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The XX Advantage

Women’s bodies are capable of inactivating one of their two X chromosomes within each cell. Without this ability, XX women might not survive. In rare cases, women are born with only one copy of the X chromosome, which results in a disorder known as Turner syndrome that is associated with short stature, ovarian failure and heart issues. The XX mosaic capability seems to be an adaptive ability that evolved to help protect women and the next generation. It will take more research to understand its full effects.

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 Stanford Medicine-led study shows why women are at greater risk of autoimmune disease

Research throws light on the mystery of why women are much more prone to autoimmune disorders: A molecule made by one X chromosome in every female cell can generate antibodies to a woman’s own tissues. Women have too much of a good thing: It’s called the X chromosome. Throughout the mammalian kingdom, biological sex is determined by the presence, in every female cell, of two X chromosomes. Male cells pack just one X chromosome, paired with a much shorter one designated the Y chromosome. The stubby Y chromosome contains only a handful of active genes. It’s quite possible to live a full life without a Y chromosome. In fact, more than half of the people on Earth — women — lack Y chromosomes and do just fine. But no mammalian cell, male or female, can survive without at least one copy of the X chromosome, which holds many hundreds of active protein-specifying genes.

 The Better Half: On the Genetic Superiority of Women review – bold study of chromosomal advantage

Sharon Moalem offers an intriguing theory on how two X chromosomes give women the edge in everything from colour vision to coronavirus. Moalem’s point is that, just as women’s discoveries have been ignored, so too has the importance of their second X chromosome. Even today, medical and pharmaceutical research overwhelmingly favours male subjects, blinding us to knowledge that could lead to breakthroughs, and disadvantaging women who suffer inappropriate treatments and dosing. As men continue to fill the Covid-19 morgues faster than women, Moalem is on a quest to draw the world’s attention to a chromosomal tool we might just need.

Articles of Interest

46,XX Male Syndrome: A Rare Cause of Male Infertility

A rare cause of primary hypogonadism is 46,XX male syndrome, which affects 1 in 20,000 males,1 including our patient. The syndrome, first documented in 1964, was previously known as de la Chapelle syndrome and may also be referred to as 46,XX testicular disorder of sex development. Individuals with 46,XX male syndrome have a male phenotype but a 46,XX genotype.

Female XX sex chromosomes increase survival and extend lifespan in aging mice

Female longevity is observed in humans and much of the animal kingdom, but its causes remain elusive. Using a genetic manipulation that generates XX and XY mice, each with either ovaries or testes, we show that the female XX sex chromosome complement increases survival during aging in male and female mice. In combination with ovaries, it also extends lifespan. Understanding causes of sex‐based differences in aging could lead to new pathways to counter age‐induced decline in both sexes.

Sex Chromosomes Hold the Secret to Female Longevity

Now, scientists at UC San Francisco have zeroed in on a possible genetic mechanism for this highly durable phenomenon, that – while it does not preclude the influence of other biological, social and environmental factors – suggests an important role for the second X chromosome, which is present in female mammals. The X chromosome contains many genes related to the brain, and it is crucial for survival. Without at least one X, an animal cannot live.

The importance of having two X chromosomes

The X chromosome is one of the most unusual chromosomes in mammals, because it is present in different numbers in males and females. There are numerous ramifications of this inherent imbalance. The inequality in genomic dose of X genes is thought to present a major problem, but perhaps for only some gene networks.

What is the difference between an XX chromosome and an XY? Nothing!

There shouldn’t be any distinction due to gender because we are all equal. Now question yourself: Does having an XX chromosome change our abilities rather than having an XY?

Xx Male Syndrome

XX male syndrome, also known as de la Chapelle syndrome, is a rare congenital intersex condition in which an individual with a 46, XX karyotype (otherwise associated with females) has phenotypically male characteristics that can vary among cases. Synonyms include 46,XX testicular difference of sex development (46,XX DSD), 46,XX sex reversal, nonsyndromic 46,XX testicular DSD, and XX sex reversal. In 90 percent of these individuals, the syndrome is caused by the Y chromosome's SRY gene, which triggers male reproductive development, being atypically included in the crossing over of genetic information that takes place between the pseudoautosomal regions of the X and Y chromosomes during meiosis in the father.

Xx Vs Xy Chromosomes: Explained in Detailed

The XX and XY chromosomes determine biological sex in humans and several other species. Females have two X chromosomes, which allow for complete expression of X-linked genes. Males have one X chromosome and one smaller Y chromosome, which mostly contains genes for male development. Interestingly, whereas females exclusively create X-carrying eggs, males generate sperm with either an X or a Y, which ultimately determines the offspring's gender: XX for females and XY for males. This method, known as XY sex determination, is why dads basically "choose" the sex of their offspring.