Genetic Syndromes Presenting in Childhood Affecting Gonadotropin Function

Abstract

This chapter will focus on two genetic syndromes affecting gonadotropin function that typically present in childhood, Klinefelter syndrome, and testotoxicosis.

Klinefelter syndrome (47,XXY) is the most common sex chromosome aneuploidy with a prevalence of 1 in 450–500 male births. Unless detected by prenatal screening or prenatal diagnosis, this chromosome variation diagnosis is frequently missed in children. Physical, neurocognitive, and psychosocial phenotypes of boys with 47,XXY are extremely variable, making a typical case difficult to characterize. Health care needs of boys born with 47,XXY are complex including the need for monitoring growth, pubertal development, optimization of reproductive capacity, bone health, and acknowledgement of physical symptoms such as fatigue, hypotonic muscle strength, tremors, tics, and pain. Physical health risks associated with 47,XXY include: metabolic syndrome, Type II diabetes, cardiovascular disease, immunological issues, bone loss, and certain types of malignancies. Boys with 47,XXY frequently show executive function issues, language-based learning difficulties, problems with communication, and struggles with behavior that contribute to stressors for the boys as well as for their families. Psychosocial manifestations of these stressors include low self-esteem, increased risk for depression, difficulties maintaining personal relationships, and adverse quality of life. There is a general lack of awareness in the health care community about the complexities of care required for families who have sons with 47,XXY. Since puberty is a sentinel time for diagnosing and monitoring hypogonadism, families often depend on professionals in the specialty of endocrinology to address their many concerns. Families seeking anticipatory guidance about how 47,XXY will influence the growth and development of their sons often look to the specialty of endocrinology to help them navigate a health care environment that is confusing to them. This chapter will describe the physical, neurocognitive, and psychosocial phenotype of 47,XXY in childhood and provide suggestions for endocrine-related health surveillance for advanced practice nurses (APRN). APRNs in endocrinology practice are perfectly positioned to assess, coordinate, and provide family-centered navigation for health surveillance according to child’s level of development.

Testotoxicosis or familial male-limited precocious puberty is a rare dominant form of gonadotropin-independent precocious puberty caused by constitutively activating mutations of the luteinizing hormone receptor. Affected males present premature and progressive virilization associated with accelerated growth and advanced bone age between 2 and 4 years of age. Hormonal profile is characterized by elevated testosterone levels, despite prepubertal levels of luteinizing hormone. Treatment typically consists of reducing hyperandrogenism with ketoconazole or a combination of anti-androgens and aromatase inhibitors.