Prenatal, newborn and childhood factors and the timing of puberty in boys and girls.

BACKGROUND: Our aim was to determine if prenatal factors, gestational age, birth weight and length, and childhood body mass index (BMI) are associated with the timing of puberty. METHODS: Our population-based study comprised 4826 girls and 5112 boys born between 1997 and 2002. Multiple linear regression modeled the relationships between the maternal and child predictors and the age at peak height velocity (PHV). RESULTS: Maternal smoking throughout pregnancy was associated with earlier age at PHV (-1.8 months in girls, 95%CI = -3.2 to -0.3, p = 0.015 and -1.7 months in boys, 95%CI = -3.1 to -0.3, p = 0.016). Older gestational age predicted later age at PHV in boys. One SDS increase in birth weight led to 1.7 months later age at PHV in girls (95%CI = 1.2 to 2.2, p < 0.001) and 0.8 months in boys (95%CI = 0.2 to 1.3, p = 0.005). At the age of 9 years, each increment of BMI by 1 kg/m2 was associated with 1.7 months (95%CI = -1.9 to -1.6, p < 0.001) and 1.3 months (95%CI = -1.4 to -1.1, p < 0.001) earlier age at PHV in girls and boys, respectively. CONCLUSIONS: Fetal exposure to smoking can potentially exert enduring effects on pubertal timing. Birth weight and childhood nutritional status are significant determinants of pubertal timing in both sexes. IMPACT: Maternal smoking was associated with earlier timing of puberty and greater birth weight with later timing of puberty in both girls and boys. Most previous studies have focused on girls and used surveys to assess pubertal development, but we studied both sexes and used the same objective measure (age at peak height velocity) for the timing of puberty. Our study increases knowledge especially regarding factors associated with the timing of puberty among boys.

Polygenic embryo screening: quo vadis?

Recently, the use of polygenic risk scores in embryo screening (PGT-P) has been introduced on the premise of reducing polygenic disease risk through embryo selection. However, it has been met with extensive critique: considered "technology-driven" rather than "evidence-based", concerns exist about its validity, utility, ethics, and societal effects. Its scientific foundations and criticisms thus need to be carefully considered. However, seeing as PGT-P is already offered in some settings, further questions need to be addressed, in order to give due diligence to various aspects of PGT-P. By examining the complexities of clinical introduction of PGT-P, we discuss whether PGT-P could be responsibly implemented in the first place, what elements need to be addressed if PGT-P is clinically implemented, and subsequently how counselling and decision-making of its users could be envisaged. By dissecting these elements, we provide an overview of important practical questions of PGT-P and emphasize elements of PGT-P that we think have yet to be given sufficient attention. These questions and elements are for example related to the potential target group, scope, and decision-making possibilities of PGT-P. The aspects we raise are crucial to consider by the scientific community and policy makers for the development of guidelines and/or an ethical framework for PGT-P.

Neuron-Derived Neurotrophic Factor Is Mutated in Congenital Hypogonadotropic Hypogonadism.

Congenital hypogonadotropic hypogonadism (CHH) is a rare genetic disorder characterized by infertility and the absence of puberty. Defects in GnRH neuron migration or altered GnRH secretion and/or action lead to a severe gonadotropin-releasing hormone (GnRH) deficiency. Given the close developmental association of GnRH neurons with the olfactory primary axons, CHH is often associated with anosmia or hyposmia, in which case it is defined as Kallmann syndrome (KS). The genetics of CHH are heterogeneous, and >40 genes are involved either alone or in combination. Several CHH-related genes controlling GnRH ontogeny encode proteins containing fibronectin-3 (FN3) domains, which are important for brain and neural development. Therefore, we hypothesized that defects in other FN3-superfamily genes would underlie CHH. Next-generation sequencing was performed for 240 CHH unrelated probands and filtered for rare, protein-truncating variants (PTVs) in FN3-superfamily genes. Compared to gnomAD controls the CHH cohort was statistically enriched for PTVs in neuron-derived neurotrophic factor (NDNF) (p = 1.40 × 10-6). Three heterozygous PTVs (p.Lys62∗, p.Tyr128Thrfs∗55, and p.Trp469∗, all absent from the gnomAD database) and an additional heterozygous missense mutation (p.Thr201Ser) were found in four KS probands. Notably, NDNF is expressed along the GnRH neuron migratory route in both mouse embryos and human fetuses and enhances GnRH neuron migration. Further, knock down of the zebrafish ortholog of NDNF resulted in altered GnRH migration. Finally, mice lacking Ndnf showed delayed GnRH neuron migration and altered olfactory axonal projections to the olfactory bulb; both results are consistent with a role of NDNF in GnRH neuron development. Altogether, our results highlight NDNF as a gene involved in the GnRH neuron migration implicated in KS.

Deciphering the Transcriptional Landscape of Human Pluripotent Stem Cell-Derived GnRH Neurons: The Role of Wnt Signaling in Patterning the Neural Fate.

Hypothalamic gonadotropin-releasing hormone (GnRH) neurons lay the foundation for human development and reproduction; however, the critical cell populations and the entangled mechanisms underlying the development of human GnRH neurons remain poorly understood. Here, by using our established human pluripotent stem cell-derived GnRH neuron model, we decoded the cellular heterogeneity and differentiation trajectories at the single-cell level. We found that a glutamatergic neuron population, which generated together with GnRH neurons, showed similar transcriptomic properties with olfactory sensory neuron and provided the migratory path for GnRH neurons. Through trajectory analysis, we identified a specific gene module activated along the GnRH neuron differentiation lineage, and we examined one of the transcription factors, DLX5, expression in human fetal GnRH neurons. Furthermore, we found that Wnt inhibition could increase DLX5 expression and improve the GnRH neuron differentiation efficiency through promoting neurogenesis and switching the differentiation fates of neural progenitors into glutamatergic neurons/GnRH neurons. Our research comprehensively reveals the dynamic cell population transition and gene regulatory network during GnRH neuron differentiation.

A review of normative documents on preimplantation genetic testing: Recommendations for PGT-P.

PURPOSE: Recently, preimplantation genetic testing (PGT) for polygenic conditions (PGT-P) has been introduced commercially. In view of the lack of specific guidance on this development, we analyzed normative documents on PGT for monogenic conditions (PGT-M) to understand what we can learn from these documents for recommendations for PGT-P. METHODS: We conducted a systematic review of normative guidelines and recommendations on PGT-M. The aim was to understand what the current consensus and disagreements are on ethical acceptability of PGT-M and how this compares with PGT-P. RESULTS: We analyzed 38 documents by advisory committees at the national, European, and global level. In total, 2 themes were identified, which included the following: (1) what PGT is considered appropriate for and (2) who can make decisions regarding the use of PGT. Many aspects of PGT-M documents apply to PGT-P as well. Additional factors such as the fact that PGT-P screens for risk indications of multiple polygenic conditions increase ethical difficulties regarding severity, risk, autonomy, and informed decision-making. CONCLUSION: On the basis of PGT-M normative documents, we conclude that ethical acceptability for PGT-P is limited. Our findings present various factors that have to be considered for the development of guidelines and the appropriateness of PGT.

Onset and progression of puberty in Klinefelter syndrome.

OBJECTIVE: Klinefelter syndrome (KS) (47,XXY and variants, KS) is the most common sex chromosome disorder in humans. However, little is known about the onset and progression of puberty in patients with KS. In this study, we describe the onset and progression of puberty in a large series of boys with KS in a single tertiary centre. DESIGN AND PATIENTS: Retrospective data (Tanner stages, testicular length, testosterone supplementation, levels of luteinizing hormone [LH] and testosterone) before possible testosterone treatment on 72 KS patients with 47,XXY karyotype were reviewed, and G (n = 59 patients) and P (n = 56 patients) stages were plotted on puberty nomograms. MEASUREMENTS AND RESULTS: One boy had a delayed onset of puberty, as he was at the G1 stage at the age of 13.8 years (-2.2 SDs). No observations of delay were made of boys at Stage G2. The progression of G stages was within normal limits in the majority of patients; only few boys were late at G3 (4.1%; 1 out of 24) and G4 (7.4%; 2 out of 27). Testosterone supplementation was started at the average age of 15.5 years to 35 boys (47%), 2 of whom were over 18 years old. LH level was on average 18.2 IU/L (SD: 6.3 IU/L) and testosterone 9.1 nmol/L (SD: 3.1 nmol/L) when testosterone supplementation was started. CONCLUSIONS: Our results suggest that puberty starts within the normal age limits in boys with KS, and testosterone supplementation is not needed for the initial pubertal progression in the majority of patients.

Serum testosterone and oestradiol predict the growth response during puberty promoting treatment.

OBJECTIVE: The influence of androgens and oestrogens on growth is complex, and understanding their relative roles is important for optimising the treatment of children with various disorders of growth and puberty. DESIGN: We examined the proportional roles of androgens and oestrogens in the regulation of pubertal growth in boys with constitutional delay of growth and puberty (CDGP). The study compared 6-month low-dose intramuscular testosterone treatment (1 mg/kg/month; n = 14) with per oral letrozole treatment (2.5 mg/day; n = 14) which inhibits conversion of androgens to oestrogen. PATIENTS: Boys with CDGP were recruited to a randomized, controlled, open-label trial between 2013 and 2017 (NCT01797718). MEASUREMENTS: The patients were evaluated at 0-, 3- and 6-month visits, and morning blood samples were drawn. Linear regression models were used for data analyses. RESULTS: In the testosterone group (T-group), serum testosterone concentration correlated with serum oestradiol concentration at the beginning of the study and at 3 months, whereas in the letrozole group (Lz-group) these sex steroids correlated only at baseline. Association between serum testosterone level and growth velocity differed between the T and Lz groups, as each nmol/L increase in serum testosterone increased growth velocity 2.7 times more in the former group. Serum testosterone was the best predictor of growth velocity in both treatment groups. In the Lz-group, adding serum oestradiol to the model significantly improved the growth estimate. Only the boys with serum oestradiol above 10 pmol/L had a growth velocity above 8 cm/year. CONCLUSIONS: During puberty promoting treatment with testosterone or aromatase inhibitor letrozole, growth response is tightly correlated with serum testosterone level. A threshold level of oestrogen appears to be needed for an optimal growth rate that corresponds to normal male peak height velocity of puberty. Serum testosterone 1 week after the injection and serum testosterone and oestradiol 3 months after the onset of aromatase inhibitor treatment can be used as biomarkers for treatment response in terms of growth.

Bone structure assessed with pQCT in prepubertal males with delayed puberty or congenital hypogonadotropic hypogonadism.

OBJECTIVE: Congenital hypogonadotropic hypogonadism (CHH) is associated with impaired bone mineral density in adulthood, whereas the estimates on bone structure in adolescents with CHH has not been previously evaluated. This study describes bone structure in CHH patients and compares it to that in boys with constitutional delay of growth and puberty (CDGP). DESIGN: A cross-sectional study. METHODS: Peripheral quantitative computed tomography (pQCT) of non-dominant arm and left leg were performed. Volumetric bone mineral density (BMD), bone mineral content, and area in trabecular and cortical bone compartments were evaluated, and bone age-adjusted Z-scores for the bone parameters were determined. RESULTS: The participants with CHH had more advanced bone age and were older, taller and heavier than the CDGP boys, yet they had lower trabecular BMD in distal radius (147.7 mg/mm3 [95% CI, 128-168 mg/mm3 ] vs. 181.2 mg/mm3 [172-192 mg/mm3 ], p = .002) and distal tibia (167.6 mg/mm3 [145-190 mg/mm3 ] vs. 207.2 mg/mm3 [187-227 mg/mm3 ], p = .012), respectively. CHH males had lower cortical thickness at diaphyseal tibia than the participants with CDGP (p = .001). These between-group differences remained significant in corresponding Z-scores adjusted for bone age and height (p = .001). In CDGP group, serum testosterone correlated positively with trabecular BMD (r = 0.51, p = .013) at distal radius, and estradiol levels correlated positively with trabecular BMD at the distal site of tibia (r = 0.58, p = .004). CONCLUSIONS: Five treatment-naïve male patients with CHH exhibited poorer trabecular BMD than untreated males with CDGP. We speculate that timely low-dose sex steroid replacement in CHH males may benefit skeletal health in adulthood.

Familial central precocious puberty: two novel MKRN3 mutations.

BACKGROUND: Paternally inherited loss-of-function mutations in MKRN3 underlie central precocious puberty (CPP). We describe clinical and genetic features of CPP patients with paternally inherited MKRN3 mutations in two independent families. METHODS: The single coding exon of MKRN3 was analyzed in three patients with CPP and their family members, followed by segregation analyses. Additionally, we report the patients' responses to GnRH analog treatment. RESULTS: A paternally inherited novel heterozygous c.939C>G, p.(Ile313Met) missense mutation affecting the RING finger domain of MKRN3 was found in a Finnish girl with CPP (age at presentation 6 years). Two Polish siblings (a girl presenting with B2 at the age of 4 years and a boy with adult size testes at the age of 9 years) had inherited a novel heterozygous MKRN3 mutation c.1237_1252delGGAGACACATGCTTTT p.(Gly413Thrfs*63) from their father. The girls were treated with GnRH analogs, which exhibited suppression of the hypothalamic-pituitary-gonadal axis. In contrast, the male patient was not treated, yet he reached his target height. CONCLUSIONS: We describe two novel MKRN3 mutations in three CPP patients. The first long-term data on a boy with CPP due to an MKRN3 mutation questions the role of GnRH analog treatment in augmenting adult height in males with this condition. IMPACT: We describe the genetic cause for central precocious puberty (CPP) in two families. This report adds two novel MKRN3 mutations to the existing literature. One of the mutations, p.(Ile313Met) affects the RING finger domain of MKRN3, which has been shown to be important for repressing the promoter activity of KISS1 and TAC3. We describe the first long-term observation of a male patient with CPP due to a paternally inherited MKRN3 loss-of-function mutation. Without GnRH analog treatment, he achieved an adult height that was in accordance with his mid-parental target height.

WDR11-mediated Hedgehog signalling defects underlie a new ciliopathy related to Kallmann syndrome.

WDR11 has been implicated in congenital hypogonadotropic hypogonadism (CHH) and Kallmann syndrome (KS), human developmental genetic disorders defined by delayed puberty and infertility. However, WDR11's role in development is poorly understood. Here, we report that WDR11 modulates the Hedgehog (Hh) signalling pathway and is essential for ciliogenesis. Disruption of WDR11 expression in mouse and zebrafish results in phenotypic characteristics associated with defective Hh signalling, accompanied by dysgenesis of ciliated tissues. Wdr11-null mice also exhibit early-onset obesity. We find that WDR11 shuttles from the cilium to the nucleus in response to Hh signalling. WDR11 regulates the proteolytic processing of GLI3 and cooperates with the transcription factor EMX1 in the induction of downstream Hh pathway gene expression and gonadotrophin-releasing hormone production. The CHH/KS-associated human mutations result in loss of function of WDR11. Treatment with the Hh agonist purmorphamine partially rescues the WDR11 haploinsufficiency phenotypes. Our study reveals a novel class of ciliopathy caused by WDR11 mutations and suggests that CHH/KS may be a part of the human ciliopathy spectrum.

Treatment of gonadotropin deficiency during the first year of life: long-term observation and outcome in five boys.

STUDY QUESTION: What is the peripubertal outcome of recombinant human FSH (r-hFSH) treatment during minipuberty in boys with congenital hypogonadotropic hypogonadism (CHH)? SUMMARY ANSWER: Sertoli-cell response to r-hFSH, given during the minipuberty of infancy, appears insufficient to maintain Sertoli cell function throughout childhood, as evaluated by inhibin B measurements. WHAT IS KNOWN ALREADY: Severe CHH in boys can be diagnosed during the minipuberty of infancy. Combined gonadotropin treatment at that age is suggested to improve testicular endocrine function and future fertility, yet long-term evidence is lacking. STUDY DESIGN, SIZE, DURATION: In this retrospective cohort study, we describe five CHH boys treated with r-hFSH in Helsinki University Hospital or Kuopio University Hospital between 2004 and 2018. Immediate follow-up data (0.1-1.4 months after cessation of the gonadotropin therapy) was available for four boys and long-term observations (at the age of 10.0-12.8 years) was available for three boys. As a retrospective control cohort, we provide inhibin B values of eight untreated CHH boys at the age of 12.7-17.8 years. PARTICIPANTS/MATERIALS, SETTING, METHODS: Four patients had combined pituitary hormone deficiency, and one had CHARGE syndrome due to a CHD7 mutation. The patients were treated at the age of 0.7-4.2 months with r-hFSH (3.4 IU/kg-7.5 IU/kg per week in 2 or 3 s.c. doses for 3-4.5 months) combined with T (25 mg i.m. monthly for three months for the treatment of micropenis). Inhibin B was chosen as the primary outcome measure. MAIN RESULTS AND THE ROLE OF CHANCE: During the r-hFSH + T treatment, inhibin B increased from 76 ± 18 ng/l to 176 ± 80 ng/l (P = 0.04) and penile length increased by 81 ± 50% (P = 0.04). Unexpectedly, two boys with robust inhibin B responses in infancy demonstrated low inhibin B values in peripuberty: declining from 290 ng/l (4 months) to 16 ng/l (12.4 years), and from 207 ng/l (6 months) to 21 ng/l (12.8 years). All boys underwent orchiopexy at 2.0 ± 0.7 years of age. Inhibin B values in long-term follow-up, available for the three boys, did not significantly differ from the untreated CHH controls. LIMITATIONS, REASONS FOR CAUTION: Limitations of this retrospective study are the small number and heterogeneity of the patients and their treatment schemes. WIDER IMPLICATIONS OF THE FINDINGS: We describe the first long-term follow-up data on CHH boys treated with r-hFSH and T as infants. The results from this small patient series suggest that the effects of infant r-hFSH treatment may be transient, and further longitudinal studies are required to determine the efficacy of this treatment approach to optimise the fertility potential in this patient population. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the Finnish foundation for Pediatric Research, the Academy of Finland and the Emil Aaltonen Foundation. The authors have no competing interests. TRIAL REGISTRATION NUMBER: Non-applicable.

Congenital hypogonadotropic hypogonadism, functional hypogonadotropism or constitutional delay of growth and puberty? An analysis of a large patient series from a single tertiary center.

STUDY QUESTION: What diagnoses underlie delayed puberty (DP) and predict its outcome? SUMMARY ANSWER: A multitude of different diagnoses underlie DP, and in boys a history of cryptorchidism, small testicular size and slow growth velocity (GV) predict its clinical course. WHAT IS KNOWN ALREADY: DP is caused by a variety of underlying etiologies. Hormonal markers can be used in the differential diagnosis of DP but none of them have shown complete diagnostic accuracy. STUDY DESIGN, SIZE, DURATION: Medical records of 589 patients evaluated for DP in a single tertiary care center between 2004 and 2014 were retrospectively reviewed. PARTICIPANTS/MATERIALS, SETTING, METHODS: Clinical and biochemical data of 174 boys and 70 girls who fulfilled the criteria of DP were included in the analyses. We characterized the frequencies of underlying conditions and evaluated the predictive efficacy of selected clinical and hormonal markers. MAIN RESULTS AND THE ROLE OF CHANCE: Thirty etiologies that underlie DP were identified. No markers of clinical value could be identified in the girls, whereas a history of cryptorchidism in the boys was associated with an increase in the risk of permanent hypogonadism (odds ratio 17.2 (95% CI; 3.4-85.4, P < 0.001)). The conditions that cause functional hypogonadotropic hypogonadism were more frequent in boys with a GV below 3 cm/yr than in those growing faster (19% vs 4%, P < 0.05). In this series, the most effective markers to discriminate the prepubertal boys with constitutional delay of growth and puberty (CDGP) from those with congenital hypogonadotropic hypogonadism (CHH) were testicular volume (cut-off 1.1 ml with a sensitivity of 100% and a specificity of 91%), GnRH-induced maximal LH (cut-off 4.3 IU/L; 100%, 75%) and basal inhibin B (INHB) level (cut-off 61 ng/L; 90%, 83%). LIMITATIONS, REASONS FOR CAUTION: The main limitation of the study is the retrospective design. WIDER IMPLICATIONS OF THE FINDINGS: Prior cryptorchidism and slow GV are two important clinical cues that may help clinicians to predict the clinical course of DP in boys, whereas markers of similar value could not be identified in girls. In prepubertal boys, testicular size appeared as effective as INHB and GnRH-induced LH levels in the differential diagnosis between CHH and CDGP. STUDY FUNDING/COMPETING INTERESTS: This study was supported by the Academy of Finland (268356), Foundation for Pediatric Research (7495), Sigrid Juselius Foundation (2613) and the Finnish Medical Foundation (011115). The authors have no competing interests to report. TRIAL REGISTRATION NUMBER: Not applicable.

Mutations in FGF17, IL17RD, DUSP6, SPRY4, and FLRT3 are identified in individuals with congenital hypogonadotropic hypogonadism.

Congenital hypogonadotropic hypogonadism (CHH) and its anosmia-associated form (Kallmann syndrome [KS]) are genetically heterogeneous. Among the >15 genes implicated in these conditions, mutations in FGF8 and FGFR1 account for ~12% of cases; notably, KAL1 and HS6ST1 are also involved in FGFR1 signaling and can be mutated in CHH. We therefore hypothesized that mutations in genes encoding a broader range of modulators of the FGFR1 pathway might contribute to the genetics of CHH as causal or modifier mutations. Thus, we aimed to (1) investigate whether CHH individuals harbor mutations in members of the so-called "FGF8 synexpression" group and (2) validate the ability of a bioinformatics algorithm on the basis of protein-protein interactome data (interactome-based affiliation scoring [IBAS]) to identify high-quality candidate genes. On the basis of sequence homology, expression, and structural and functional data, seven genes were selected and sequenced in 386 unrelated CHH individuals and 155 controls. Except for FGF18 and SPRY2, all other genes were found to be mutated in CHH individuals: FGF17 (n = 3 individuals), IL17RD (n = 8), DUSP6 (n = 5), SPRY4 (n = 14), and FLRT3 (n = 3). Independently, IBAS predicted FGF17 and IL17RD as the two top candidates in the entire proteome on the basis of a statistical test of their protein-protein interaction patterns to proteins known to be altered in CHH. Most of the FGF17 and IL17RD mutations altered protein function in vitro. IL17RD mutations were found only in KS individuals and were strongly linked to hearing loss (6/8 individuals). Mutations in genes encoding components of the FGF pathway are associated with complex modes of CHH inheritance and act primarily as contributors to an oligogenic genetic architecture underlying CHH.

Notch signaling regulates the differentiation of neural crest from human pluripotent stem cells.

Neural crest cells are specified at the border between the neural plate and the epiderm. They are capable of differentiating into various somatic cell types, including craniofacial and peripheral nerve tissues. Notch signaling plays important roles during neurogenesis; however, its function during human neural crest development is poorly understood. Here, we generated self-renewing premigratory neural-crest-like cells (pNCCs) from human pluripotent stem cells (hPSCs) and investigated the roles of Notch signaling during neural crest differentiation. pNCCs expressed various neural-crest-specifier genes, including SLUG (also known as SNAI2), SOX10 and TWIST1, and were able to differentiate into most neural crest derivatives. Blocking Notch signaling during the pNCC differentiation suppressed the expression of neural-crest-specifier genes. By contrast, ectopic expression of activated Notch1 intracellular domain (NICD1) augmented the expression of neural-crest-specifier genes, and NICD1 was found to bind to their promoter regions. Notch activity was also required for the maintenance of the premigratory neural crest state, and the suppression of Notch signaling led to the generation of neural-crest-derived neurons. Taken together, we provide a protocol for the generation of pNCCs and show that Notch signaling regulates the formation, migration and differentiation of neural crest from hPSCs.

Childhood growth in boys with congenital hypogonadotropic hypogonadism.

BACKGROUND: We describe childhood growth patterns in a series of well-characterized patients with congenital hypogonadotropic hypogonadism (CHH) with special emphasis on genotype-phenotype correlation. METHODS: We retrospectively evaluated the growth charts of 36 males with CHH (27 from Finland and 9 from Denmark). Fifteen patients (42%) had representative growth measurements during the first year of life. Genetically verified diagnosis of CHH was made in 15 (42%) patients (KAL1, FGFR1, GNRHR, or PROK2). RESULTS: We found a deceleration of growth rate during early childhood. The mean (SD) length standard deviation score (SDS) at birth (0.2 (1.6) SDS) decreased significantly during the first 3 (to -0.9 (1.2) SDS) and 6 mo of life (to -0.7 (1.3) SDS). At the average age of 3 y, mean height SDS (-0.2 (1.3) SDS) did not differ from mid-parental target height (MPH). Mean height SDS reached its nadir (-1.7 (1.4) SDS) at an average age of 15.8 (0.8) years reflecting pubertal failure. Final heights did not differ from MPH. No clear genotype-growth associations emerged. CONCLUSION: Moderate postnatal length deflection is a novel feature of CHH and may reflect early androgen deficiency. Childhood growth patterns are not of clinical value in targeting molecular genetic diagnosis of CHH.

Congenital hypogonadotropic hypogonadism with split hand/foot malformation: a clinical entity with a high frequency of FGFR1 mutations.

PURPOSE: Congenital hypogonadotropic hypogonadism (CHH) and split hand/foot malformation (SHFM) are two rare genetic conditions. Here we report a clinical entity comprising the two. METHODS: We identified patients with CHH and SHFM through international collaboration. Probands and available family members underwent phenotyping and screening for FGFR1 mutations. The impact of identified mutations was assessed by sequence- and structure-based predictions and/or functional assays. RESULTS: We identified eight probands with CHH with (n = 3; Kallmann syndrome) or without anosmia (n = 5) and SHFM, seven of whom (88%) harbor FGFR1 mutations. Of these seven, one individual is homozygous for p.V429E and six individuals are heterozygous for p.G348R, p.G485R, p.Q594*, p.E670A, p.V688L, or p.L712P. All mutations were predicted by in silico analysis to cause loss of function. Probands with FGFR1 mutations have severe gonadotropin-releasing hormone deficiency (absent puberty and/or cryptorchidism and/or micropenis). SHFM in both hands and feet was observed only in the patient with the homozygous p.V429E mutation; V429 maps to the fibroblast growth factor receptor substrate 2α binding domain of FGFR1, and functional studies of the p.V429E mutation demonstrated that it decreased recruitment and phosphorylation of fibroblast growth factor receptor substrate 2α to FGFR1, thereby resulting in reduced mitogen-activated protein kinase signaling. CONCLUSION: FGFR1 should be prioritized for genetic testing in patients with CHH and SHFM because the likelihood of a mutation increases from 10% in the general CHH population to 88% in these patients.

Childhood growth of females with Kallmann syndrome and FGFR1 mutations.

OBJECTIVE: In search of phenotypic cues that would allow early detection of Kallmann syndrome (KS), we evaluated the paediatric phenotypes in a series of females with KS. DESIGN, PATIENTS AND MEASUREMENTS: In this retrospective cohort study, we investigated childhood growth in six females with KS due to mutations in FGFR1 and evaluated their reproductive phenotypes later in life. RESULTS: While growth during early infancy and childhood was within normal limits, a decreasing trend in height SDS already from mid-childhood occurred in most patients. The lowest height SDS (mean, -1·2 SDS) occurred between 14 and 15 years of age, before the start of hormone replacement therapy. As adults, these women required assisted reproductive techniques for fertility. One of the probands passed on her G48S mutation to her son, who showed normal reproductive hormone levels during the minipuberty of infancy. CONCLUSIONS: Early diagnosis of female KS remains a challenge as early phenotypic signs, apart from anosmia, are scarce. Females with KS exhibit a slight reduction in growth rate during mid-childhood, but normal growth rate during the minipuberty of infancy, despite congenital lack of ovarian oestrogen. Women harbouring FGFR1 mutations will have 50% chance of passing on the gene defect to their offspring. We recommend genetic counselling to all females with KS to be carried out as a part of family planning.

A missense mutation in MKRN3 in a Danish girl with central precocious puberty and her brother with early puberty.

BACKGROUND: Idiopathic central precocious puberty (ICPP) results from the premature reactivation of the hypothalamic-pituitary-gonadal axis leading to development of secondary sexual characteristics prior to 8 y in girls or 9 y in boys. Since the initial discovery of mutations in the maternally imprinted MKRN3 gene in 2013, several case reports have described mutations in this gene in ICPP patients from different populations, highlighting the importance of MKRN3 as a regulator of pubertal onset. METHODS: We screened 29 Danish girls with ICPP for mutations in MKRN3. Expression of MKRN3 in human hypothalamic complementary DNA (cDNA) was investigated by PCR. RESULTS: One paternally inherited rare variant, c.1034G>A (p.Arg345His), was identified in one girl with ICPP and in her brother with early puberty. The variant is predicted to be deleterious by three different in silico prediction programs. Expression of MKRN3 was confirmed in adult human hypothalamus. CONCLUSION: Our results are in line with previous studies in which paternally inherited MKRN3 mutations have been found both in males and in females with ICPP or early puberty. Our report further expands the set of MKRN3 mutations identified in ICPP patients across diverse populations, thus supporting the major regulatory function of MKRN3 in pubertal onset.

Neural crest cells: from developmental biology to clinical interventions.

Neural crest cells are multipotent cells, which are specified in embryonic ectoderm in the border of neural plate and epiderm during early development by interconnection of extrinsic stimuli and intrinsic factors. Neural crest cells are capable of differentiating into various somatic cell types, including melanocytes, craniofacial cartilage and bone, smooth muscle, and peripheral nervous cells, which supports their promise for cell therapy. In this work, we provide a comprehensive review of wide aspects of neural crest cells from their developmental biology to applicability in medical research. We provide a simplified model of neural crest cell development and highlight the key external stimuli and intrinsic regulators that determine the neural crest cell fate. Defects of neural crest cell development leading to several human disorders are also mentioned, with the emphasis of using human induced pluripotent stem cells to model neurocristopathic syndromes.

Serum FGF21 increases with hepatic fat accumulation in pediatric onset intestinal failure.

BACKGROUND & AIMS: Previously, FGF21 has been related to glucose and lipid metabolism and liver steatosis. Our aim was to evaluate serum FGF21 levels in pediatric onset intestinal failure (IF). METHODS: Serum FGF21 was measured in 35 IF patients at median age of 7.8 years (range 0.2-27) and 59 matched healthy controls. Thirty patients underwent liver biopsy. RESULTS: Serum FGF21 levels were increased in patients compared to controls [229 pg/ml (21-20,345) vs. 133 pg/ml (7-1607), p=0.018]. Frequency of liver steatosis (60% vs. 50%, p=0.709) was similar during (6/10) and after (10/20) weaning off parenteral nutrition (PN). Patients with steatosis had markedly higher serum FGF21 concentration [626 pg/ml (21-20,345) vs. 108 pg/ml (32-568), p=0.002] and more advanced liver fibrosis [Metavir stage 1.6 (0-4) vs. 0.7 (0-3), p=0.020] without associated inflammation or Mallory body formation. Serum FGF21 levels reflected the degree of steatosis [FGF21 in grade 3 vs. grades 0-2, p<0.001; grade 1 vs. controls, p=0.002], and correlated with steatosis grade (r=0.589, p=0.001). Hepatic steatosis and serum FGF21 showed similar associations with duration of PN and remaining small bowel length (p<0.05 for all). In a multivariate regression model, liver steatosis grade (ß=0.630, p=0.001) predicted serum FGF21 concentration. CONCLUSIONS: In pediatric IF increased serum FGF21 levels reflect liver steatosis, while both are exclusively associated with duration of PN and extent of small intestinal resection. Liver steatosis is coupled with progression of fibrosis without accompanying inflammation. Serum FGF21 assay may be useful for diagnosing liver steatosis in IF patients.