Whole-exome sequencing uncovers new variants in GDF15 associated with hyperemesis gravidarum

Multi-ancestry GWAS of severe pregnancy nausea and vomiting identifies risk loci associated with appetite, insulin signaling, and brain plasticity

While most pregnancies are affected by nausea and vomiting, hyperemesis gravidarum (HG) is at the severe end of the clinical spectrum and is associated with dehydration, undernutrition, and adverse maternal, fetal, and child outcomes. Herein we performed a multi-ancestry genome-wide association study (GWAS) of severe nausea and vomiting of pregnancy of 10,974 cases and 461,461 controls across European, Asian, African, and Latino ancestries. We identified ten significantly associated loci, of which six were novel (SLITRK1, SYN3, IGSF11, FSHB, TCF7L2, and CDH9), and confirmed previous genome-wide significant associations with risk genes GDF15, IGFBP7, PGR, and GFRAL. In a spatiotemporal analysis of placental development, GDF15 and TCF7L2 were expressed primarily in extra villous trophoblast, and using a weighted linear model of maternal, paternal, and fetal effects, we confirmed opposing effects for GDF15 between maternal and fetal genotype. Conversely, IGFBP7 and PGR were primarily expressed in developing maternal spiral arteries during placentation, with effects limited to the maternal genome. Risk loci were found to be under significant evolutionary selection, with the strongest effects on nausea and vomiting mid-pregnancy. Selected loci were associated with abnormal pregnancy weight gain, pregnancy duration, birth weight, head circumference, and pre-eclampsia. Potential roles for candidate genes in appetite, insulin signaling, and brain plasticity provide new pathways to explore etiological mechanisms and novel therapeutic avenues.

Genetic disorders in maternal medicine

The role of genetic testing within maternal medicine is expanding. Advancing technology and the increasing availability of genetic testing have seen more patients receiving a genetic diagnosis than ever before. Improved healthcare and understanding of these rare diseases means that many patients are living well into their reproductive years and starting families. Individual diseases are considered by their patterns of inheritance i.e. autosomal recessive, autosomal dominant and chromosomal diseases. This chapter specifically addresses the following examples and outlines an approach to pre-conceptual and pregnancy management; autosomal recessive (cystic fibrosis, phenylketonuria), autosomal dominant (osteogenesis imperfecta, vascular Ehlers-Danlos syndrome) and chromosomal (Turner syndrome). For many rare and ultrarare genetic diseases, there may be no clear guidelines or consensus on the correct management in pregnancy. This chapter seeks to provide a framework for the clinician to use to address the unique needs and risk profile of these patients in pregnancy and pre-conceptually and plan accordingly. The role of pharmacogenetics in maternal medicine, the future of education in genetics for patients and clinicians and the important role of genetic counselling are all considered in this chapter. This overview highlights the important role of genetics in maternal medicine and how this can inform management and planning for the safe care of mother and baby.

Multi-ancestry GWAS of severe pregnancy nausea and vomiting identifies risk loci associated with appetite, insulin signaling, and brain plasticity

While most pregnancies are affected by nausea and vomiting, hyperemesis gravidarum (HG) is at the severe end of the clinical spectrum and is associated with dehydration, undernutrition, and adverse maternal, fetal, and child outcomes. Herein we performed a multi-ancestry genome-wide association study (GWAS) of severe nausea and vomiting of pregnancy of 10,974 cases and 461,461 controls across European, Asian, African, and Latino ancestries. We identified ten significantly associated loci, of which six were novel (SLITRK1, SYN3, IGSF11, FSHB, TCF7L2, and CDH9), and confirmed previous genome-wide significant associations with risk genes GDF15, IGFBP7, PGR, and GFRAL. In a spatiotemporal analysis of placental development, GDF15 and TCF7L2 were expressed primarily in extra villous trophoblast, and using a weighted linear model of maternal, paternal, and fetal effects, we confirmed opposing effects for GDF15 between maternal and fetal genotype. Conversely, IGFBP7 and PGR were primarily expressed in developing maternal spiral arteries during placentation, with effects limited to the maternal genome. Risk loci were found to be under significant evolutionary selection, with the strongest effects on nausea and vomiting mid-pregnancy. Selected loci were associated with abnormal pregnancy weight gain, pregnancy duration, birth weight, head circumference, and pre-eclampsia. Potential roles for candidate genes in appetite, insulin signaling, and brain plasticity provide new pathways to explore etiological mechanisms and novel therapeutic avenues.

Risk Factors for Infusions, Emergency Room Visits and Hospitalizations for Hyperemesis Gravidarum: New Data and Literature Review

Purpose

Few factors have been identified that increase the risk of visits (hospital emergency room or inpatient stays) due to hyperemesis gravidarum (HG). The purpose of this study is to understand trends in HG management and identify variables increasing visit frequency so that strategies may be developed to reduce hospital utilization.

Study Design

An online survey was posted on the Hyperemesis Education and Research Foundation website and social media between June 2022 and May 2023. Participants had previous or current severe pregnancy nausea and vomiting. Respondents were asked about themselves and their HG experience, including weight loss, medications, infusion care, and visit frequency. Odds ratios, p-values, and 95% confidence intervals were calculated via MedCalc to analyze the significance of each factor, and Spearman rank correlations were analyzed via SPSS for associations of ondansetron usage with visits and weight loss. Microsoft Excel and SPSS were used to calculate treatment and visit frequencies.

Results

Survey data from 1220 respondents who reported a current or prior pregnancy with HG were included in this study. Respondents were primarily White, from the US, and had at least one visit due to HG. Participants with a visit were significantly more likely to be a person of color (POC), unable to work, have no children, and lose over 15 pounds (6.8 kg). Those who took medications as prescribed had fewer visits. No medication combination or dose was found to be significantly more effective in preventing weight loss or repeat hospital visits.

Conclusion

Risk factors predicting visits included POC, not having children, being too sick to work, and having extreme weight loss. Utilization of medication and nutritional therapies is inconsistent and inadequate in this population, which may increase visit frequency.

Identification and characterization of human GDF15 knockouts

Growth differentiation factor 15 (GDF15) is a secreted protein that regulates food intake, body weight and stress responses in pre-clinical models1. The physiological function of GDF15 in humans remains unclear. Pharmacologically, GDF15 agonism in humans causes nausea without accompanying weight loss2, and GDF15 antagonism is being tested in clinical trials to treat cachexia and anorexia. Human genetics point to a role for GDF15 in hyperemesis gravidarum, but the safety or impact of complete GDF15 loss, particularly during pregnancy, is unknown3-7. Here we show the absence of an overt phenotype in human GDF15 loss-of-function carriers, including stop gains, frameshifts and the fully inactivating missense variant C211G3. These individuals were identified from 75,018 whole-exome/genome-sequenced participants in the Pakistan Genomic Resource8,9 and recall-by-genotype studies with family-based recruitment of variant carrier probands. We describe 8 homozygous ('knockouts') and 227 heterozygous carriers of loss-of-function alleles, including C211G. GDF15 knockouts range in age from 31 to 75 years, are fertile, have multiple children and show no consistent overt phenotypes, including metabolic dysfunction. Our data support the hypothesis that GDF15 is not required for fertility, healthy pregnancy, foetal development or survival into adulthood. These observations support the safety of therapeutics that block GDF15.

GDF15 Targeting for Treatment of Hyperemesis Gravidarum

Nausea and vomiting during pregnancy (NVP), particularly its severe form, Hyperemesis gravidarum (HG), affects up to 70% of pregnancies and significantly impacts the quality of life for those with the condition as well as generates a great economic burden, with annual costs exceeding $1.7 billion in the United States. Despite the available treatments targeting neurotransmitters like serotonin and dopamine, many patients experience inadequate relief and suffer from severe side effects, including headaches and dizziness. Recent research has underscored the role of GDF15, a protein mainly produced by the placenta and linked to NVP symptoms. This protein, part of the TGF-β superfamily, has been implicated in appetite and weight regulation and is altered in those with HG due to specific genetic mutations. Addressing the challenges of delivering effective treatments, current innovations focus on targeting GDF15 to reduce symptoms while ensuring fetal safety. Promising therapeutic strategies include non-IgG immunotherapies, small peptide and molecule antagonists, and novel administration methods such as transdermal patches. These approaches aim to optimize dosage and reduce adverse effects. The effective development and testing of these treatments necessitate advanced animal models that closely resemble human pregnancy physiology, highlighting the need for further research and funding. This ongoing research holds significant potential to improve the clinical outcomes for HG patients and decrease the economic impact on healthcare systems, urging a dedicated response from the scientific and medical communities to advance these promising treatments.

Nausea and vomiting in pregnancy (NVP) in Chinese pregnant women: a cross-sectional study

BACKGROUND

This study addresses the scarcity of research on nausea and vomiting in pregnancy (NVP) in China. It aims to explore the current NVP status in the country using validated questionnaires, analyze associated factors, and provide a useful reference for future research. The study also compares results from different assessment tools.

METHODS

Online questionnaires were utilized to gather data from 535 pregnant women across 24 provinces. Demographic, pregnancy, and NVP-related information were collected. NVP severity was assessed using Pregnancy-Unique Quantification of Emesis and Nausea (PUQE) and the Rhodes Index of Nausea, Vomiting, and Retching (RINVR) scales. Ordinal logistic regression identified factors linked to NVP severity. Differences between PUQE and RINVR assessments were compared.

RESULTS

NVP prevalence exceeded 90%, with 96.1% assessed by PUQE and 90.8% by RINVR. Incidence decreased from nausea to retching and vomiting. Severe NVP correlated with reduced gestational weight gain, younger age, fewer gestational weeks, and living in North (all P values < 0.05). There was moderate consistency between PUQE and RINVR assessments. The NVP prevalence assessed by the PUQE is higher than that assessed by the RINVR in the same population. However, the proportion of NVP levels above moderate assessed by RINVR is greater than that assessed by PUQE.

CONCLUSIONS

NVP is highly prevalent among Chinese pregnant women, with nausea being predominant. RINVR assessments may be better able to identify severe NVP, thereby improving the low treatment rates for severe NVP.

Re-examining the adaptive function of nausea and vomiting in pregnancy

Nausea and vomiting in pregnancy (NVP) have been proposed to have a prophylactic function. In this review, I re-examine NVP from an evolutionary perspective in light of new research on NVP. First, current evidence suggests that the observed characteristics of NVP does not align well with a prophylactic function. Further, NVP is typically associated with high costs for pregnant women, while moderate-to-severe NVP is associated with increased risks of poorer foetal/birth outcomes. In contrast, mild NVP limited to early pregnancy may associate with improved foetal outcomes-indicating a potential evolutionary benefit. Second, researchers have recently identified growth differentiation factor 15 (GDF15) to cause NVP, with implications that low-levels of pre-conception GDF15 (associated with lower cellular stress/inflammation) may increase risks/symptoms of NVP. If so, NVP in contemporary post-industrialized populations may be more severe due to environmental mismatch, and the current symptomology of NVP in such populations should not be viewed as a typical experience of pregnancy.

[Hyperemesis Gravidarum - an Interprofessional and Interdisciplinary Challenge - Evidence-Based Review]

Hyperemesis gravidarum (HG) is a multifactorial disease characterized by severe and persisting nausea and vomiting, impairment of oral intake, weight loss of at least 5%, electrolyte abnormalities, and dehydration. The prevalence of HG ranges from 0.3 to 10% worldwide. The diagnosis is made by the patient's prehistory, clinical symptoms, physical examination, and the typical laboratory abnormalities. Therapeutic cornerstones are nutrition advice, consultation of life style, psychological/psychosocial support of the mother as well as the administration of antiemetics in a stepwise approach, depending on the severity of symptoms, and finally admission to hospital in severe cases. Treatment of patients requires close interprofessional and interdisciplinary cooperation.

Hyperemesis gravidarum theories dispelled by recent research: a paradigm change for better care and outcomes

Nausea and vomiting (NVP) affect most pregnant women. At the severe end of the clinical spectrum, hyperemesis gravidarum (HG) can be life-threatening. The condition is fraught with misconceptions that have slowed progress and left women undertreated. Herein, recent scientific advances are presented that dispel common myths associated with HG related to maternal/offspring outcomes, etiology, and evolution. There is now strong evidence that (i) HG is associated with poor outcomes, (ii) a common cause of NVP and HG has been identified, and (iii) NVP is likely a protective evolutionary mechanism that occurs throughout the animal kingdom but is no longer necessary for human survival. Therefore, it is encouraging that we are finally on the cusp of testing treatments that may put an end to unnecessary suffering.

"Navigating in a maze without a map". Partners' experiences of hyperemesis gravidarum- a qualitative study

OBJECTIVE

A supportive environment for women with Hyperemesis Gravidarum is crucial but not always provided. There is a lack of research regarding Hyperemesis Gravidarum, its impact on the family, and the partner's perception of supporting their spouse. Thus, this study aims to explore partners' experiences of Hyperemesis Gravidarum during their spousés pregnancy.

METHODS

Data were gathered through 13 individual, semi-structured, in-depth, digital interviews with partners of women who had experienced Hyperemesis Gravidarum and analysed with Qualitative Content Analysis. The partners were recruited through advertisement on a social media platform and were exclusively males, representing 8 of 21 Swedish regions. The mean age was 34, and they had, on average, 1 previous child. The mean time from the experience to the interview was 12 months.

FINDINGS

The main theme, "Navigating in a maze without a map", explains partners' situation as stressful and demanding when their spouse suffers from Hyperemesis Gravidarum, with insufficient support and guidance from healthcare providers. The analysis resulted in three themes: "Standing alone with a demanding responsibility", "Being in a lottery when facing healthcare", and "Climbing the mountain together." The themes display challenges within everyday life and healthcare, as well as strained relations within the family.

CONCLUSION

Partners experience a need to support their spouse in every aspect of daily life and advocate for adequate healthcare. Healthcare professionals must support and acknowledge the partners' struggles during the demanding situation with Hyperemesis Gravidarum.

Genome-wide association study of nausea and vomiting during pregnancy in Japan: the TMM BirThree Cohort Study

BACKGROUND

Nausea and vomiting during pregnancy (NVP) and hyperemesis gravidarum (HG), common conditions affecting most pregnant women, are highly heritable and associated with maternal and fetal morbidity. However, the pathologies underlying NVP and HG and their associated loci are scarce.

METHODS

We performed genome-wide association studies (GWAS) of NVP in pregnant women (n = 23,040) who participated in the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study in Japan from July 2013 to March 2017. Participants were divided into discovery (n = 9,464) and replication (n = 10,051) stages based on the platform used for their genotyping. Loci that achieved the genome-wide significance level (p < 5.0 × 10- 8) in the discovery stage were selected for genotyping in the replication stage. A meta-analysis integrating the discovery and replication stage results (n = 19,515) was conducted. NVP-related variables were identified as categorical or continuous.

RESULTS

GWAS analysis in the discovery phase revealed loci linked to NVP in two gene regions, 11q22.1 (rs77775955) and 19p13.11 (rs749451 and rs28568614). Loci in these two gene regions have also been shown to be associated with HG in a White European population, indicating the generalizability of the GWAS analyses conducted in this study. Of these, only rs749451 and rs28568614 at 19p13.11 reached the genome-wide suggestive level (p < 1.0 × 10- 5) in the replication stage; however, both loci were significant in the meta-analysis.

CONCLUSIONS

NVP-related loci were identified in the Japanese population at 11q22.1 and 19p13.11, as reported in previous GWAS. This study contributes new evidence on the generalizability of previous GWAS on the association between genetic background and NVP.

GDF15 linked to maternal risk of nausea and vomiting during pregnancy

GDF15, a hormone acting on the brainstem, has been implicated in the nausea and vomiting of pregnancy, including its most severe form, hyperemesis gravidarum (HG), but a full mechanistic understanding is lacking1-4. Here we report that fetal production of GDF15 and maternal sensitivity to it both contribute substantially to the risk of HG. We confirmed that higher GDF15 levels in maternal blood are associated with vomiting in pregnancy and HG. Using mass spectrometry to detect a naturally labelled GDF15 variant, we demonstrate that the vast majority of GDF15 in the maternal plasma is derived from the feto-placental unit. By studying carriers of rare and common genetic variants, we found that low levels of GDF15 in the non-pregnant state increase the risk of developing HG. Conversely, women with β-thalassaemia, a condition in which GDF15 levels are chronically high5, report very low levels of nausea and vomiting of pregnancy. In mice, the acute food intake response to a bolus of GDF15 is influenced bi-directionally by prior levels of circulating GDF15 in a manner suggesting that this system is susceptible to desensitization. Our findings support a putative causal role for fetally derived GDF15 in the nausea and vomiting of human pregnancy, with maternal sensitivity, at least partly determined by prepregnancy exposure to the hormone, being a major influence on its severity. They also suggest mechanism-based approaches to the treatment and prevention of HG.

The Nutritional Online sUrvey for pRegnancy Induced Sickness & Hyperemesis (NOURISH) study: results from the first trimester

BACKGROUND

Hyperemesis gravidarum (HG) is severe pregnancy sickness, often leading to dehydration, weight loss and electrolyte disturbances. Little is known about nutritional intake and its consequences in those affected. The aim of this study was to explore the first trimester nutritional intake and clinical characteristics in those with severe sickness.

METHOD

Recruitment was via the social media accounts of national pregnancy charities. The eligibility criteria were as follows: between 6 and 11 weeks pregnant, age ≥18 years and residing in the UK. Participants completed a self-report online questionnaire including the Pregnancy Unique Quantification of Emesis 24 (PUQE24) score and a 3-day online diet diary. Groups were compared by PUQE24 categories. Nutritional intakes were compared to dietary reference values.

RESULTS

One hundred sixty-six participants took part in the study: 36 categorised with mild, 109 with moderate and 21 with severe symptoms at a median gestation of 8.1 (interquartile range [IQR] 3) weeks. Those in the severe category had significantly higher weight loss (3.0 kg, IQR 3.5) than the mild category (0.0 kg, IQR 0.9). In those who completed the diet diary (n = 70), intakes of energy, carbohydrate, protein, fat, fibre, calcium, iron, zinc, thiamine, riboflavin, folate and vitamin C were all significantly lower in the severe category (p < 0.05). The severe group consumed only 39.5% and 41.6% of energy and protein needs, respectively, and were more likely to stop taking micronutrient supplements (p < 0.05).

CONCLUSION

Nutritional and supplement intake in those with severe pregnancy sickness was poor; however, intake across all participants was suboptimal. Future research should investigate how to improve nutritional intake across all categories of pregnancy sickness.

Fetally-encoded GDF15 and maternal GDF15 sensitivity are major determinants of nausea and vomiting in human pregnancy

Human pregnancy is frequently accompanied by nausea and vomiting that may become severe and life-threatening, as in hyperemesis gravidarum (HG), the cause of which is unknown. Growth Differentiation Factor-15 (GDF15), a hormone known to act on the hindbrain to cause emesis, is highly expressed in the placenta and its levels in maternal blood rise rapidly in pregnancy. Variants in the maternal GDF15 gene are associated with HG. Here we report that fetal production of GDF15, and maternal sensitivity to it, both contribute substantially to the risk of HG. We found that the great majority of GDF15 in maternal circulation is derived from the feto-placental unit and that higher GDF15 levels in maternal blood are associated with vomiting and are further elevated in patients with HG. Conversely, we found that lower levels of GDF15 in the non-pregnant state predispose women to HG. A rare C211G variant in GDF15 which strongly predisposes mothers to HG, particularly when the fetus is wild-type, was found to markedly impair cellular secretion of GDF15 and associate with low circulating levels of GDF15 in the non-pregnant state. Consistent with this, two common GDF15 haplotypes which predispose to HG were associated with lower circulating levels outside pregnancy. The administration of a long-acting form of GDF15 to wild-type mice markedly reduced subsequent responses to an acute dose, establishing that desensitisation is a feature of this system. GDF15 levels are known to be highly and chronically elevated in patients with beta thalassemia. In women with this disorder, reports of symptoms of nausea or vomiting in pregnancy were strikingly diminished. Our findings support a causal role for fetal derived GDF15 in the nausea and vomiting of human pregnancy, with maternal sensitivity, at least partly determined by pre-pregnancy exposure to GDF15, being a major influence on its severity. They also suggest mechanism-based approaches to the treatment and prevention of HG.

Cancer cachexia as a blueprint for treating obesity

Effective pharmacological treatments to achieve significant and sustained weight loss in obese individuals remain limited. Here, we apply a 'reverse engineering' approach to cancer cachexia, an extreme form of dysregulated energy balance resulting in net catabolism. We discuss three phenotypic features of the disease, summarize the underlying molecular checkpoints, and explore their translation to obesity research. We then provide examples for established pharmaceuticals, which follow a reverse engineering logic, and propose additional targets that may be of relevance for future studies. Finally, we argue that approaching diseases from this perspective may prove useful as a generic strategy to fuel the development of innovative therapies.

Clinical advances: pregnancy in gastroenterologic and hepatic conditions

The fields of gastroenterology and hepatology, along with endoscopic practice, have seen significant changes and innovations to practice in just the past few years. These practice changes are not limited to gastroenterology, but maternal fetal medicine and the care of the pregnant person have become increasingly more sophisticated as well. Gastroenterologists are frequently called on to provide consultative input and/or perform endoscopy during pregnancy. To be able to provide the best possible care to these patients, gastroenterologists need to be aware of (and familiar with) the various nuances and caveats related to the care of pregnant patients who either have underlying gastrointestinal (GI) conditions or present with GI and liver disorders. Here, we offer a clinical update with references more recent than 2018, along with a few words about SARS-CoV-2 infection and its relevance to pregnancy.

Anti-emetic effects of thalidomide: Evidence, mechanism of action, and future directions

The rationale for using thalidomide (THD) as a treatment for nausea and vomiting during pregnancy in the late 1950s appears to have been based on its sedative or hypnotic properties. In contrast to contemporaneous studies on the anti-emetic activity of phenothiazines, we were unable to identify publications reporting preclinical or clinical evaluation of THD as an anti-emetic. Our survey of the literature revealed a clinical study in 1965 showing THD reduced vomiting in cancer chemotherapy which was substantiated by similar studies from 2000, particularly showing efficacy in the delayed phase of chemotherapy-induced nausea and vomiting. To identify the mechanism(s) potentially involved in thalidomide's anti-emetic activity we reviewed its pharmacology in the light of nausea and vomiting mechanisms and their pharmacology with a particular emphasis on chemotherapy and pregnancy. The process identified the following potential mechanisms: reduced secretion of Growth Differentiation Factor 15, suppression of inflammation/prostaglandin production, downregulation of cytotoxic drug induced upregulation of iNOS, and modulation of BK (KCa1.1) channels and GABAA/glutamate transmission at critical points in the emetic pathways (nucleus tractus solitarius, area postrema). We propose ways to investigate these hypothesized mechanisms and discuss the associated challenges (e.g., objective quantification of nausea) in addition to some of the more general aspects of developing novel drugs to treat nausea and vomiting.

The role of serum ADAMTS-1 levels in Hyperemesis Gravidarum

Background

We aimed to investigate the levels of ADAMTS-1, which is secreted from the extracellular matrix during trophoblastic invasion in hyperemesis gravidarum (HEG).

Methods

In this cross-sectional study, we compared 45 HEG patients aged between 21 and 34 in terms of ADAMTS-1 levels with a control group consisting of 44 healthy pregnant women. The demographic characteristics and several laboratory parameters of the patients were recorded. Both groups were also compared in terms of ketonuria. We evaluated the correlation between ADAMTS-1 levels and ketonuria.

Results

The 2 groups were matched in terms of age, gestational age, gravidity, parity, and body mass index. Some inflammatory markers, such as neutrophil count, MPV, PDW, and PCT levels, were significantly higher in the HEG groups compared to the control group (all p < 0.05). However, mean MCV and serum TSH levels were statistically significantly lower in this group (both p < 0.001). ADAMTS-1 levels were 12.6 ± 1.4 ng/ml in the HEG group and 6.2 ± 1.6 ng/ml in the control group (p < 0.001). It was significantly and positively correlated with urine ketone, neutrophil count, and PDW, whereas negatively correlated with MCV and TSH value in the HEG group. ROC analysis showed that a threshold value of 11.275 ng/ml for ADAMTS-1 predicted HEG patients with a sensitivity of 60% and specificity of 95.5%.

Conclusion

ADAMTS-1 serum levels are increased in HEG patients, and there is a positive correlation between ADAMTS-1 levels and ketonuria.