**Core Concept:** Turner syndrome is a genetic disorder characterized by partial or complete absence of one of the two X chromosomes. It primarily affects females, leading to distinctive features, growth abnormalities, and gonadal dysfunction.

**Why the Correct Answer is Right:** Turner syndrome is caused by a genetic abnormality affecting the X chromosome. The syndrome presents with a range of symptoms, including short stature, webbed neck, low-set ears, broad chest, webbed neck, and ovarian dysfunction. Among these features, the absence of gonadal dysfunction is what distinguishes Turner syndrome from other conditions.

**Why Each Wrong Option is Incorrect:**

A. Oligomenorrhea (infrequent menstrual periods), one of the common gonadal dysfunction features in Turner syndrome, makes this option incorrect.

B. Primary amenorrhea (absence of menarche), another common gonadal dysfunction feature in Turner syndrome, is incorrect due to the presence of oligomenorrhea in this condition.

C. Hypothyroidism is a possible complication of Turner syndrome, but it is not a primary feature of the syndrome itself. Therefore, it is incorrect.

D. Hypertension (high blood pressure) is a potential complication in Turner syndrome, but it is not a primary feature of the syndrome. Thus, this option is wrong.

**Clinical Pearl / High-Yield Fact:** Turner syndrome is a crucial topic for medical students, residents, and practicing physicians due to its potential implications for diagnosis, management, and counseling of affected individuals and their families. A thorough understanding of the syndrome and its features is essential for accurate diagnosis and appropriate treatment planning.

**Correct Answer:** B. Primary amenorrhea (absence of menarche) is not a feature of Turner syndrome. Turner syndrome primarily presents with oligomenorrhea (infrequent menstrual periods) and gonadal dysfunction, which can lead to secondary amenorrhea (absence of menstruation) in some cases.