BackgroundKallmann syndrome (KS), comprised of congenital hypogonadotropic hypogonadism (HH) and anosmia, is a clinically and genetically heterogeneous disorder. Its exact incidence is currently unknown, and a mutation in one of the identified KS genes has only been found in ~30% of the patients.MethodsHerein, we investigated epidemiological, clinical, and genetic features of KS in Finland.ResultsThe minimal incidence estimate of KS in Finland was 1:48 000, with clear difference between males (1:30 000) and females (1:125 000) (p = 0.02). The reproductive phenotype of 30 probands (25 men; 5 women) ranged from severe HH to partial puberty. Comprehensive mutation analysis of all 7 known KS genes (KAL1, FGFR1, FGF8, PROK2, PROKR2, CHD7, and WDR11) in these 30 well-phenotyped probands revealed mutations in KAL1 (3 men) and FGFR1 (all 5 women vs. 4/25 men), but not in other genes.ConclusionsOur results suggest that Finnish KS men harbor mutations in gene(s) yet-to-be discovered with sex-dependent penetrance of the disease phenotype. In addition, some KS patients without CHD7 mutations display CHARGE-syndrome associated phenotypic features (e.g. ear or eye anomalies), possibly implying that, in addition to CHD7, there may be other genes associated with phenotypes ranging from KS to CHARGE.

BackgroundCongenital hypogonadotropic hypogonadism (HH) is a rare cause for delayed or absent puberty. These patients may recover from HH spontaneously in adulthood. To date, it is not possible to predict who will undergo HH reversal later in life. Herein we investigated whether Finnish patients with reversal of congenital hypogonadotropic hypogonadism (HH) have common phenotypic or genotypic features.Methods and FindingsThirty-two male HH patients with anosmia/hyposmia (Kallmann Syndrome, KS; n = 26) or normal sense of smell (nHH; n = 6) were enrolled (age range, 18–61 yrs). The patients were clinically examined, and reversal of HH was assessed after treatment withdrawal. KAL1, FGFR1, FGF8, PROK2, PROKR2, CHD7, WDR11, GNRHR, GNRH1, KISS1R, KISS1, TAC3, TACR3, and LHβ were screened for mutations. Six HH patients (2 KS, 4 nHH) were verified to have reversal of HH. In the majority of cases, reversal occurred early in adulthood (median age, 23 yrs; range, 21–39 yrs). All had spontaneous testicular growth while on testosterone replacement therapy (TRT). One nHH subject was restarted on TRT due to a decline in serum T. Two reversal variants had a same GNRHR mutation (R262Q), which was accompanied by another GNRHR mutation (R139H or del309F). In addition, both of the KS patients had a mutation in CHD7 (p.Q51X) or FGFR1 (c.91+2T>A).ConclusionsConsiderable proportion of patients with HH (8% of KS probands) may recover in early adulthood. Spontaneous testicular enlargement during TRT was highly suggestive for reversal of HH. Those with the GNRHR mutation R262Q accompanied by another GNRHR mutation may be prone to reversal, although even patients with a truncating mutation in CHD7 or a splice-site mutation in FGFR1 can recover. We recommend that all adolescents and young adults with congenital HH should be informed on the possibility of reversal.

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Patients with congenital hypogonadotropic hypogonadism (HH) may have reduced peak bone mass in early adulthood, and increased risk for osteoporosis despite long-term hormonal replacement therapy (HRT). To investigate the relationship between HRT history and measures of bone health in patients with HH, we recruited 33 subjects (24 men, nine women; mean age 39.8 years, range: 24.0-69.1) with congenital HH (Kallmann syndrome or normosmic HH). They underwent clinical examination, were interviewed and medical charts were reviewed. Twenty-six subjects underwent dual-energy X-ray absorptiometry for evaluation of BMD of lumbar spine, hip, femoral neck and whole body; body composition and vertebral morphology were evaluated in 22 and 23 subjects, respectively. Circulating PINP, ICTP and sex hormone levels were measured. HRT history clearly associated to bone health: BMDs of lumbar spine, femoral neck, hip and whole body were lower in subjects (n = 9) who had had long (≥5 years) treatment pauses or low dose testosterone (T) treatment as compared to subjects without such history (n = 17; all p-values < 0.05). In addition, fat mass and body mass index (BMI) were significantly higher in men with deficient treatment history (median fat mass: 37.5 vs. 23.1%, p = 0.005; BMI: 32.6 vs. 25.2 kg/m(2), p < 0.05). Serum PINP correlated with ICTP (r(s) = 0.61; p < 0.005) in men, but these markers correlated neither with circulating T, nor with serum estradiol levels in women. In conclusion, patients with congenital HH require life-long follow-up to avoid inadequate HRT, long treatment pauses and further morbidity.