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Hormone Linked to Male Bias in Autism


AMH may have slown the cognitive development of boys so that 6-year-old boys with very high levels of AMH have brains that are as mature as an average 4.5-year-old girl.

By Ian McLennan

Anti-Müllerian hormone affects the rate of development of boys, leading to a male bias in autism spectrum disorders.

Ian McLennan is Professor of Anatomy at the University of Otago.

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Men and women have different propensities to develop medical conditions, particularly brain disorders. Autism spectrum disorders and motor neuron disease are more common in males, while anoxeria nervosa and depression have a female bias. Schizophrenia tends to be more severe in young males. Our research is asking whether protein hormones released from the testes of boys creates the male gender and contributes to the male biases in some diseases.

The male and female forms are different throughout the entire body, but the nature of the differences varies between tissues. The reproductive organs have distinct female and male forms that have little in common: women have ovaries and a uterus, whereas men have testes and no uterus.

The male and female forms overlap elsewhere in the body, with sex differences only existing when groups of men and women are compared. Men, for instance, are taller than women on average, but a tall woman is still feminine. Such differences do not define a person’s sex. I refer to this type of subtle bias as a gender difference to distinguish them from the larger differences that define a person’s biological sex.

The Creation of Sex and Gender

Embryos are initially asexual, having the precursors of both the male and the female forms. The gross features of females are the default setting, and develop automatically...

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