A person's sex can vary from typical male or female in terms of chromosomes, anatomy or hormones. This section discusses the genetic causes of the most common variations in sex development and their biological implications, focusing on those that are obvious at birth.




Intersex and DSD: What's the difference?

Terminology in this area continues to be a subject of debate and contention.

One term that is commonly applied to developmental variations in sexual anatomy is "intersex". This term became popular in the medical profession in the mid-20th century.

Then, in 2005, an international group of doctors, scientists and patient group representatives met in Chicago to discuss management and possible classifications for this range of conditions. This group suggested a new term "Disorders of Sex Development" (DSD) to define congenital conditions in which anatomical, chromosomal or gonadal sex is atypical. This terminology has since been adopted by the international classification of diseases (ICD).

But many intersex advocacy groups objected to this term, and many still do, expressing views that include:

  • The Chicago meeting did not include enough intersex people to support the development of an inclusive terminology
  • Variations in sex development are not disorders at all, but simply a reflection of a continuum that exists in the natural world, similar to height, eye colour, or other variables
  • The term DSD can be unhelpful and even damaging, because using the term "disorder" can have negative psychological impacts and create unnecessary stigma.

Other advocacy groups welcomed the term 'DSD' for reasons that include:

  • It is considered helpful for those seeking access to insurance and medical assistance, as with other medically defined disorders
  • Some find it helpful to describe their condition as a legitimate and recognised disorder with a medical name and a defined genetic cause
  • The term 'intersex' implies some mixing or indeterminateness of male and female characteristics, and does not cater well for those whose biological sex is closely aligned to typical male or female.

Those promoting the term 'intersex' have tended to be more publicly prominent, and 'intersex' is a term that is easily understood by most people. Hence, the term 'intersex' has gained traction in public and political arenas.

For the medical profession, and the scientific community, 'DSD' terminology and the classification system attached to it allows individual conditions to be referred to more accurately (47,XXY DSD, 46,XY DSD and so on). This degree of accuracy is important when trying to learn more about outcomes related to a given variation (for example malignancy risk in a certain DSD subtype).

Some have tried to broker a compromise, either by suggesting that 'DSD' can be used to stand for "Difference in Sex Development" or "Diversity of Sex Development". Others suggest that "Variations of Sex Development" ('VSD') may be a useful term to avoid controversy.

In summary, the current situation sees a mixture of terms in use.


What term should I use?

What term to use may depend on:

  • The context - who is communicating with whom. Medical practioners, for example, tend to use the term 'DSD' among themselves, but switch to using 'intersex' if they consider that to be the preferred or better understood term when dealing with affected individuals, parents, politicians or public. For conversations at an individual level, it is helpful to ask about preferred terminology and to use terms that a person is comfortable with in relation to their own variation.
  • The subject - what exact condition is being referred to. For example, some conditions may involve a degree of sexual ambiguity or atypical sex charateristics, without involving any specific pathology: in such situations the term 'intersex' may be a useful alternative to 'DSD'. Other conditions may be pimarily characterised by some metabolic, morphologic or functional issue that impacts negatively on quality of life and requires or would benefit from medical intervention: the term 'DSD' may be more appropriate here.

Bearing in mind the broad range of conditions involved, coming up with one single 'umbrella' term that adequately describes all of them is arguably not possible.

On this website, readers will frequently encounter the term 'DSD', which we have found to be a precise and workable professional term from a scientific and medical perspective. However, we also choose to use other terminology (such as atypical sex development, variant sex development, and so on) in many places, depending on the subject.


Classifying variation in sex development

Atypical sex development covers a very broad spectrum of conditions. How should these be classified, at least for the purposes of presenting them in some logical order on this website?

One might classify sex variations according to the type of gene and the biological process affected, for example disruptions of Sertoli cell differentiation, disruptions of gonad formation, hormonal defects, and so on.

Alternatively, one might make the distinction between chromosomal anomalies, conditions affecting XX individuals and those affecting XY individuals.

Or, one may classify conditions according to whether reproductive organs form atypically, incompletely, or excessively.

We consider that this website will most likely be used by parents or families of newborn children who do not have the typical appearance of males or females. For that reason, we have organised the information based on when the visible signs are usually first noticed, rather than presupposing any knowledge of what the underlying cause might be.


Information provided on this website

The material provided here reflects a combination of our own research data, published research findings from the international scientific community, and information from other publicly available resources. It is intended as a description of the current state of knowledge, not a source of medical advice. Readers are advised to seek the services of a qualified medical practitioner when considering any diagnostic or treatment options. See Disclaimer.



Last updated: 7 August 2021 PK

Edit history: Author P. Koopman 5/2011; revised PK 9/2012, 5/2013, 10/2013, 3/2014, 7/2015