Pituitary Hormone Secretion Profiles in IGSF1 Deficiency Syndrome.
Loss-of-function mutations in immunoglobulin superfamily member 1 (IGSF1) cause an X-linked syndrome of central hypothyroidism, macroorchidism, delayed pubertal testosterone rise, variable prolactin deficiency and variable partial GH deficiency in childhood. The clinical features and gene expression pattern suggest a pivotal role for IGSF1 in the pituitary, but detailed knowledge on pituitary hormone secretion in this syndrome is lacking. We therefore aimed to study the 24-hour pituitary hormone secretion in male patients with IGSF1 deficiency.



We collected blood samples every 10 min for 24 h in eight adult male IGSF1-deficient patients and measured circulating TSH, prolactin and gonadotropins. Deconvolution, modified cosinor and approximate entropy analyses were applied to quantify secretion rates, diurnal rhythmicity and regularity of hormone release. Results were compared to healthy controls matched for age and body mass index.



Compared to healthy controls, IGSF1-deficient patients showed decreased pulsatile secretion of TSH with decreased disorderliness and reduced diurnal variation. Basal and pulsatile secretion of FSH was increased by over 200%, while LH secretion did not differ from healthy controls. We observed a bimodal distribution of prolactin secretion, i.e. severe deficiency in three and increased basal and total secretion in the other five patients.



The altered TSH secretion pattern is consistent with the previously hypothesized defect in thyrotropin-releasing hormone signaling in IGSF1 deficiency. However, the phenotype is more extensive and includes increased FSH secretion without altered LH secretion as well as either undetectable or increased prolactin secretion.
Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, The Netherlands.
Sjoerd D
SD
Joustra
Ferdinand
F
Roelfsema
Erik
E
Endert
Bart E P B
BE
Ballieux
A S Paul
AS
van Trotsenburg
Eric
E
Fliers
Eleonora P M
EP
Corssmit
Daniel J
DJ
Bernard
Wilma
W
Oostdijk
Jan Maarten
JM
Wit
Alberto M
AM
Pereira
Nienke R
NR
Biermasz
D000328:Adult; D000368:Aged; D002940:Circadian Rhythm; D030342:Genetic Diseases, Inborn / Q000378:metabolism*; D006801:Humans; D007136:Immunoglobulins / Q000172:deficiency*; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000172:deficiency*; D008875:Middle Aged; D010265:Paraproteinemias; D011388:Prolactin / Q000378:metabolism; D013972:Thyrotropin / Q000378:metabolism*; D055815:Young Adult
C112314:IGSF1 protein, human; D007136:Immunoglobulins; D008565:Membrane Proteins; D011388:Prolactin; D007986:Luteinizing Hormone; D013972:Thyrotropin