DSDs reveal sex development as a multi-step process: five pathways and implications for care

Source

The Conversation

This article explains that biological sex is not a single switch but a developmental sequence spanning birth and puberty. It introduces disorders of sex development (DSDs) as a framework for understanding how bodies can diverge from the typical pattern and emphasizes the importance of clear information, psychological support, and cautious medical care.

Key points

• Sex development is a multi-step process involving chromosomes, gonads, hormones, and the body’s response to hormones.
• DSDs arise when one step in the normal sequence alters development, leading to diverse bodies and medical needs.
• The article outlines five pathways to atypical sex development, including congenital adrenal hyperplasia, complete androgen insensitivity, 5-alpha-reductase deficiency, and sex chromosome disorders such as Klinefelter, Turner, and Swyer syndromes, with guevedoces highlighted as a local example.
• It argues for better information, specialized care, and long-term support while acknowledging that DSDS do not resolve debates about sex and gender, but they illustrate sex as a process rather than a single event.

Overview: sex development as a process

The article develops the argument that biological sex emerges through a sequence of events that begins before birth and continues through puberty. Chromosomes influence gonad formation, gonads produce hormones, and the body’s tissues respond to these hormones. While most people follow the typical sequence, rare cases diverge, creating disorders or differences of sex development (DSDs). These conditions illuminate how a single altered step can change outcomes, producing a spectrum of bodies, medical needs, and life experiences.

The piece emphasizes that DSDS are not new discoveries; rather, advances in genetic testing and patient-centered care have sharpened our understanding and the information provided to families. It also notes that conditions affecting sex development have often been surrounded by silence, which has impeded recognition and proper care. The author argues for information, psychological support, and cautious decision-making around irreversible childhood surgeries when not medically urgent, suggesting that better information and specialist care improve long-term outcomes.

Five pathways that illustrate atypical sex development

The article introduces five examples to show how deviations at different steps can produce diverse outcomes. Each example highlights distinct genetic, gonadal, or hormonal alterations and their consequences for anatomy and fertility.

Congenital adrenal hyperplasia

This DSD affects about one in 16,000 births. The adrenal glands are hyperactive, producing higher-than-normal levels of male hormones. In a baby with two X chromosomes and ovaries, this can result in external genitals that look male, challenging the assumption that sex is dictated by chromosomal sex alone.

Complete androgen insensitivity syndrome (CAIS)

In CAIS, an individual may have XY chromosomes and internal testes that produce testosterone, but the body cannot respond to that testosterone. The lack of response keeps development in a default female trajectory, resulting in female-appearing external genitals at birth. At puberty, secondary sex characteristics such as breasts develop, and many individuals with CAIS are raised as girls and may only be diagnosed after puberty when periods fail to start. CAIS is estimated to affect roughly one to five in 100,000 live-born females.

5-alpha-reductase deficiency

In this condition, a mutation inactivates the enzyme 5-alpha-reductase, which normally converts testosterone to a more potent form before birth. XY infants may be born with genitals read as female and raised as girls, but at puberty the testosterone surge typically masculinizes the body. The condition is rare globally, though certain Dominican communities report relatively high local rates, known there as guevedoces. In some communities, awareness has led to families choosing to raise affected individuals as boys when identified at birth.

Sex chromosomes disorders

Typical male and female patterns involve XX and XY chromosomes, respectively. Variations include Klinefelter syndrome (XXY), Turner syndrome (one X chromosome missing in females), and Swyer syndrome (XY chromosomes with a Y-chromosome mutation that prevents testes development). These conditions illustrate how chromosomal configurations influence gonad development, hormone production, and physical outcomes, sometimes without obvious clinical presentation.

milder differences and non-classic cases

The article notes that some mutations reduce, rather than abolish, enzyme or hormone activity, producing subtler differences that may be underdiagnosed. Non-classic CAH is offered as an example where some enzyme activity remains, yielding less obvious effects yet still affecting development or hormone physiology.

What this tells us about biology and care

Key themes emerge: these conditions are not about sex being meaningless or endlessly fluid, but about showing that sex is a developmental process with multiple steps that can diverge in rare cases. Genetic testing now enables detection of specific mutations behind some DSDS, and patient groups advocate for information and psychological support for patients and families. There is growing emphasis on caution around irreversible childhood surgeries when not medically urgent, as well as the importance of long-term, multidisciplinary care. The piece concludes that DSDS illuminate the complexity of sex designation at birth and challenge simplistic binary narratives, especially when it comes to real-life experiences such as puberty, fertility, and social identity.

Beyond biology: human experience and policy implications

While DSDS do not answer all debates about sex and gender, they underscore that sex is not a single event, but a process that unfolds over a lifetime. The article acknowledges that many people with DSDS will require ongoing hormone therapy, fertility considerations, and sensitive disclosure decisions. It also highlights that the biology of DSDS is part of a larger story about health information, clinical care, psychological support, and patient-centered research, which is essential for improving outcomes and quality of life.