Kallmann syndrome combines anosmia, related to defective olfactory bulb morphogenesis, and hypogonadism due to gonadotropin-releasing hormone deficiency. Loss-of-function mutations in KAL1 and FGFR1 underlie the X chromosome-linked form and an autosomal dominant form of the disease, respectively. Mutations in these genes, however, only account for approximately 20% of all Kallmann syndrome cases. In a cohort of 192 patients we took a candidate gene strategy and identified ten and four different point mutations in the genes encoding the G protein-coupled prokineticin receptor-2 (PROKR2) and one of its ligands, prokineticin-2 (PROK2), respectively. The mutations in PROK2 were detected in the heterozygous state, whereas PROKR2 mutations were found in the heterozygous, homozygous, or compound heterozygous state. In addition, one of the patients heterozygous for a PROKR2 mutation was also carrying a missense mutation in KAL1, thus indicating a possible digenic inheritance of the disease in this individual. These findings reveal that insufficient prokineticin-signaling through PROKR2 leads to abnormal development of the olfactory system and reproductive axis in man. They also shed new light on the complex genetic transmission of Kallmann syndrome.

We have studied nine patients aged 1 month to 16 years with 46, XX karyotypes and testicular tissue. Some of these patients were followed through puberty. Phenotypically, two presented normal and seven abnormal external genitalia (AG). Among this latter group, four showed hypospadias and three true hermaphroditism (TH). The endocrine data were similar in all three groups: testosterone levels were within normal limits during puberty, decreasing in adulthood; gonadotrophin levels were above the control values at mid puberty. Histologies of the two sub groups of AG patients were identical up to 5 years of age and presented differences when compared with controls, regardless of the ovarian part of the ovotestis. However, in patients older than 8 years, germ cells disappeared and dysgenesis became obvious. In one patient, the ovarian zone of the gonad was detected only after complete serial sections of the removed gonad were examined. Southern blot analysis with Y-DNA probes displayed Y-specific material for the classic 46 XX males and a lack of such sequences for all patients with AG and TH. Based on these findings, we postulate that 46, XX males with AG and 46, XX TH may represent alternative manifestations of the same genetic defect. These data together with those concerning familial cases of 46, XX males with AG and 46, XX TH suggest an autosomally (or pseudoautosomally) determined mechanism.

We observed four families with loss of function mutations of the TSH receptor gene. One patient had a homozygous Pro162 Ala substitution. The three other were compound heterozygotes: 1) Gln324-->Stop and Asp410 Asn2), Cys41 Ser and Phe525 Leu, 3) Cys390 Trp and Trp546-->Stop. In all patients, the plasma TSH concentration was increased, whereas T3 and T4 concentrations were normal. The TSH levels were normal in the heterozygous parents. These results confirmed the recessive character of TSH receptor defects. Expression of the various mutated receptors in transfected COS-7 cells demonstrated the impairment of their function. We studied the expression of the receptors on the cell surface by immunofluorescence, their ability to bind hormone, and their capacity to activate adenylate cyclase. Some mutations allowed us to identify sites that are especially important for receptor function. The substitution Cys390 Trp abolished high affinity hormone binding. Receptor mutated at Asp410 Asn bound the hormone normally, but failed to activate adenylate cyclase. This result underscores the role of this acidic extracellular residue, close to the first transmembrane segment, in signal transmission. The Phe525 Leu substitution also markedly impaired adenylate cyclase activation, underlining the importance of the second intracellular loop in receptor signaling.

Short term treatment with GnRH agonists has been reported to increase plasma gonadotropin alpha-subunit (Gn alpha) levels while decreasing plasma immunoreactive LH (IR-LH) levels. In this study we examined the effect of D-Trp6-LHRH (LHRH-A) in microcapsules (60 micrograms/kg, im, every 28 days for 1 yr) in 13 girls suffering from precocious puberty. Plasma IR-Gn alpha was measured by RIA; plasma IR-LH and IR-FSH were measured by both polyclonal RIAs and monoclonal immunoradiometric assays (IRMA). Before treatment, basal IR-LH and IR-FSH levels and peak responses to LHRH measured by both RIA and IRMA were similar, and the Gn alpha response paralleled that of LH. After the first injection of LHRH-A, RIA LH levels were significantly higher than pretreatment levels until day 21, while IRMA LH levels transiently increased, but returned to pretreatment levels by day 7 and became lower thereafter (P less than 0.005). Plasma IR-Gn alpha levels increased from days 3-21 (P less than 0.05). After 1.5 months of treatment, basal RIA LH levels remained detectable and not different from pretreatment levels; IRMA LH levels were very low. The mean RIA and IRMA LH responses to LHRH were decreased at 1.5 and 12 months (P less than 0.01). Basal plasma RIA and IRMA FSH levels were similar during treatment (P greater than 0.05) and significantly lower than pretreatment values (P less than 0.01). The mean RIA and IRMA FSH responses to LHRH decreased significantly at 1.5 months (P less than 0.001). After 12 months, both RIA and IRMA FSH responses were increased, but IRMA values were significantly lower than RIA values. A sustained increase in basal Gn alpha values occurred, but there was a tendency for the peak levels after LHRH treatment to decrease, becoming significantly lower than pretreatment peak levels after 1 yr. The chromatographic analysis on Sephadex G-100 of a pool of plasma samples collected during a LHRH test in three children treated for 6 months indicated that IR-Gn alpha coeluted with [125I]Gn alpha. The large discrepancy between RIA and IRMA LH values suggests the secretion of unusual LH molecules which are recognized by RIA but not by IRMA. The sustained release of large amounts of IR-Gn alpha indicates dissociated effects of LHRH-A on alpha- and beta-subunit secretion by the gonadotrophs. The sustained response of Gn alpha to LHRH demonstrates that gonadotroph cell LHRH receptors are still responsive to LHRH during treatment with a LHRH agonist.