Maternal heterozygosity for a mitochondrial trifunctional protein mutation as a cause for liver disease in pregnancy

Molecular testing in newborn screening: VUS burden among true positives and secondary reproductive limitations via expanded carrier screening panels

PURPOSE

Expanded carrier screening (ECS) gene panels have several limitations, including variable content, current knowledge of disease-causing variants, and differing reporting policies. This study evaluated if the disease-associated variants identified in affected neonates who screened positive by California newborn screening (NBS) for an inherited metabolic disorder (IMD) by tandem mass spectrometry (MS/MS) would likely be reported by ECS gene panels.

METHODS

Retrospective review of neonates referred by the California Department of Public Health for a positive NBS by multianalyte MS/MS from January 1, 2020 through June 30, 2021.

RESULTS

One hundred thirty-six neonates screened positive for ≥1 NBS MS/MS indication. Nineteen neonates (14%) were ultimately diagnosed with an IMD, all of whom had abnormal biochemical testing. Eighteen of the 19 underwent molecular testing; 10 (56%) neonates had ≥1 variants of uncertain significance, 9 of whom were of non-White ancestry. ECS panels would have been negative for 56% (20/36) of parents with an affected neonate, 85% (17/20) of whom were of non-White ancestry.

CONCLUSION

The number of variants of uncertain significance identified in this cohort highlights the need for more diversified variant databases. Due in part to the lack of diversity in currently sequenced populations, genomic sequencing cannot replace biochemical testing for the diagnosis of an IMD.

A novel HADHA variant associated with an atypical moderate and late-onset LCHAD deficiency

Background

Long chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is a rare inherited disease caused by pathogenic variants of HADHA gene. Along with signs common to fatty acid oxidation defects (FAOD), specific retina and heart alterations are observed. Because long-chain fatty acid oxidation is selectively affected, supplementations with short/medium-chain fats represent energetic sources bypassing the enzymatic blockade. Here, we report on an atypical presentation of the disease.

Methods

Clinical features were described with medical explorations including ophthalmic and cardiac examination. Biological underlying defects were investigated by measurements of biochemical metabolites and by fluxomic studies of mitochondrial β-oxidation. Whole exome sequencing and molecular validation of variants confirmed the diagnosis.

Results

The patient has developed at nine years an unlabeled maculopathy, and at 28 years, an acute cardiac decompensation without any premise. Blood individual acylcarnitine analysis showed a rise in hydroxylated long-chain fatty acids and fluxomic studies validated enzyme blockade consistent with LCHADD. Genetic analysis revealed the common p.(Glu510Gln) variant in HADHA, in trans with a novel variant c.1108G > A, p.(Gly370Arg) located in the NAD binding domain. Patient pathology was responsive to triheptanoin supplementation.

Conclusion

This atypical LCHADD form report should encourage the early assessment of biochemical and genetic testing as a specific management is recommended (combination with fast avoidance, low fat-high carbohydrate diet, medium-even-chain triglycerides or triheptanoin supplementation).

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Mild hyperpigmented macular dots could be the first and early symptom of moderate LCHAD.

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The novel HADHA c.1108G > A, p.(Gly370Arg) is hypomorphic and associated with moderate LCHAD.

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Atypical and late LCHAD can be deciphered by joint biochemical and genetical investigations.

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Acylcarnitines must be tested in unexplained macular dystrophy and/or dilated cardiomyopathy.

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Supplementation with the triglyceride triheptanoin is effective.

Analysis of clinical characteristics and genetic testing in patients with acute fatty liver of pregnancy: a retrospective study

Background

Acute fatty liver of pregnancy (AFLP) is an acute, rare and potentially lethal disease typically occurring in the third trimester of pregnancy. So far, there is no effective means of prevention. Therefore, in this study, we retrospectively analyzed the clinical features of AFLP patients for a better understanding. Meanwhile, for the first time, the genetic background associated with the onset of AFLP was discussed by high-throughput sequencing, hoping to provide evidence for genetic counseling and prenatal diagnosis of AFLP.

Methods

Thirteen AFLP patients admitted to our hospital and other hospital from March 2012 to February 2020 were selected. Clinical data about general condition, laboratory test, liver biopsy and the prognosis of mother and fetus were collected for retrospective analysis. In addition, the peripheral blood of five patients with AFLP and one newborn infant of his mother with AFLP was sequenced with whole-exome sequencing and gene mutation was analyzed by bioinformatics methods.

Results

The initial symptoms of AFLP varied differently, with jaundice (9/13, 69%), fatigue (8/13, 62%) and nausea and vomiting (6/13, 46%) being the most common. Moreover, the main maternal complications were coagulopathy (13/13, 100%), followed by acute renal dysfunction (10/13, 77%). Raised serum bilirubin, transaminases and uric acid were found in all patients (100%), hypoglycemia was found in six patients (46%) and fatty liver on ultrasound was seen in five patients (5/12, 42%). One (7%) maternal death occurred and all neonates survived delivery. In addition, to our surprise, whole-exome sequencing showed that no gene mutation in related enzymes involved in fatty acid metabolism was noted in the pregnant women and children receiving genetic testing.

Conclusions

Early visit, early detection, early termination of pregnancy and multidisciplinary comprehensive treatment are the key factors to improve the prognosis of AFLP patients and their newborn infants. Furthermore, although limited size of study, to our knowledge, this report is the first to present the lack of common mutation involved in fatty acid oxidation in Chinese patients with AFLP via whole-exome sequencing. Thus, further studies are needed with larger and more varied samples to validate the conclusion.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-04095-8.

Liver disease in pregnancy: Medical aspects and their implications for mother and child

Liver disease during pregnancy is more common than expected and may require specialized intervention. It is important to determine if changes in liver physiology may develop into liver disease, to assure early diagnosis. For adequate surveillance of mother-fetus health outcome, liver disease during pregnancy might require intervention from a hepatologist. Liver diseases have a prevalence of at least 3% of all pregnancies in developed countries, and they are classified into two main categories: related to pregnancy; and those non- related that are present de novo or are preexisting chronic liver diseases. In this review we describe and discuss the main characteristics of those liver diseases associated with pregnancy and only some frequent pre-existing and co-incidental in pregnancy are considered. In addition to the literature review, we compiled the data of liver disease occurring during pregnancies attended at the National Institute of Perinatology in Mexico City in a three-year period. In our tertiary referral women hospital, liver disease was present in 11.24 % of all pregnancies. Associated liver disease was found in 10.8% of all pregnancies, mainly those related to pre-eclampsia (9.9% of pregnancies). Only 0.56% was due to liver disease that was co-incidental or preexisting; the acute or chronic hepatitis C virus was the most frequent in this group (0.12%). When managing pregnancy in referral hospitals in Latin America, it is important to discard liver alterations early for adequate follow up of the disease and to prevent adverse consequences for the mother and child.

Risk factors assessment in patients with acute fatty liver of pregnancy treated without plasma exchange or renal replacement therapy

Objective: Acute fatty liver of pregnancy(AFLP) is a rare but very urgent obstetric disease in clinical. It is a common cause of liver failure in pregnancy and often needs to be admitted to the department of critical care medicine because of the rapid development of acute hepatic dysfunction and severe acute renal dysfunction. The etiology and pathogenesis of this disorder is not very clear although there have been many studies on it before. Meanwhile, the relatively high mortality requires a better recognition in order to better guide clinical decision making. Our previous multicentre retrospective study on AFLP demonstrated that total bilirubin and serum creatinine were independent risk factors for perinatal maternal mortality. And we aim to further assess maternal outcomes and risk factors in AFLP patients treated without plasma exchange or renal replacement therapy based on previous data we collected.Methods: Retrospective cohort study of 133 hospitalized patients with AFLP was collected from four Chinese tertiary hospitals during the period between January 2009 and April 2014. One hundred thirty three patients were divided into two subgroups containing patients treated without plasma exchange (PE) or renal replacement therapy (CRT) and patients treated with PE or/and CRT. Logistic regression was used to analyze independent risk factors for maternal mortality of AFLP treated without PE or CRT.Results: The maternal mortality rate was 12.0% in subgroup of patients treated without PE or CRT. And in subgroup of patients treated with PE or/and CRT, the maternal mortality rate was 26.8%. Independent risk factors for maternal mortality of AFLP treated without PE or CRT were direct bilirubin (OR = 1.012; 95% CI, 1.002-1.022) and serum creatinine (OR = 1.022; 95% CI, 1.007-1.036).Conclusion: Although less liver and kidney damage in AFLP treated without PE or CRT, direct bilirubin and serum creatinine remained to be independent risk factors for maternal mortality. Thus, the level of bilirubin and serum creatinine might not be necessary for AFLP to decide whether to give plasma exchange or dialysis treatment.

Depleted mitochondrial DNA content in peripheral blood of women with a history of HELLP syndrome

OBJECTIVE

To test the hypothesis that a quantitative defect of maternal cellular mitochondria would play a role in the pathogenesis of HELLP syndrome.

STUDY DESIGN

Peripheral blood mitochondrial DNA (MtDNA) was measured in 20 non-pregnant women with a history of HELLP syndrome, 40 non-pregnant control subjects who had previous physiologic pregnancies, 59 subjects carrying physiologic pregnancies, seven pregnant women with a history of HELLP syndrome and five women in the active phase of the disease.

MAIN OUTCOME MEASURE

Peripheral blood Mt-DNA.

RESULTS

The median (interquartile range) mtDNA in women with a history of HELLP syndrome, in non-pregnant women who had previous physiologic pregnancies, in subjects carrying physiologic pregnancies, in pregnant women with a history of HELLP syndrome and in women in the active phase of the disease was 115 (81-194), 229 (199-319), 174 (136-211), 101 (82-178) and 92 (39-129) copies per nuclear DNA, respectively. Non-pregnant women with a history of HELLP syndrome had significantly lower levels than non-pregnant controls (p<0.001). Moreover, blood mtDNA was lower in pregnant women with a history of HELLP syndrome and in those in the active phase of the disease when compared to pregnant controls (p=0.002 and p=0.025, respectively).

CONCLUSIONS

Attenuated maternal mitochondrial function may favor HELLP syndrome development.

Retrospective analysis of acute fatty liver of pregnancy: twenty-eight cases and discussion of anesthesia

AIMS

To summarize the clinical features, perioperative management and maternal and neonatal outcomes of patients with acute fatty liver of pregnancy (AFLP) and to discuss the management of anesthesia in these patients.

METHODS

This study was a retrospective review over a period of 5 years and 9 months; 28 cases from the Shanghai Public Health Clinical Center were included. Records were reviewed for symptoms, signs, laboratory findings, clinical courses, perioperative management and maternal and neonatal outcomes.

RESULTS

Of the AFLP cases analyzed in the present study, 75.0% occurred in primipara and 63.3% occurred with male fetuses. Prodromic symptoms included the sudden onset of fatigue, nausea, vomiting, anorexia and jaundice. Laboratory results indicated liver function abnormalities, coagulopathy, hypoglycemia, leukocytosis and negative urine bilirubin. There were 2 maternal deaths (7.1%) without fetal deaths. Cesarean sections were performed in 16 cases under neuraxial anesthesia and in 12 cases under general anesthesia with rapid-sequence induction.

CONCLUSION

Early diagnosis, prompt delivery and intensive supportive treatment are critical for improving the prognosis of AFLP. Anesthesia selection should be individualized and general anesthesia with rapid-sequence induction may be the best choice for patients with severe coagulopathy.

Next-generation sequencing for mitochondrial diseases: a wide diagnostic spectrum

BACKGROUND

The current diagnostic approach for mitochondrial disorders requires invasive procedures such as muscle biopsy and multiple biochemical testing but the results are often inconclusive. Clinical sequencing tests are available only for a limited number of genes. Recently, massively parallel sequencing has become a powerful tool for testing genetically heterogeneous conditions such as mitochondrial disorders.

METHODS

Targeted next-generation sequencing was performed on 26 patients with known or suspected mitochondrial disorders using in-solution capture for the exons of 908 known and candidate nuclear genes and an Illumina genome analyzer.

RESULTS

None of the 18 patients with various abnormal respiratory chain complex (RCC) activities had molecular defects in either subunits or assembly factors of mitochondrial RCC enzymes except a reference control sample with known mutations in SURF1. Instead, several variants in known pathogenic genes including CPT2, POLG, PDSS1, UBE3A, SDHD, and a few potentially pathogenic variants in candidate genes such as MTO1 or SCL7A13 were identified.

CONCLUSIONS

Sequencing only nuclear genes for RCC subunits and assembly factors may not provide the diagnostic answers for suspected patients with mitochondrial disorders. The present findings indicate that the diagnostic spectrum of mitochondrial disorders is much broader than previously thought, which could potentially lead to misdiagnosis and/or inappropriate treatment. Overall analytic sensitivity and precision appear acceptable for clinical testing. Despite the limitations in finding mutations in all patients, the present findings underscore the considerable clinical benefits of targeted next-generation sequencing and serve as a prototype for extending the clinical evaluation in this clinically heterogeneous patient group.

Liver injury in acute fatty liver of pregnancy: possible link to placental mitochondrial dysfunction and oxidative stress

Acute fatty liver of pregnancy (AFLP) is a rare disorder which is fatal if not recognized and treated early. Delivery of the feto-placental unit results in dramatic improvement in maternal liver function, suggesting a role for the placenta. However, the mechanisms by which defects in the fetus or placenta lead to maternal liver damage are not well understood and form the focus of this study. Placenta and serum were obtained at delivery from patients with AFLP, and placental mitochondria and peroxisomes were isolated. Placental mitochondrial function, oxidative stress, and fatty acid composition as well as serum antioxidants, oxidative and nitrosative stress markers, and fatty acid analysis were carried out. Hepatocytes in culture were used to evaluate cell death, mitochondrial function, and lipid accumulation on exposure to fatty acids. Oxidative stress was evident in placental mitochondria and peroxisomes of patients with AFLP, accompanied by compromised mitochondrial function. Increased levels of arachidonic acid were also seen in AFLP placenta when compared to control. Patients with AFLP also had a significant increase in oxidative and nitrosative stress markers in serum, along with decreased antioxidant levels and elevated levels of arachidonic acid. These levels of arachidonic acid were capable of inducing oxidative stress in hepatocyte mitochondria accompanied by induction of apoptosis. Exposure to arachidonic acid also resulted in increased lipid deposition in hepatocytes.

CONCLUSION

Oxidative stress in placental mitochondria and peroxisomes is accompanied by accumulation of toxic mediators such as arachidonic acid, which may play a causative role in maternal liver damage seen in AFLP.

Genes and the preeclampsia syndrome

Preeclampsia is specific to pregnancy and is still a leading cause of maternal and perinatal mortality and morbidity, affecting about 3% of women, but the underlying pathogenetic mechanisms still remain unclear. Immune maladaptation, placental ischemia and increased oxidative stress represent the main components discussed to be of etiologic importance, and they all may have genetic implications. Since the familial nature of preeclampsia is known for many years, extensive research on the genetic contribution to the pathogenesis of this severe pregnancy disorder has been performed. In this review, we will overview the linkage and candidate gene studies carried out so far as well as summarize important historical notes on the genetic hypotheses generated in preeclampsia research. Moreover, the influence of maternal and fetal genes and their interaction as well as the role of genomic imprinting in preeclampsia will be discussed.

Highly active antiretroviral therapy does not affect mitochondrial beta-oxidation of fatty acids: an in vitro study in fibroblasts

Preeclampsia is a multifactorial pregnancy-specific disease. In some cases, severe preeclampsia and related disorders of acute fatty liver of pregnancy and hemolysis, elevated liver enzymes, low platelets syndrome are associated with inherited defects in mitochondrial beta-oxidation of fatty acids, especially a deficiency of long-chain 3-hydroxyacyl coenzyme A dehydrogenase (LCHAD). Recently, an unexplained increase in the incidence of preeclampsia has been documented in human immunodeficiency virus (HIV)-infected pregnant women on treatment with highly active antiretroviral therapy (HAART). We performed this study to determine if antiretroviral drugs affect mitochondrial beta-oxidation fatty acids in vitro. Two normal and 1 heterozygous LCHAD-deficient cell lines were exposed to up to 5 times the therapeutic concentrations of the following antiretroviral drugs: nevirapine, didanosine, lamivudine, and a combination of nelfinavir, zidovudine, and lamivudine. One homozygous LCHAD-deficient cell line served as the positive control. After exposure of the fibroblasts to these drugs for periods ranging from 2 to 10 days, accumulations of even-chain 3-hydroxy fatty acids (3-OH-C6 to 3-OH-C18) in the culture media were measured by stable-isotope dilution gas chromatography/mass spectrometry. Compared to the respective unexposed fibroblasts, there was no significant build-up of 3-hydroxy fatty acids in the culture media of normal or heterozygous LCHAD-deficient fibroblasts exposed to antiretroviral drugs. Our results show that the commonly used antiretroviral drugs do not adversely affect fatty acid oxidation in fibroblasts. Therefore, an altered fatty acid oxidation may not be the mechanism for the reported increased risk of preeclampsia in HIV-infected pregnant women on HAART.

Neither maternal nor fetal mutation (E474Q) in the alpha-subunit of the trifunctional protein is frequent in pregnancies complicated by HELLP syndrome

OBJECTIVE

An association between maternal HELLP syndrome and fetal long chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency has been proposed. LCHAD catalyzes the third step in the beta-oxidation of fatty acids in mitochondria. Whereas about 75% of LCHAD-deficient patients carry a G-to-C mutation at nucleotide position 1528 (Glu474Gln, E474Q) on both chromosomes, compound heterozygosity for E474Q on one chromosome and a second different LCHAD mutation on the other can be observed in up to 25% of LCHAD-deficiency cases; only very few patients carry two mutations different from E474Q. Genetic analysis of the mother alone is insufficient in case of compound heterozygosity. Since information on the fetal carrier status of the E474Q mutation in maternal HELLP syndrome is rare, we investigated the frequency of the E474Q mutation in families where the mother had HELLP syndrome.

METHODS

The occurrence of the E474Q mutation was analyzed by PCR and RFLP in 103 mothers with HELLP syndrome, in 82 children of affected pregnancies and in 21 fathers in families where fetal DNA was not available. In addition, 103 control women with only uncomplicated pregnancies were investigated.

RESULTS

The mutation E474Q was not detected in the study population.

CONCLUSION

Neither maternal nor fetal heterozygosity for the E474Q mutation is a relevant factor of HELLP syndrome.