A 15-year-old girl is brought to the office by her mother due to concerns that her daughter has not had a menstrual period. The patient was born at 36 weeks gestation but has had no developmental delay. She is doing well in school and plays on the tennis team. The patient is healthy and takes no medications. She is not sexually active and does not use tobacco, alcohol, or illicit drugs. Family history is significant for a maternal aunt with primary infertility and a maternal grandmother with ovarian cancer. Height is 174 cm (5 ft 7 in), and weight is 63 kg (138.9 lb). Vital signs are normal. There is no acne or excessive hair growth. Breast development is sexual maturity rating (Tanner) stage 5. There is scant axillary and pubic hair. On pelvic examination, the external genitalia appear normal and speculum examination shows a blind vaginal pouch. The uterus, cervix, and ovaries are absent on bimanual examination. Karyotype analysis of this patient is most likely to show which of the following?

Question

A 15-year-old girl is brought to the office by her mother due to concerns that her daughter has not had a menstrual period.  The patient was born at 36 weeks gestation but has had no developmental delay.  She is doing well in school and plays on the tennis team.  The patient is healthy and takes no medications.  She is not sexually active and does not use tobacco, alcohol, or illicit drugs.  Family history is significant for a maternal aunt with primary infertility and a maternal grandmother with ovarian cancer.  Height is 174 cm (5 ft 7 in), and weight is 63 kg (138.9 lb).  Vital signs are normal.  There is no acne or excessive hair growth.  Breast development is sexual maturity rating (Tanner) stage 5.  There is scant axillary and pubic hair.  On pelvic examination, the external genitalia appear normal and speculum examination shows a blind vaginal pouch.  The uterus, cervix, and ovaries are absent on bimanual examination.  Karyotype analysis of this patient is most likely to show which of the following?

Quizplus · Accepted Answer

11ec25c8_d9a5_c75d_bc81_176b4681d8f3_MD0003_00 This patient has androgen insensitivity syndrome (AIS), an X-linked recessive condition in which genotypically male (46,XY karyotype) patients have nonfunctioning androgen receptors that cause peripheral androgen resistance. These patients have functioning testes, resulting in the characteristic fetal and pubertal development associated with AIS. During fetal AIS development, the testes produce anti-Müllerian hormone (AMH) and testosterone. AMH acts on Müllerian structures (ie, uterus, upper one-third of vagina) and causes their regression. In contrast, testosterone has no activity on peripheral tissues, and male external genitalia (eg, penis, prostate) do not develop, defaulting to female external genitalia (eg, lower two-thirds of vagina). Therefore, these patients appear phenotypically female at birth. Pubertal patients with AIS typically have primary amenorrhea (ie, no uterus and a blind vaginal pouch) and some secondary sexual characteristic development. Although the testes produce normal male pubertal-range testosterone levels, patients have no acne and minimal to no axillary and pubic hair due to peripheral androgen resistance. However, the increased testosterone is aromatized to estrogen and results in breast development and tall stature. patients with AIS (Choice A) Patients with Turner syndrome (45,X) often have primary amenorrhea due to small, nonfunctional ovaries (ie, streak ovaries). They also typically have short stature and minimal breast development (ie, "shield chest"), making this diagnosis unlikely in this patient. (Choice B) Müllerian agenesis (Mayer-Rokitansky-Küster-Hauser syndrome [46,XX]) is the absence of the uterus, cervix, and upper one-third of the vagina. Patients with this disorder have primary amenorrhea and breast development. In contrast to this patient, those with Müllerian agenesis have ovaries as well as normal axillary and pubic hair development. (Choice D) Patients with Klinefelter syndrome (47,XXY) can have breast development (ie, gynecomastia), tall stature, and minimal body hair. However, they have a penis and small, descended testes (ie, hypogonadism), making this diagnosis unlikely in this patient. Klinefelter syndrome (Choice E) Patients with a 47,XYY karyotype appear phenotypically male and develop nodulocystic acne at puberty. They require neurodevelopmental evaluation due to the increased incidence of learning disabilities, behavioral problems, and developmental delay. Educational objective: Androgen insensitivity syndrome is the result of nonfunctioning androgen receptors that lead to peripheral androgen resistance. These patients are genotypically male (46,XY) but appear phenotypically female with breast development and female external genitalia; however, they have no female internal genitalia (eg, uterus, ovaries) and minimal to no axillary or pubic hair. References: Androgen insensitivity syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/22698698) Androgen insensitivity syndrome: a review. (http://www.ncbi.nlm.nih.gov/pubmed/29768628) Molecular biology of androgen insensitivity. (http://www.ncbi.nlm.nih.gov/pubmed/21871529)

A 15-Year-Old Girl Is Brought to the Office by Her