Can Biological Men Have Xx Chromosomes?

59a26e3b b77b 4956 bffe dd7b1692fcdd 1

The traditional understanding of human genetics dictates that biological males have XY chromosomes, while biological females have XX chromosomes. This binary perspective, however, oversimplifies the complexity of human genetics, which, in rare instances, allows for exceptions. One such exception involves biological males having XX chromosomes, a condition often associated with de la Chapelle Syndrome or XX male syndrome.

Exploring Chromosomal Basics

Chromosomes are thread-like structures made of DNA and proteins, containing the genetic blueprint of an individual. Typically, humans have 46 chromosomes, including two sex chromosomes that determine an individual’s sex: females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The presence of the Y chromosome, specifically the SRY gene on the Y chromosome, is pivotal in determining maleness by triggering the development of male sexual characteristics.

XX Male Syndrome: A Rare Exception

XX male syndrome, also known as de la Chapelle Syndrome, is a rare genetic condition where an individual is genetically female (XX) but phenotypically male. This condition occurs in approximately 1 in 20,000 to 1 in 25,000 newborn males. The syndrome illustrates that the dichotomy of XX=female and XY=male does not always apply.

How Does XX Male Syndrome Occur?

XX male syndrome typically occurs due to the translocation of the SRY gene from the Y chromosome to the X chromosome during gamete formation. This translocation allows the X chromosome carrying the SRY gene to initiate male development, despite the absence of a Y chromosome.

Characteristics and Symptoms

Individuals with XX male syndrome often present male physical characteristics and are usually raised as males. They may have underdeveloped male genitalia, reduced facial and body hair, and may be infertile. The degree of masculinization can vary, and some individuals may not be diagnosed until adolescence or adulthood when fertility issues arise.

Genetic Testing and Diagnosis

Genetic testing is crucial for diagnosing XX male syndrome. Such testing can identify the presence of the SRY gene on one of the X chromosomes. In cases where the SRY gene is not present (which happens in about 10% of XX male individuals), the cause of the male characteristics is less understood and might involve other, less well-characterized genetic factors.

Psychological and Social Implications

The diagnosis of XX male syndrome can have significant psychological and social implications. Individuals with this condition may face challenges related to their identity, fertility concerns, and societal perceptions of gender norms. Support from healthcare providers, genetic counselors, and peer support groups can be instrumental in navigating these challenges.


The phenomenon of biological men having XX chromosomes challenges traditional views of sex and gender, emphasizing the complexity of human genetics. While rare, conditions like XX male syndrome underscore the importance of understanding and recognizing the diversity of human biological development. They also highlight the necessity for sensitive and informed medical and psychological support for individuals with such conditions, fostering a more inclusive and knowledgeable society about the spectrum of human biology.

Vanessa Bergoff

Vanessa is originally from the Ukraine. She has been living in Florida for the last 10 years. She holds a Bachelor's degree in English from the University of Central Florida and a Master's degree in Technical Writing from the University of South Florida. She covers mostly health and health-related issues for the Scientific Origin.