she were a boy. He’s a boy.
There’s no cure for CAH. It’s a genetic condition whereby the double helix inherits two copies of a faulty gene, one copy from each parent. Usually, the gene is recessive to a dominant counterpart. But if both parents are carriers, there’s a 25 percent chance their child will inherit both faulty genes and express the condition. This leaves a 50 percent chance the child will inherit only one faulty gene (and become another carrier), and a 25 percent chance the child will inherit only normal genes, and be unaffected. Owing to the probability that two partners will have inherited the same mutant gene from a common ancestor, autosomal recessive disorders are especially common among the