Pharmacovigilance pregnancy data in a large population of patients with chronic inflammatory disease exposed to certolizumab pegol.

Introduction: Chronic inflammatory diseases (CIDs), including rheumatic diseases and other inflammatory conditions, often affect women of reproductive age. Tumor necrosis factor inhibitors (TNFi) are widely used to treat CID, but there is limited information on outcomes of TNFi-exposed pregnancies. We evaluated pregnancy outcomes from 1392 prospectively reported pregnancies exposed to certolizumab pegol (CZP), a PEGylated, Fc-free TNFi with no to minimal placental transfer. Methods: CZP-exposed pregnancies in patients with CID from the UCB Pharmacovigilance global safety database were reviewed from the start of CZP clinical development (July 2001) to 1 November 2020. To limit bias, the analysis focused on prospectively reported cases with known pregnancy outcomes. Results: In total, 1392 prospective pregnancies with maternal CZP exposure and known pregnancy outcomes (n = 1425) were reported; 1021 had at least first-trimester CZP exposure. Live birth was reported in 1259/1425 (88.4%) of all prospective outcomes. There were 150/1425 (10.5%) pregnancy losses before 20 weeks (miscarriage/induced abortion), 11/1425 (0.8%) stillbirths, and 5/1392 (0.4%) ectopic pregnancies. Congenital malformations were present in 30/1259 (2.4%) live-born infants, of which 26 (2.1%) were considered major according to the Metropolitan Atlanta Congenital Defects Program criteria. There was no pattern of congenital malformations. Discussion and conclusion: No signal for adverse pregnancy outcomes or congenital malformations was observed in CZP-exposed pregnancies. Although the limitations of data collected through this methodology (including underreporting, missing information, and absence of a comparator group) should be considered, these data provide reassurance for women with CID who require CZP treatment during pregnancy, and their treating physicians.

Clinical Exome Studies Have Inconsistent Coverage.

BACKGROUND: Exome sequencing has become a commonly used clinical diagnostic test. Multiple studies have examined the diagnostic utility and individual laboratory performance of exome testing; however, no previous study has surveyed and compared the data quality from multiple clinical laboratories. METHODS: We examined sequencing data from 36 clinical exome tests from 3 clinical laboratories. Exome data were compared in terms of overall characteristics and coverage of specific genes and nucleotide positions. The sets of genes examined included genes in Consensus Coding Sequence (CCDS) (n = 17723), a subset of genes clinically relevant to epilepsy (n = 108), and genes that are recommended for reporting of secondary findings (n = 57; excludes X-linked genes). RESULTS: The average exome nucleotide coverage (≥20×) of each laboratory varied at 96.49% (CV = 3%), 96.54% (CV = 1%), and 91.68% (CV = 4%), for laboratories A, B, and C, respectively. For CCDS genes, the average number of completely covered genes varied at 12184 (CV = 29%), 11687 (CV = 13%), and 5989 (CV = 37%), for laboratories A, B, and C, respectively. With smaller subsets of genes related to epilepsy and secondary findings, the CV revealed low consistency, with a maximum CV seen in laboratory C for both epilepsy genes (CV = 60%) and secondary findings genes (CV = 71%). CONCLUSIONS: Poor consistency in complete gene coverage was seen in the clinical exome laboratories surveyed. The degree of consistency varied widely between the laboratories.

Association Between Birth Defects and Cancer Risk Among Children and Adolescents in a Population-Based Assessment of 10 Million Live Births.

IMPORTANCE: Birth defects affect approximately 1 in 33 children. Some birth defects are known to be strongly associated with childhood cancer (eg, trisomy 21 and acute leukemia). However, comprehensive evaluations of childhood cancer risk in those with birth defects have been limited in previous studies by insufficient sample sizes. OBJECTIVES: To identify specific birth defect-childhood cancer (BD-CC) associations and characterize cancer risk in children by increasing number of nonchromosomal birth defects. DESIGN, SETTING, AND PARTICIPANTS: This multistate, population-based registry linkage study pooled statewide data on births, birth defects, and cancer from Texas, Arkansas, Michigan, and North Carolina on 10 181 074 children born from January 1, 1992, to December 31, 2013. Children were followed up to 18 years of age for a diagnosis of cancer. Data were retrieved between September 26, 2016, and September 21, 2017, and data analysis was performed from September 2, 2017, to March 21, 2019. EXPOSURES: Birth defects diagnoses (chromosomal anomalies and nonchromosomal birth defects) recorded by statewide, population-based birth defects registries. MAIN OUTCOMES AND MEASURES: Cancer diagnosis before age 18 years, as recorded in state cancer registries. Cox regression models were used to generate hazard ratios (HRs) and 95% CIs to evaluate BD-CC associations and the association between number of nonchromosomal defects and cancer risk. RESULTS: Compared with children without any birth defects, children with chromosomal anomalies were 11.6 (95% CI, 10.4-12.9) times more likely to be diagnosed with cancer, whereas children with nonchromosomal birth defects were 2.5 (95% CI, 2.4-2.6) times more likely to be diagnosed with cancer before 18 years of age. An increasing number of nonchromosomal birth defects was associated with a corresponding increase in the risk of cancer. Children with 4 or more major birth defects were 5.9 (95% CI, 5.3-6.4) times more likely to be diagnosed with cancer compared with those without a birth defect. In the analysis of 72 specific BD-CC patterns, 40 HRs were statistically significant (adjusted P < .05) after accounting for multiple comparisons. Cancers most frequently associated with nonchromosomal defects were hepatoblastoma and neuroblastoma. CONCLUSIONS AND RELEVANCE: Several significant and novel associations were observed between specific birth defects and cancers. Among children with nonchromosomal birth defects, the number of major birth defects diagnosed was significantly and directly associated with cancer risk. These findings could inform clinical treatment for children with birth defects and may elucidate mechanisms that lead to these complex outcomes.

Incontinentia pigmenti in adults.

Incontinentia Pigmenti (IP; MIM 308300) is an X-linked dominant genodermatosis caused by pathogenic variant in IKBKG. The phenotype in adults is poorly described compared to that in children. Questionnaire survey of 99 affected women showed an age at diagnosis from newborn to 41 years, with 53 diagnosed by 6 months of age and 30 as adults. Stage I, II, and III lesions persisted in 16%, 17%, and 71%, respectively, of those who had ever had them. IP is allelic to two forms of ectodermal dysplasia. Many survey respondents reported hypohidrosis and/or heat intolerance and most had Stage IV findings. This suggests that "Stage IV" may be congenitally dysplastic skin that becomes more noticeable with maturity. Fifty-one had dentures or implants with 26 having more invasive jaw or dental surgery. Half had wiry or uncombable hair. Seventy-three reported abnormal nails with 27 having long-term problems. Cataracts and retinal detachment were the reported causes of vision loss. Four had microphthalmia. Respondents without genetic confirmation of IP volunteered information suggesting more involved phenotype or possibly misassigned diagnosis. Ascertainment bias likely accounts for the low prevalence of neurocognitive problems in the respondents.

Selected acculturation factors and birth defects in the National Birth Defects Prevention Study, 1997-2011.

BACKGROUND: Acculturation has been examined with respect to various pregnancy adverse outcomes, including birth defects. Given the mixed and limited findings on the association between nativity and birth defects, we sought to further explore parental nativity and years lived in the U.S. across a range of defects. METHODS: Data from the National Birth Defects Prevention Study were used for this analysis. Infants with one of 46 major isolated birth defects (30 noncardiac/16 cardiac conditions) and infants without birth defects (controls) born during 1997-2011 were included. We examined parental nativity (foreign-born mothers, fathers, and both parents combined compared to a referent of both U.S.-born parents) and the number of years lived in the U.S. (≤5/6+ years). Descriptive statistics and logistic regression analyses were performed to estimate crude/adjusted odds ratios and 95% confidence intervals. RESULTS: Compared to U.S.-born mothers, foreign-born mothers tended to be older (25+ years), of Hispanic or Other race/ethnicity and were less likely to have reported drinking, smoking, illicit drug use, or having taken folic acid. In the adjusted analysis, seven findings among both parents reporting a foreign-birth were significant, including an increased association with spina bifida, anotia/microtia, and diaphragmatic hernia (aORs range: 1.3-1.7), and a reduced association with craniosynostosis and gastroschisis (aORs = 0.7). A generally protective effect was observed among foreign-born subjects living in the U.S. ≤5 years. CONCLUSIONS: We found that nativity was associated with some selected isolated defects, although the direction of effect varied by phenotype and by a number of years residing in the U.S.

An additional case of Hennekam lymphangiectasia-lymphedema syndrome caused by loss-of-function mutation in ADAMTS3.

Hennekam lymphangiectasia-lymphedema syndrome (HKLLS) is a genetically heterogeneous lymphatic dysplasia with characteristic of facial dysmorphism, neurocognitive impairments, and abnormalities of the pericardium, intestinal tract, and extremities. It is an autosomal recessive condition caused by biallelic mutations in CCBE1 (collagen- and calcium-binding epidermal growth factor domain-containing protein 1) (HKLLS1; OMIM 235510) or FAT4 (HKLLS2; OMIM 616006). CCBE1 acts via ADAMTS3 (a disintegrin and metalloprotease with thrombospondin motifs-3 protease) to enhance vascular endothelial growth factor C signaling. There is report of one family supporting mutations in ADAMTS3 as causative for the phenotype labeled as HKLLS3. Here, we report an additional case of HKLLS that appears to be associated with homozygous nonsense mutation of ADAMTS3.

Expanding the clinical and molecular findings in RASA1 capillary malformation-arteriovenous malformation.

RASA1-related disorders are vascular malformation syndromes characterized by hereditary capillary malformations (CM) with or without arteriovenous malformations (AVM), arteriovenous fistulas (AVF), or Parkes Weber syndrome. The number of cases reported is relatively small; and while the main clinical features are CMs and AVMs/AVFs, the broader phenotypic spectrum caused by variants in the RASA1 gene is still being defined. Here, we report the clinical and molecular findings in 69 unrelated cases with a RASA1 variant identified at ARUP Laboratories. Sanger sequencing and multiplex ligation-dependent probe amplification were primarily used to evaluate RASA1. Several atypical cases were evaluated using next-generation sequencing (NGS) and array-comparative genomic hybridization (aCGH). Sixty individuals had a deleterious RASA1 variant of which 29 were novel. Nine individuals had a variant of uncertain significance. Five large RASA1 deletions were detected, giving an overall deletion/duplication rate of 8.3% (5/60) among positive cases. Most (75.4%) individuals with a RASA1 variant had CMs, and 44.9% had an AVM/AVF. Clinical findings in several cases expand the RASA1 phenotype. Our data suggest that screening for large RASA1 deletions and duplications in this disorder is important and suggest that NGS multi-gene panel testing is beneficial for the molecular diagnosis of cases with complex vascular phenotypes.

Pregnancy Outcomes After Exposure to Certolizumab Pegol: Updated Results From a Pharmacovigilance Safety Database.

OBJECTIVE: Anti-tumor necrosis factor (anti-TNF) medications are effective in controlling chronic inflammatory diseases, but information about their use and safety in pregnancy is limited. Consequently, anti-TNF agents are often discontinued early in gestation. Certolizumab pegol (CZP), a PEGylated, Fc-free anti-TNF agent approved for the treatment of rheumatic diseases and/or Crohn's disease, has minimal to no active placental transfer. This analysis was undertaken to evaluate pregnancy outcomes in women receiving CZP, especially those exposed during early pregnancy. METHODS: Prospective and retrospective data on maternal CZP exposure were extracted from the UCB Pharma safety database through March 6, 2017. Analysis was limited to prospective reports to avoid potential bias associated with retrospective submissions. The numbers of live births, miscarriages, elective abortions, stillbirths, and major congenital malformations were ascertained. RESULTS: Of 1,137 prospectively reported pregnancies with maternal exposure to CZP, 528 (including 10 twin pregnancies) had 538 known outcomes: 459 live births (85.3%), 47 miscarriages (8.7%), 27 elective abortions (5.0%), and 5 stillbirths (0.9%). There were 8 major congenital malformations (1.7%) among the 459 infants. First trimester exposure occurred in 367 (81.2%) of 452 pregnancies resulting in 459 live births. Exposure during all 3 trimesters occurred in 201 (44.5%) of 452 pregnancies. CONCLUSION: This analysis represents the largest cohort of pregnant women exposed to an anti-TNF agent for management of chronic inflammatory diseases. Analysis of pregnancy outcomes does not indicate a teratogenic effect of CZP, compared to the general population, nor an increased risk of fetal death. The data are reassuring for women of childbearing age considering treatment with CZP.

Pre-Zika descriptive epidemiology of microcephaly in Texas, 2008-2012.

BACKGROUND: There are limited population-based studies on microcephaly. We characterized the epidemiology of microcephaly in Texas during a 5-year period (2008-2012), prior to the Zika epidemic in the Western hemisphere (2015). The associations of suspected risk factors were compared across four clearly defined case groups. METHODS: Data from the Texas Birth Defects Registry were used to calculate the prevalence of congenital microcephaly and crude and adjusted prevalence ratios using Poisson regression. Twelve maternal and infant factors were assessed across case groups, which included total (explained + unexplained), explained (e.g., syndromic), unexplained, and severe unexplained microcephaly (head circumference <3rd percentile). RESULTS: The birth prevalence for total and total severe microcephaly were 14.7 and 4.8 per 10,000 livebirths, respectively. For explained and unexplained cases, significantly elevated risks were noted for mothers who were older (35+), less educated (≤12 years), diabetic (pre-pregnancy or gestational), or had a preterm delivery. Unlike explained cases, however, mothers who were non-White or smoked had an increased risk for unexplained microcephaly. Furthermore, young maternal age (<20), multiparity, and higher BMI reduced the risk for unexplained microcephaly. For severe unexplained cases, the risk profile was similar to that for all unexplained cases-with the exception of null associations noted for diabetes and birth year. CONCLUSIONS: We found that risk patterns for microcephaly varied across case groupings. Risk factors included maternal race/ethnicity, age, and smoking during pregnancy. Among severe unexplained cases, notable positive associations were seen among mothers who were non-Hispanic Black or less educated, while inverse associations were noted for obesity.

Enamel Pit Defects and Taurodontism in a Patient with Ring Chromosome 14 and 47,XXX.

The purpose of this paper is to describe the clinical findings and management of a case involving a patient with co-occurring ring chromosome 14 syndrome and 47,XXX presenting with enamel pit defects and taurodontism. Ring chromosome 14 syndrome is an unusual condition with uncontrolled seizure disorder as its most significant finding; 47,XXX (trisomy X; triple X) is a more common condition and has characteristic physical and behavioral findings. Neither condition has been associated with enamel pit defects.

Mandibulofacial Dysostosis with Microcephaly: Mutation and Database Update.

Mandibulofacial dysostosis with microcephaly (MFDM) is a multiple malformation syndrome comprising microcephaly, craniofacial anomalies, hearing loss, dysmorphic features, and, in some cases, esophageal atresia. Haploinsufficiency of a spliceosomal GTPase, U5-116 kDa/EFTUD2, is responsible. Here, we review the molecular basis of MFDM in the 69 individuals described to date, and report mutations in 38 new individuals, bringing the total number of reported individuals to 107 individuals from 94 kindreds. Pathogenic EFTUD2 variants comprise 76 distinct mutations and seven microdeletions. Among point mutations, missense substitutions are infrequent (14 out of 76; 18%) relative to stop-gain (29 out of 76; 38%), and splicing (33 out of 76; 43%) mutations. Where known, mutation origin was de novo in 48 out of 64 individuals (75%), dominantly inherited in 12 out of 64 (19%), and due to proven germline mosaicism in four out of 64 (6%). Highly penetrant clinical features include, microcephaly, first and second arch craniofacial malformations, and hearing loss; esophageal atresia is present in an estimated ∼27%. Microcephaly is virtually universal in childhood, with some adults exhibiting late "catch-up" growth and normocephaly at maturity. Occasionally reported anomalies, include vestibular and ossicular malformations, reduced mouth opening, atrophy of cerebral white matter, structural brain malformations, and epibulbar dermoid. All reported EFTUD2 mutations can be found in the EFTUD2 mutation database (http://databases.lovd.nl/shared/genes/EFTUD2).

De novo mutations in NALCN cause a syndrome characterized by congenital contractures of the limbs and face, hypotonia, and developmental delay.

Freeman-Sheldon syndrome, or distal arthrogryposis type 2A (DA2A), is an autosomal-dominant condition caused by mutations in MYH3 and characterized by multiple congenital contractures of the face and limbs and normal cognitive development. We identified a subset of five individuals who had been putatively diagnosed with "DA2A with severe neurological abnormalities" and for whom congenital contractures of the limbs and face, hypotonia, and global developmental delay had resulted in early death in three cases; this is a unique condition that we now refer to as CLIFAHDD syndrome. Exome sequencing identified missense mutations in the sodium leak channel, non-selective (NALCN) in four families affected by CLIFAHDD syndrome. We used molecular-inversion probes to screen for NALCN in a cohort of 202 distal arthrogryposis (DA)-affected individuals as well as concurrent exome sequencing of six other DA-affected individuals, thus revealing NALCN mutations in ten additional families with "atypical" forms of DA. All 14 mutations were missense variants predicted to alter amino acid residues in or near the S5 and S6 pore-forming segments of NALCN, highlighting the functional importance of these segments. In vitro functional studies demonstrated that NALCN alterations nearly abolished the expression of wild-type NALCN, suggesting that alterations that cause CLIFAHDD syndrome have a dominant-negative effect. In contrast, homozygosity for mutations in other regions of NALCN has been reported in three families affected by an autosomal-recessive condition characterized mainly by hypotonia and severe intellectual disability. Accordingly, mutations in NALCN can cause either a recessive or dominant condition characterized by varied though overlapping phenotypic features, perhaps based on the type of mutation and affected protein domain(s).

Sociodemographic and hispanic acculturation factors and isolated anotia/microtia.

BACKGROUND: It has been observed in several studies that infants with anotia/microtia are more common among Hispanics compared with other racial/ethnic groups. We examined the association between selected Hispanic ethnicity and acculturation factors and anotia/microtia in the National Birth Defects Prevention Study. METHODS: We examined data from mothers of 351 infants with isolated anotia/microtia and 8435 unaffected infants from the National Birth Defects Prevention Study with an expected delivery date from 1997 to 2007. Sociodemographic, maternal, and acculturation factors (e.g., age, maternal education, household income, body mass index, gestational diabetes, folic acid, smoking, alcohol intake, study center, parental birthplace, and years lived in the United States, maternal language) were assessed as overall risk factors and also as risk factors among subgroups of Hispanics (United States- and foreign-born) versus non-Hispanic whites. RESULTS: Compared with non-Hispanic whites, both United States- and foreign-born Hispanic mothers demonstrated substantially higher odds of delivering infants with anotia/microtia across nearly all strata of sociodemographic and other maternal factors (adjusted odds ratios range: 2.1-11.9). The odds of anotia/microtia was particularly elevated among Hispanic mothers who emigrated from Mexico after age five (adjusted odds ratios = 4.88; 95% confidence interval = 2.93-8.11) or who conducted the interview in Spanish (adjusted odds ratios = 4.97; 95% confidence interval = 3.00-8.24). CONCLUSION: We observed that certain sociodemographic and acculturation factors are associated with higher risks of anotia/microtia among offspring of Hispanic mothers.

Birth defects, causal attributions, and ethnicity in the national birth defects prevention study.

In order to translate research findings into effective prevention strategies, it is important to understand people's beliefs about the causes of poor health outcomes. However, with the exception of knowledge and beliefs about folic acid supplementation, little is known regarding women's causal attributions women regarding birth defects. We employed Attribution Theory constructs to analyze open-text interview responses from 2,672 control mothers in the National Birth Defects Prevention Study who gave birth in 1997-2005. Common themes included use of alcohol, tobacco, illicit drugs, and medications during pregnancy. Stress and emotional upset were also suggested as possible causes of birth defects. Genetic- and heredity-related responses were more likely to be mentioned by Asian/Pacific Islander women compared to non-Hispanic Whites. Hispanic women were less likely to suggest several specific possible teratogens, such as paint, pesticides, or other chemicals, but were more likely to suggest events occurring during childbirth. Differences also emerged among ethnic groups for theoretical constructs, although most responses were categorized as controllable, changeable over time, and with an internal locus of causality.

Descriptive epidemiology of selected heritable birth defects in Texas.

BACKGROUND: Few population-based studies exist on descriptive epidemiologic characteristics of rare heritable birth defects. The number of birth defect cases in the Texas Birth Defects Registry (one of the largest active birth defects surveillance systems in the world) enabled us to examine six different heritable disorders (aqueductal stenosis, infantile polycystic kidney disease, achondroplasia, thanatophoric dwarfism, chondrodysplasia/dwarfism not otherwise specified (NOS), and osteogenesis imperfecta) for a variety of descriptive demographic variables. METHODS: The Texas Birth Defects Registry was used to identify infants or fetuses with heritable birth defects. Crude prevalence rates were calculated and Poisson regression was used to test the association of each demographic variable (e.g., maternal age) with each of the selected genetic birth defects. RESULTS: White non-Hispanics exhibited higher rates of achondroplasia and osteogenesis imperfecta than other race/ethnic groups. Lower maternal education level and to a lesser extent, paternal education level, was associated with higher rates of several disorders. The birth prevalence rate for achondroplasia decreased from 1999 through 2006. CONCLUSION: The use of a large birth defects registry provides a sufficient count of cases to perform some basic epidemiologic analysis on selected rare heritable birth defects.

Alcohol consumption by women before and during pregnancy.

OBJECTIVES: To determine the prevalence, patterns, and predictors of alcohol consumption prior to and during various intervals of pregnancy in the U.S. METHODS: Alcohol-related, pregnancy-related, and demographic data were derived from computer-assisted telephone interviews with 4,088 randomly selected control mothers from the National Birth Defects Prevention Study who delivered live born infants without birth defects during 1997-2002. Alcohol consumption rates and crude and adjusted odds ratios (OR) were calculated. RESULTS: 30.3% of all women reported drinking alcohol at some time during pregnancy, of which 8.3% reported binge drinking (4+ drinks on one occasion). Drinking rates declined considerably after the first month of pregnancy, during which 22.5% of women reported drinking, although 2.7% of women reported drinking during all trimesters of pregnancy and 7.9% reported drinking during the 3rd trimester. Pre-pregnancy binge drinking was a strong predictor of both drinking during pregnancy (adjusted OR = 8.52, 95% CI = 6.67-10.88) and binge drinking during pregnancy (adjusted OR = 36.02, 95% CI = 24.63-52.69). Other characteristics associated with both any drinking and binge drinking during pregnancy were non-Hispanic white race/ethnicity, cigarette smoking during pregnancy, and having an unintended pregnancy. CONCLUSIONS: Our study revealed that drinking during pregnancy is fairly common, three times the levels reported in surveys that ask only about drinking during the month before the survey. Women who binge drink before pregnancy are at particular risk for drinking after becoming pregnant. Sexually active women of childbearing ages who drink alcohol should be advised to use reliable methods to prevent pregnancy, plan their pregnancies, and stop drinking before becoming pregnant.

Neonatal presentation of ventricular tachycardia and a Reye-like syndrome episode associated with disturbed mitochondrial energy metabolism.

BACKGROUND: Hyperammonemia, hypoglycemia, hepatopathy, and ventricular tachycardia are common presenting features of carnitine-acylcarnitine translocase deficiency (Mendelian Inheritance in Man database: *212138), a mitochondrial fatty acid oxidation disorder with a lethal prognosis. These features have not been identified as the presenting features of mitochondrial cytopathy in the neonatal period. CASE PRESENTATION: We describe an atypical presentation of mitochondrial cytopathy in a 2 day-old neonate. She presented with a Reye-like syndrome episode, premature ventricular contractions and ventricular tachycardia. Initial laboratory evaluation exhibited a large amount of 3-methylglutaconic acid on urine organic acid analysis, mild orotic aciduria and a nonspecific abnormal acylcarnitine profile. The evaluation for carnitine-acylcarnitine translocase deficiency and other fatty acid oxidation disorders was negative. The patient later developed a hypertrophic cardiomyopathy and continued to be affected by recurrent Reye-like syndrome episodes triggered by infections. A muscle biopsy exhibited signs of a mitochondrial cytopathy. During the course of her disease, her Reye-like syndrome episodes have subsided; however, cardiomyopathy has persisted along with fatigue and exercise intolerance. CONCLUSIONS: This case illustrates that, in the neonatal period, hyperammonemia and ventricular tachycardia may be the presenting features of a lethal carnitine-acylcarnitine translocase deficiency or of a mitochondrial cytopathy, associated with a milder clinical course. This association broadens the spectrum of presenting phenotypes observed in patients with disturbed mitochondrial energy metabolism. Also, the presence of 3-methylglutaconic aciduria suggests mitochondrial dysfunction and mild orotic aciduria could potentially be used as a marker of mitochondrial disease.