Medical school taught us that certain chromosomal and biochemical differences exist that result in genitalia at birth that is not clearly a clitoris or a penis. We know that the designation of biological sex can be more complex than what is indicated by visible genitalia. Some of us might recall from first-year biochemistry that the most common cause of atypical genitalia at birth is congenital adrenal hyperplasia (CAH). But CAH is only one of many causes of biological sex that does not fall into the binary of male or female, and the differential is long.

Not all differences of sexual development (DSD), also termed disorders of sexual development, result in genitalia demonstrated at birth that deviates from standard male or female appearances. Some require anatomic surveys or chromosomal analysis to determine an accurate diagnosis. Some DSD are not diagnosed until puberty or later. And the likelihood of each diagnosis on this long differential also varies widely. CAH, the most common cause of "ambiguous" genitalia, affects one in 13,000 live births. Klinefelter syndrome, in which an individual has XXY chromosomes and does not typically receive a diagnosis until puberty, is much more common at 1 in 1,000.

Individuals can have atypical genitalia at birth, both male and female reproductive organs, differences in enzymatic activation of puberty that leads to secondary sex characteristics different from sex assigned at birth, mosaic genetics where some chromosomes are labeled XY and others XX, or several other variations leading to a biological sex that is not male or female. These variations are grouped as intersex conditions or DSD.

(The historical terms "hermaphrodite" and "pseudo-hermaphrodite" are outdated, pejorative, stigmatizing and no longer used in medical literature or research.)

Biological sex is assigned at birth as male, female or intersex based on external and internal reproductive anatomy and/or genetic testing. Despite longstanding medical knowledge of intersex conditions, the first birth certificates to accurately denote someone's sex as intersex were not issued until 2016 in New York City and in 2018 in Colorado.

In contrast to biological sex, gender identity is an individual's inner knowledge of who they are with respect to their gender. Just as biological sex is not a binary, gender identity is not a binary. Individuals may identify their gender as man, woman, or something else.  

Individuals define their gender for themselves. Some people do not identify their gender as man or woman, and some may define their gender differently than their sex assigned at birth.

Gender is a social construct. In the United States, gender has historically been defined as man or woman. However, some cultures have long recognized gender identities outside this binary. "Fa'afafine" in Samoan society, "two spirit" in indigenous North American culture and "hijra" in South Asia  are three such examples. In Western culture, individuals who identify their gender as different than their sex assigned at birth are commonly grouped under the umbrella term "transgender," abbreviated "trans." Gender identity that is the same as sex assigned at birth is referred to as "cisgender."

According to the American Academy of Pediatrics, gender identity develops as early as 2 years of age. Children have a consistent and persistent understanding of their own gender identity by age 4. It is common for children to experiment with gender expression by wearing the clothes of the opposite gender or by taking on culturally determined gender roles different from their identity during play. Gender roles and gender expression are distinct from gender identity.

Gender expression may be feminine, masculine or androgynous and may change depending on where you are going and who you are with. Gender roles or norms are cultural constructs of what we expect of men or women, such as who works full time, who does the cooking, who we assume to be flying the plane or staying home with the baby. Every time a female physician is assumed to be a nurse, she is reminded of gender norms.

Some transgender people may be diagnosed with gender dysphoria. According to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, diagnosis of gender dysphoria requires six months' duration of the gender identity and at least two of the following:

• "A marked incongruence between one's experienced/expressed gender and primary and/or secondary sex characteristics
  
• A strong desire to be rid of one's primary and/or secondary sex characteristics
  
• A strong desire for the primary and/or secondary sex characteristics of the other gender
  
• A strong desire to be of the other gender
  
• A strong desire to be treated as the other gender
  
• A strong conviction that one has the typical feelings and reactions of the other gender."

In children, the diagnosis of gender dysphoria also includes six months of significant distress relating to the gender identity.

Some patients who identify as transgender may desire to medically transition using gender-affirming hormones. In the LGBT Curriculum Guideline, the AAFP recommends family physicians be trained in this area of medicine during residency. This guideline also recognizes the difference between biological sex and gender identity.

An HHS memo regarding these issues was recently brought to light by The New York Times. The memo calls for the definition of sex under Title IX to be made based "on a biological basis that is clear, grounded in science, objective and administrable." The memo goes on to state that "The sex listed on a person's birth certificate, as originally issued, shall constitute definitive proof of a person's sex unless rebutted by reliable genetic evidence."

The vast majority of states do not allow designation of intersex on birth certificates. Only male or female options exist. Additionally, this new definition would remove protection from discrimination for more than 1 million transgender Americans.

In 2016, under the Obama administration, Title IX coverage was expanded to include "discrimination based on a student's gender identity, including discrimination based on a student's transgender status." Title IX is a statue within the Education Amendments of 1972 that "protects people from discrimination based on sex in education programs or activities that receive federal financial assistance." Title IX protects Americans at federally funded programs from discrimination on the basis of sex in employment, admissions, discipline, financial assistance, harassment and more.

This Obama-era protection was most publicized for allowing transgender students to use the bathroom consistent with their gender identity. Most people do not think twice about our trips to the bathroom. This universal part of anyone's day -- the ability to use the bathroom of one's gender identity -- was only part of the protection extended to transgender Americans by expansion of the Title IX definition to include gender identity. It made discrimination against transgender people illegal in institutions that receive federal dollars.

The HHS memo has not yet developed into a proposed rule, but one is expected. A policy inaccurately defining biological sex as a binary and incorrectly assuming sex and gender identity are the same would open intersex and transgender people to increased discrimination and bias. Discrimination is one of the most common barriers to accessing health care for transgender Americans.

The AAFP LGBT Curriculum Guideline discusses the importance of exploring one's own bias, responding to witnessed bias toward patients and colleagues, and advocating for LGBT patients. It calls for future family physicians to actively work to lessen bias.

Recognizing that the greatest barrier to health care access for transgender people is lack of knowledgeable providers, family physicians can take the lead in educating their home institutions. The National LGBT Health Education Center's free online module "Improving Health Care for Transgender People" is a great place to start.

After the administration's memo was reported, one of my patients who is transgender said to me, "They are trying to erase us." The dramatic increase in calls received by Trans Lifeline, a suicide hotline for transgender people, echoed her distress.

Transgender and intersex people are people. They deserve recognition and protection from discrimination. To make sure discrimination in medicine against trans people is not made legal, visit Protect Trans Health.

As family physicians, we cannot let this medically inaccurate redefining of sex further marginalize our patients. We must address our own bias, be proactive about educating ourselves and our communities, and take a stand in support of our transgender and intersex patients, loved ones and fellow Americans.

Natalie Hinchcliffe, D.O., loves teaching residents, advocating for her patients and addressing stigmas in medicine. She is passionate about providing care for lesbian, gay, bisexual, transgender and queer patients; HIV primary care; and reproductive health and family planning services where access to such care is limited. She practices in Ohio.