Sexual infantilism or genital infantilism is the syndrome of delayed or arrested development of sexual organs i.e., delayed puberty or absent puberty observed for a number of congenital and endocrine disorders.
Sexual infantilism in boys
Genital infantilism may be be indicative of gonadotropin deficiency resulting from a number of congenital and acquired abnormalities of the central nervous system. Congenital sources of gonadotropin deficiency are described for Kallman syndrome,congenital adrenal hyperplasia, Prader-Willi syndrome, and Biedl-Bardet syndrome. Acquired abnormalities include some brain tumors (e.g., craniopharyngioma, prolactinoma, germinoma, glioma), diseases og hypothalamus, irradiation and trauma. Pubertal delay due to gonadotropin deficiency is treated with testosterone replacement or with HCG 
Abhormal pubertal progressing may be observed for testicular failure, associated with low testosterone levels and high gonadotropin levels, with most common cause being the Klinefelter syndrome. Other possible causes of testicular failure are mumps orchitis, Coxsackievirus B, irradiation, chemotherapy, and trauma. Testicular failure is treated with testosterone replacement.
Sexual infantilism in girls
Observed for gonadotropin deficiency, as in boys and with primary ovarian failure. 
- Francis S. Greenspan, David G. Gardner (2004) Basic & Clinical Endocrinology, ISBN 0071402977, Chapter 15 "Puberty, Section "Delayed Puberty or Absent Puberty" (Sexual Infantilism)", pp. 617-627.
- Marianne J. Legato, ed. (2004) "Principles of Gender-Specific Medicine, Volume 1-2", ISBN 0124409059, p. 22