Abstract
We sequenced MKRN3, the major causative gene of central precocious puberty in Western countries, in 24 Japanese or Chinese patients and examined the DNA methylation and copy-number statuses of this gene in 19 patients. We identified no (epi)genetic defects except for one previously reported mutation. These results, together with reports from Korea, indicate that MKRN3 defects are rare in Asian populations. The ethnic differences likely reflect Western country-specific founder mutations and the rarity of de novo mutations.
Central precocious puberty (CPP) is a rare multifactorial disorder caused by an age-inappropriate secretion of the gonadotropin-releasing hormone from the hypothalamus1. CPP can occur as a result of monogenic mutations, although it is frequently associated with brain lesions, such as tumor and injury1. Thus far, a few genes, including KISS1R, KISS1, PROKR2, and NR0B1, have been reported as causative genes for CPP1,2,3. In addition, two imprinted genes, MKRN3 and DLK1, have recently been implicated in the development of CPP4,5. Mutations in MKRN3 and DLK1 cause CPP when they reside on paternally derived alleles. The association between epigenetic defects of MKRN3 or DLK1 and CPP has yet to be determined.
Previous studies in Western countries have identified pathogenic MKRN3 mutations in 9–46% of familial cases and 3–20% of sporadic cases with CPP (Table 1), indicating that these mutations play an important role in the etiology of CPP. In contrast, Lee et al. identified pathogenic MKRN3 mutations only in one of 260 Korean patients with CPP6. Likewise, Jeong et al. reported the lack of pathogenic MKRN3 mutations in 26 Korean patients with familial CPP7. These data indicate that there may be an ethnic difference in the frequency of MKRN3 mutations in CPP patients. However, MKRN3 mutation analyses have rarely been performed in Asian countries other than Korea, except for our previous study in which MKRN3 mutations were identified in one of 15 Japanese patients8. Moreover, since Lee et al.6 and Jeong et al.7 did not examine DNA methylation defects or copy-number alterations of MKRN3, these abnormalities may be hidden in their patients.
Here we searched for genetic and epigenetic defects of MKRN3 in Japanese and Chinese patients with etiology-unknown CPP. Nucleotide substitutions were analyzed in 24 (22 Japanese and 2 Chinese) patients, whereas DNA methylation defects and copy-number alterations were examined only in 19 Japanese patients for whom we could obtain a sufficient amount of genomic DNA. This study was approved by the Institutional Review Board Committee of the National Research Institute for Child Health and Development and performed after obtaining written informed consent. All patients satisfied the following criteria: (i) early pubertal onset (in boys, testicular enlargement before 9 years of age, pubic hair before 10 years of age, or axillary hair/voice change before 11 years of age; in girls, breast budding before 7.5 years of age, pubic hair before 8 years of age, or menarche before 10.5 years of age); (ii) increased blood levels of gonadotropin and sex hormone; (iii) normal findings in brain magnetic resonance imaging; and (iv) no pathogenic mutations in DLK1, KISS1R, KISS1, PROKR2, or NR0B1. Patients with congenital malformation syndromes and those with chronic disorders that may affect hormone secretion were excluded from this study. Patients had no apparent family history of early puberty.
First, we searched for MKRN3 sequence variations in 24 patients. Thirteen patients were previously subjected to whole-exome sequencing using a Nextera Rapid Capture Exome Kit (HiSeq SBS Kit v4-HS Illumina, San Diego, CA, USA) and a HiSeq 2500 sequencer (Illumina)8. The remaining 11 patients were first examined in the present study; targeted sequencing of their DNA was performed for 148 genes using the HaloPlex HS Target Enrichment System (Design ID 40350-1451214604; Agilent Technologies, Palo Alto, CA, USA) and a MiSeq sequencer (Illumina). Sequence data of the 24 patients were analyzed as described previously3. We focused on nonsynonymous variants in the coding region and intronic substitutions affecting splice sites of MKRN3. Variants whose frequency in the Japanese general population [the ExAC browser (http://exac.broadinstitute.org/) and the Human Genetic Variation Browser (http://www.hgvd.genome.med.kyoto-u.ac.jp/)] is more than 1% were excluded as polymorphisms.
Next, we conducted DNA methylation and copy-number analyses for 19 patients. The DNA methylation status of seven CpG sites at the MKRN3 locus was examined by pyrosequencing using a previously described method9. Copy-number alterations of MKRN3 were analyzed by real-time PCR using a TaqMan Copy Number Assay Kit (MKRN3, Hs02079798; internal control, 440332; ThermoFisher Scientific, Tokyo, Japan) according to the manufacturer’s instructions.
Consequently, rare nucleotide substitutions of MKRN3 were not detected in the 24 patients except for one female patient with c.684dupA (p.Glu229Argfs*3), who has been reported previously8. Moreover, DNA methylation statuses were comparable between the patients and control individuals (Fig. 1). Similarly, copy-number analysis identified no deletions or duplications of MKRN3 in all patients examined.
The results of this study expand the prior notion of Lee et al.6 and Jeong et al.7 to suggest that genetic and epigenetic defects in MKRN3 are relatively rare in Asian CPP patients. Although underlying factors of the ethnic difference in the frequency of MKRN3 mutations remain to be determined, the relatively high frequency in Western countries possibly reflects the presence of multiple founder mutations. Indeed, c.482delC (p.Pro161Argfs*10), c.482dupC (p.Ala162Glyfs*15), c.802_803delAT (p.Met268Valfs*23), c.982C > T (p.Arg328Cys), and c.1095G > T (p.Arg365Ser) have been repeatedly identified in patients from these countries (Table 1). In this regard, since there have been no reports of de novo MKRN3 mutations in CPP patients, the de novo occurrence of MKRN3 substitutions seems to be an exceptional event. Moreover, our data suggest that DNA methylation defects and copy-number alterations of MKRN3 play only a minor role in the development of CPP, if at all.
In conclusion, the results of this study, together with two reports from Korea6,7, indicate that (epi)genetic defects of MKRN3 represent only a minor cause of CPP in Asian populations. The presence of multiple founder mutations in Western countries as well as the rarity of de novo occurrences of intragenic nucleotide substitutions likely underlies the ethnic differences in the frequency of MKRN3 mutations in CPP cases.
HGV database
The relevant data from this Data Report are hosted at the Human Genome Variation Database at https://doi.org/10.6084/m9.figshare.hgv.2525
References
Latronico, A. C., Brito, V. N. & Carel, J. C. Causes, diagnosis, and treatment of central precocious puberty. Lancet Diabetes Endocrinol. 4, 265–274 (2016).
Fukami, M. et al. Paradoxical gain-of-function mutant of the G-protein-coupled receptor PROKR2 promotes early puberty. J. Cell. Mol. Med. 21, 2623–2626 (2017).
Shima, H. et al. NR0B1 frameshift mutation in a boy with idiopathic central precocious puberty. Sex. Dev. 10, 205–209 (2016).
Abreu, A. P. et al. Central precocious puberty caused by mutations in the imprinted gene MKRN3. N. Engl. J. Med. 368, 2467–2475 (2013).
Dauber, A. et al. Paternally inherited DLK1 deletion associated with familial central precocious puberty. J. Clin. Endocrinol. Metab. 102, 1557–1567 (2017).
Lee, H. S. et al. Low frequency of MKRN3 mutations in central precocious puberty among Korean girls. Horm. Metab. Res. 2, 118–122 (2016).
Jeong, H. R., Lee, H. S. & Hwang, J. S. Makorin ring finger 3 gene analysis in Koreans with familial precocious puberty. J. Pediatr. Endocrinol. Metab. 30, 1197–1201 (2017).
Nishioka, J. et al. The first Japanese case of central precocious puberty with a novel MKRN3 mutation. Hum. Genome Var. 4, 17017 (2017).
Kagami, M. et al. Epimutations of the IG-DMR and the MEG3-DMR at the 14q32.2 imprinted region in two patients with Silver-Russell syndrome-compatible phenotype. Eur. J. Hum. Genet. 23, 1062–1067 (2015).
Schreiner, F., Gohlke, B., Hamm, M., Korsch, E. & Woelfle, J. MKRN3 mutations in familial central precocious puberty. Horm. Res. Paediatr. 82, 122–126 (2014).
Bessa, D. S. et al. High frequency of MKRN3 mutations in male central precocious puberty previously classified as idiopathic. Neuroendocrinology 105, 17–25 (2017).
Simon, D. et al. Mutations in the maternally imprinted gene MKRN3 are common in familial central precocious puberty. Eur. J. Endocrinol. 174, 1–8 (2016).
Grandone, A. et al. Molecular screening of MKRN3, DLK1, and KCNK9 genes in girls with idiopathic central precocious puberty. Horm. Res. Paediatr. 88, 194–200 (2017).
Simsek, E., Demiral, M., Ceylaner, S. & Kırel, B. Two frameshift mutations in MKRN3 in Turkish patients with familial central precocious puberty. Horm. Res. Paediatr. 87, 405–411 (2017).
Aycan, Z. et al. Investigation of MKRN3 mutation in patients with familial central precocious puberty. J. Clin. Res. Pediatr. Endocrinol. 10, 223–229 (2018).
Ortiz-Cabrera, N. V. et al. Clinical exome sequencing reveals MKRN3 pathogenic variants in familial and nonfamilial idiopathic central precocious puberty. Horm. Res. Paediatr. 87, 88–94 (2017).
Macedo, D. B. et al. Central precocious puberty that appears to be sporadic caused by paternally inherited mutations in the imprinted gene makorin ring finger 3. J. Clin. Endocrinol. Metab. 99, E1097–E1103 (2014).
Dimitrova-Mladenova, M. S. et al. Males with paternally inherited MKRN3 mutations may be asymptomatic. J. Pediatr. 179, 263–265 (2016).
Känsäkoski, J., Raivio, T., Juul, A. & Tommiska, J. A missense mutation in MKRN3 in a Danish girl with central precocious puberty and her brother with early puberty. Pediatr. Res. 78, 709–711 (2015).
Acknowledgements
This study was supported by the Grant-in-Aids for Scientific Research on Innovative Areas (17H06428) and Grant-in-Aid for Early-Career Scientists (18K16249) from JSPS and by grants from AMED, the National Center for Child Health and Development, and the Takeda Science Foundation.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of interest
The authors declare that they have no conflict of interest.
Additional information
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
About this article
Cite this article
Suzuki, E., Shima, H., Kagami, M. et al. (Epi)genetic defects of MKRN3 are rare in Asian patients with central precocious puberty. Hum Genome Var 6, 7 (2019). https://doi.org/10.1038/s41439-019-0039-9
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41439-019-0039-9
This article is cited by
-
MKRN3 circulating levels in girls with central precocious puberty caused by MKRN3 gene mutations
Journal of Endocrinological Investigation (2023)