Mutations in prokineticin 2 and prokineticin receptor 2 genes in human gonadotrophin-releasing hormone deficiency: molecular genetics and clinical spectrum.
BACKGROUND
Mice deficient in prokineticin 2(PROK2) and prokineticin receptor2 (PROKR2) exhibit variable olfactory bulb dysgenesis and GnRH neuronal migration defects reminiscent of human GnRH deficiency.


OBJECTIVE
We aimed to screen a large cohort of patients with Kallmann syndrome (KS) and normosmic idiopathic hypogonadotropic hypogonadism (IHH) for mutations in PROK2/PROKR2, evaluate their prevalence, define the genotype/phenotype relationship, and assess the functionality of these mutant alleles in vitro.


METHODS
Sequencing of the PROK2 and PROKR2 genes was performed in 170 KS patients and 154 nIHH. Mutations were examined using early growth response 1-luciferase assays in HEK 293 cells and aequorin assays in Chinese hamster ovary cells.


RESULTS
Four heterozygous and one homozygous PROK2 mutation (p.A24P, p.C34Y, p.I50M, p.R73C, and p.I55fsX1) were identified in five probands. Four probands had KS and one nIHH, and all had absent puberty. Each mutant peptide impaired receptor signaling in vitro except the I50M. There were 11 patients who carried a heterozygous PROKR2 mutation (p.R85C, p.Y113H, p.V115M, p.R164Q, p.L173R, p.W178S, p.S188L, p.R248Q, p.V331M, and p.R357W). Among them, six had KS, four nIHH, and one KS proband carried both a PROKR2 (p.V115M) and PROK2 (p.A24P) mutation. Reproductive phenotypes ranged from absent to partial puberty to complete reversal of GnRH deficiency after discontinuation of therapy. All mutant alleles appear to decrease intracellular calcium mobilization; seven exhibited decreased MAPK signaling, and six displayed decreased receptor expression. Nonreproductive phenotypes included fibrous dysplasia, sleep disorder, synkinesia, and epilepsy. Finally, considerable variability was evident in family members with the same mutation, including asymptomatic carriers.


CONCLUSIONS
Loss-of-function mutations in PROK2 and PROKR2 underlie both KS and nIHH.
Reproductive Endocrine Unit of the Department of Medicine, Harvard Reproductive Endocrine Sciences Center, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
Lindsay W
LW
Cole
Yisrael
Y
Sidis
ChengKang
C
Zhang
Richard
R
Quinton
Lacey
L
Plummer
Duarte
D
Pignatelli
Virginia A
VA
Hughes
Andrew A
AA
Dwyer
Taneli
T
Raivio
Frances J
FJ
Hayes
Stephanie B
SB
Seminara
Celine
C
Huot
Nathalie
N
Alos
Phyllis
P
Speiser
Akira
A
Takeshita
Guy
G
Van Vliet
Simon
S
Pearce
William F
WF
Crowley
Qun-Yong
QY
Zhou
Nelly
N
Pitteloud
D000293:Adolescent; D000331:Aequorin / Q000235:genetics; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004252:DNA Mutational Analysis; D005260:Female; D005768:Gastrointestinal Hormones / Q000235:genetics*; D005787:Gene Frequency; D018740:Genetic Heterogeneity; D005838:Genotype; D007987:Gonadotropin-Releasing Hormone / Q000172:deficiency*; D006801:Humans; D007006:Hypogonadism / Q000235:genetics*; D017436:Kallmann Syndrome / Q000235:genetics; D008297:Male; D008954:Models, Biological; D020125:Mutation, Missense; D009479:Neuropeptides / Q000235:genetics*; D010375:Pedigree; D043562:Receptors, G-Protein-Coupled / Q000235:genetics*; D018000:Receptors, Peptide / Q000235:genetics*; D014162:Transfection
D005768:Gastrointestinal Hormones; D009479:Neuropeptides; C423608:PROK2 protein, human; C470838:PROKR2 protein, human; D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide; D007987:Gonadotropin-Releasing Hormone; D000331:Aequorin