The incidence of an extreme form of early-onset puberty triggered by the brain is not increasing in boys, according to new research by NIEHS scientists and their collaborators. The condition, known as central precocious puberty (CPP), is so named because a medical condition is often the cause, and children reach puberty especially early — before age nine.

The findings, published June 27 in the journal PLoS One, also suggested that in some cases, genetic testing may be more appropriate than brain imaging as the first step in identifying the cause of CPP.

A focus on boys

Shaw, a Lasker Clinical Research Scholar, also studies puberty in girls (see sidebar). (Photo courtesy of Steve McCaw)

'There has been a wealth of research and media attention devoted to earlier pubertal development among U.S. girls, but where are the boys?' said senior study author Natalie Shaw, M.D., head of the NIEHS Pediatric Neuroendocrinology Group. 'To our knowledge, this is the first study of boys with extreme early puberty in the U.S.'

Historically, pubertal onset in boys has occurred at around 11 and a half years old. However, large-scale observational studies in the U.S., Europe, and Asia now suggest that puberty may be occurring earlier in boys, similar to the pattern observed in girls.

Until recently, scientists did not know whether there has also been an increase in male CPP. Diagnosing CPP is particularly important because the condition is sometimes caused by a brain tumor.

Puberty as early as age 7

Shaw, a former fellow and attending physician at Boston Children’s Hospital (BCH), and her collaborators at BCH performed a medical chart review of 1,005 boys. The children were seen between 2001 and 2010 by BCH pediatric staff who specialize in hormonal disorders. Fifty of the boys were diagnosed with CPP and entered puberty at an average age of 7.3 years.

Consistent with past research, in 64 percent of the cases studied, CPP was caused by a medical issue originating in the nervous system. Neurofibromatosis, a genetic disorder that causes tumors to form in nervous system tissues, was the cause in this group far more often than were brain tumors.

Importantly, no cause was identified in the remaining 36 percent of patients. Some patients reported a family history of early puberty, suggesting a possible genetic origin. Other scientists reported changes in a gene called MKRN3 in families with early puberty occurring across multiple generations.

'We propose that genetic testing, particularly for MKRN3, should be done before brain imaging when diagnosing CPP in some boys,' Shaw said.

Citation: Topor LS, Bowerman K, Machan JT, Gilbert C, Kangarloo T, Shaw ND. 2018. Central precocious puberty in Boston boys: a 10-year single center experience. PLoS One 13(6):e0199019.

(Janelle Weaver, Ph.D., is a contract writer for the NIEHS Office of Communications and Public Liaison.)