It’s fitting that today of all days thousands of women will get the joyous news that they’re going to be mommies. One of the first and most common tests usually performed (Or perhaps not so common afterall) on the expectant mother is a procedure called amniocentesis. A few cells will be collected from the developing embryo, using a disturbingly long needle, and examined for genetic and other abnormalities. Under a powerful microscope, the 23 pairs of human chromosomes near the center of each cell look kind of like a hopelessly tangled ball of thick, snarled strings. But with just a quick glance, an experienced cytogeneticist can identify each chromosome by characteristic bands and shapes, isolate and photograph them, and array the photos in an easy to read chart called a karyotype.
Of course everyone knows that each parent contributes half of their chromosomes to the developing blastocyst. But how is it that 23 pairs of chromosomes from each of two parents are condensed into a single set of 23 pairs in one child? The answer to that requires some simple arithmetic and few basics, reviewed here courtesy of a brilliant geneticist friend of mine from the Denver Museum of Nature and Science. When most cells divide into two new cells using a process called mitosis, both new cells end up with a complete set of chromosomes. But in related process, called meiosis, only one of each chromosome pair is chosen, meaning the resultant gamete -- fancy name for an egg or sperm cell -- has 23 single or unpaired chromosomes.
Which chromosome from each of the 23 pairs end up in a particular gamete is random. Chromosome 1A might be chosen from pair 1, chromosome 2B might be chosen from pair 2, and so forth. Since there are 23 pairs, the total possible number of combos works out to two raised to the 23rd power, or 8,388,608 possible distinct permutations for each gamete. That's true for both parents, so one couple can produce about 8.388 million squared, or about 70 trillion genetically distinct offspring. But that 70 trillion isn't the whole story. Sometimes the pairs of chromosomes don't separate properly during meiosis, which means the child's genome might end up having more or less than two chromosomes where a single pair is supposed to be. If for example there's a triplet in what's supposed to be the 21st pair, the result is Trisomy 21, more commonly known as Down's Syndrome.
Down's is considered a disease, specifically a chromosomal abnormality. But as anyone with a relative or friend with Down's knows, disease is a rather harsh word. I'm proud to say I have a cousin with Down's Syndrome. My aunt was heavily pressured to turn her special needs son over to an institution (This was in the early 60s), an option she flatly rejected and which served me and my family well. Because of my cousin's gentle, unconditional love and loyalty, he taught me many things for which I'm grateful. Not the least of which is the kind of empathy and respect for my fellow human being that most children don’t learn until much later in life, if ever.
Cytogenetics also plays a critical role in the diagnosis and treatment of other diseases, like cancer. The example right shows one such cancerous karyotype where the usual 23 pairs have been replaced by a bewildering array of duplicates and malformed chromosomes that might not be recognizable as human even to a novice genetics student. The details of those duplicated and malformed chromosomes is one way oncologists zero in on the particular subtype of cancer, which in turns guides them in prescribing the most effective treatment for that specific cancer. Not many people outside of medicine have even heard of cytogenetics. But now you know: the work of these unsung heroes save countless lives, from infants to seniors, every day.
Unlike my cousin with Down's or someone battling cancer, as best I know all my cells -- at least the ones that have a single nucleus -- contain the usual 23 pairs of chromosomes. But in my case there's a twist: none of them come from my mother or father! Like millions of children in America, I was adopted. Despite the customs of those days long past, my parents were wisely and wonderfully progressive. Far from downplaying my adoption, or keeping it secret, from the earliest age I can remember they heartily encouraged me to bring it up anytime I felt like it. Otherwise, I had a completely traditional childhood, wanting for nothing, surrounded by all the love and support any youngin could possibly hope for.
From the perspective of an adopted child, the fact of adoption is purely academic. We don't remember events that transpired when we were only a few days old. I knew my mother as 'mommie' just like any other kid, and lovingly called her that as soon as I was old enough to say my first words. Of course as I got older, from time to time, my friends would ask me about it. But thanks to the wisdom of my mother and father in always being so open about my adoption, I actually felt proud explaining to my peers the story of how my parents went to great lengths and considerable expense over a period of several years, just for the opportunity to choose me!
And so today I want to acknowledge not just my loving mother, but all mothers out there in cyber-land. Thank you, for bearing the physical discomfort and risk of pregnancy for nine long months, followed by an often exhausting, lengthy delivery that would send most of us so-called macho men crawling to the nearest pain management clinic on our hands and knees begging for narcotic relief. Thank you, to the millions of women who marry into an existing family, fill the gaping void, to raise and love the children of their new spouses as if they were their own flesh and blood. Thank you, for the moms who, in today’s harsh economic climate, both work and raise children. Thank you, to the mommy millions that do it all entirely alone, the sole parent, breadwinner, and foundation in their family. Thank those of you here in the progressive movement who, I’m proud to note fight today for mothers who find love, always so elusive and every bit as precious, in same sex relationships and seek only the same respect and equal rights other couples take for granted. And there's a special place in my heart for those seek out and adopt children, children like me, who might never have known the simple, human kindness of a mother's love.
One day hardly seems adequate to honor and celebrate a lifetime of love and devotion. But for what it’s worth, to all the moms reading this, single or married, step or primary, biological or adoptive, gay or straight: from all of us at Daily Kos, with love and gratitude, we wish you a warm and wonderful Mother’s Day!