Holt Oram syndrome: a registry-based study in Europe

TBX5 variants and cardiac phenotype: A systematic review of the literature and a novel variant

T-Box Transcription Factor 5 (TBX5) variants are associated with Holt-Oram syndrome. Holt-Oram syndrome display phenotypic variability, regarding upper limb defects, congenital heart defects, and arrhythmias. To investigate the genotype-phenotype relationship between TBX5 variants and cardiac disease, we performed a systematic review of the literature. Through the systematic review we identified 108 variants in TBX5 associated with a cardiac phenotype in 277 patients. Arrhythmias were more frequent in patients with a missense variant (48% vs 30%, p = 0.009) and upper limb abnormalities were more frequent in patients with protein-truncating variants (85% vs 64%, p = 0.0008). We found clustering of missense variants in the T-box domain. Furthermore, we present a family with atrial septal defects. By whole exome sequencing, we identified a novel missense variant p.Phe232Leu in TBX5. The cardiac phenotype included atrial septal defect, arrhythmias, heart failure, and dilated cardiomyopathy. Clinical examination revealed subtle upper limb abnormalities. Thus, the family corresponds to the diagnostic criteria of Holt-Oram syndrome. We provide an overview of cardiac phenotypes associated with TBX5 variants and show an increased risk of arrhythmias associated to missense variants compared to protein-truncating variants. We report a novel missense variant in TBX5 in a family with an atypical Holt-Oram syndrome phenotype.

Genetic syndromes associated with congenital heart disease

Congenital heart defects are the most common type of birth defect, affecting 1% of live births. The underlying cause of congenital heart disease is frequently unknown. However, advances in human genetics and genome technologies have helped expand congenital heart disease pathogenesis knowledge during the last few decades. When the cardiac defects are part of a genetic syndrome, they are associated with extracardiac conditions and require multidisciplinary care and surveillance. Some genetic syndromes can have subtle clinical findings and remain undiagnosed well into adulthood. Each syndrome is associated with specific congenital and acquired comorbidities and a particular clinical risk profile. A timely diagnosis is essential for risk stratification, surveillance of associated conditions and counselling, particularly during family planning. However, genetic testing and counselling indications can be challenging to identify in clinical practice. This document intends to provide an overview of the most clinically relevant syndromes to consider, focusing on the phenotype and genotype diagnosis, outcome data, clinical guidelines and implications for care.

Paternal age and risk for selected birth defects in a large South American sample

BACKGROUND

The relationship between maternal age (MA) and birth defects (BD) has been extensively studied while much less research, mostly with discordant results, has focused on the risk of paternal age (PA) for BD. Furthermore, no consensus has been reached on the best way to control the association of PA with MA.

OBJECTIVES

The aim of the study was to evaluate the risk of PA increase, at 1-year intervals, for selected BD, especially controlling for the confounding effect of MA.

METHODS

The sample comprised of 27,944 liveborns presenting 1 of 18 selected isolated BD. Conditional logistic regressions were applied to evaluate the risk of advanced PA and its yearly increase, adjusting by MA and other variables.

RESULTS

Of the 18 analyzed BD, only the risk for preaxial polydactyly (PreP) showed a significant association with increasing PA, while advanced MA was of low risk. For esophageal and anal atresia, associations with both PA and MA increases were observed.

CONCLUSIONS

Results support the hypothesis of advanced PA as a risk factor for PreP and helps clarify the so far unexplained nonrandom association between this defect and Down syndrome.

Case report: Novel TBX5-related pathogenic mechanism of Holt-Oram syndrome

Introduction: Holt-Oram syndrome (HOS) is a rare genetic disorder characterized by upper limb abnormalities, congenital heart defects, and/or conduction abnormalities. Sequence alteration of T-box transcription factor 5 (TBX5) is correlated with the incidence of HOS. Case description: We present the case of a 24-year-old female with upper limb alterations (congenital dysplasia in the wrist and elbow joints) and an anomalous left main trunk arising from the right coronary sinus. The patient inherited a base T (reference C) at rs883079 from her mother and base C (reference T) at rs10850326 from her father, both of which belong to the 3'-untranslated region (UTR) of the TBX5 gene; no alterations in TBX5 expression or single-nucleotide polymorphisms (SNPs) in other exon areas were found. We explored the effects of TBX5 on cardiomyocytes using the HL-1 cell line and TBX5-knockdown cells. Discussion: Quantitative polymerase chain reaction analysis demonstrated that TEKT2, TEKT4, and SPTB expression decreased after TBX5 knockdown, while chromatin immunoprecipitation analysis further revealed that TBX5 binds to the TEKT2, TEKT4, and SPTB promoter regions to promote gene transcription. Our findings support a novel TBX5-related pathogenic mechanism in HOS.

Tbx5a and Tbx5b paralogues act in combination to control separate vectors of migration in the fin field of zebrafish

The T-box containing family member, TBX5, has been shown to play important functional roles in the pectoral appendages of a variety of vertebrate species. While a single TBX5 gene exists in all tetrapods studied to date, the zebrafish genome retains two paralogues, designated as tbx5a and tbx5b, resulting from a whole genome duplication in the teleost lineage. Zebrafish deficient in tbx5a lack pectoral fin buds, whereas zebrafish deficient in tbx5b exhibit misshapen pectoral fins, showing that both paralogues function in fin development. The mesenchymal cells of the limb/fin bud are derived from the Lateral Plate Mesoderm (LPM). Previous fate mapping work in zebrafish has shown that wildtype (wt) fin field cells are initially located adjacent to somites (s)1-4. The wt fin field cells migrate in opposing diagonal directions placing the limb bud between s2-3 and lateral to the main body. To better characterize tbx5 paralogue functions in zebrafish, time-lapse analyses of the migrations of fin bud precursors under conditions of tbx5a knock-down, tbx5b knock-down and double-knock-down were performed. Our data suggest that zebrafish tbx5a and tbx5b have functionally separated migration direction vectors, that when combined recapitulate the migration of the wt fin field. We and others have shown that loss of Tbx5a function abolishes an fgf24 signaling cue resulting in fin field cells failing to converge in an Antero-Posterior (AP) direction and migrating only in a mediolateral (ML) direction. We show here that loss of Tbx5b function affects initial ML directed movements so that fin field cells fail to migrate laterally but continue to converge along the AP axis. Furthermore, fin field cells in the double Tbx5a/Tbx5b knock-down zebrafish do not engage in directed migrations along either the ML or AP axis. Therefore, these two paralogues may be acting to instruct separate vectors of fin field migration in order to direct proper fin bud formation.

Identification of deleterious single nucleotide polymorphism (SNP)s in the human TBX5 gene & prediction of their structural & functional consequences: An in silico approach

T-box transcription factor 5 gene (TBX5) encodes the transcription factor TBX5, which plays a crucial role in the development of heart and upper limbs. Damaging single nucleotide variants in this gene alter the protein structure, disturb the functions of TBX5, and ultimately cause Holt-Oram Syndrome (HOS). By analyzing the available single nucleotide polymorphism information in the dbSNP database, this study was designed to identify the most deleterious TBX5 SNPs through insilico approaches and predict their structural and functional consequences.

Fifty-eight missense substitutions were found damaging by sequence homology-based tools: SIFT and PROVEAN, and structure homology-based tool PolyPhen-2. Various disease association meta-predictors further scrutinized these SNPs. Additionally, conservation profile of the amino acid residues, their surface accessibility, stability, and structural integrity of the native protein upon mutations were assessed. From these analyses, finally 5 SNPs were detected as the most damaging ones: [rs1565941579 (P85S), rs1269970792 (W121R), rs772248871 (V153D), rs769113870 (E208D), and rs1318021626 (I222N)]. Analyses of stop-lost, nonsense, UTR, and splice site SNPs were also conducted.

Through integrative bioinformatics analyses, this study has identified the SNPs that are deleterious to the TBX5 protein structure and have the potential to cause HOS. Further wet-lab experiments can validate these findings.

•

Deleterious SNPs in the human TBX5 gene responsible for Holt-Oram Syndrome have been identified.

•

58 missense and 2 nonsense SNPs were identified as deleterious.

•

86 3′ UTR SNPs were predicted to be located on miRNA target sites.

•

Possible effects of missense SNPs on the TBX5 protein structure have been studied.

Association between pectus excavatum and congenital genetic disorders: A systematic review and practical guide for the treating physician

BACKGROUND

Pectus excavatum (PE) could be part of a genetic disorder, which then has implications regarding comorbidity, the surgical correction of PE, and reproductive choices. However, referral of a patient presenting with PE for genetic analysis is often delayed because additional crucial clinical signs may be subtle or even missed in syndromic patients. We reviewed the literature to inventory known genetic disorders associated with PE and create a standardized protocol for clinical evaluation.

METHODS

A systematic literature search was performed in electronic databases. Genetic disorders were considered associated with PE if studies reported at least five cases with PE. Characteristics of each genetic disorder were extracted from the literature and the OMIM database in order to create a practical guide for the clinician.

RESULTS

After removal of duplicates from the initial search, 1632 citations remained. Eventually, we included 119 full text articles, representing 20 different genetic disorders. Relevant characteristics and important clinical signs of each genetic disorder were summarized providing a standardized protocol in the form of a scoring list. The most important clinical sign was a positive family history for PE and/or congenital heart defect.

CONCLUSIONS

Twenty unique genetic disorders have been found associated with PE. We have created a scoring list for the clinician that systematically evaluates crucial clinical signs, thereby facilitating decision making for referral to a clinical geneticist.

Combined clinic and home-based therapeutic approach for the treatment of bilateral radial deficiency for a young child with Holt-Oram syndrome: A case report

BACKGROUND

Holt-Oram syndrome (HOS) is a rare, genetic condition characterized by the combination of congenital heart defect and hypoplasia in one or both upper extremities. Children with HOS commonly present with varied joint and limb involvement including radial longitudinal deficiency impacting hand function. Evidence-based guidelines regarding orthotic wear and therapeutic techniques are lacking.

PURPOSE

The aim of this case report was to present the results of a long-term occupational therapy program for a patient with HOS pre and postpollicization.

STUDY DESIGN

Case report.

METHODS

A 4-month-old patient with bilateral radial longitudinal deficiencies began outpatient occupational therapy for custom orthosis fabrication and treatment which included long term clinic and home-based intervention. Techniques included passive range of motion, orthosis wear, therapeutic taping, and modified constraint induced movement therapy. Longitudinal assessment of musculoskeletal alignment and functional hand use was performed using goniometry for passive and active range of motion, the Assisting Hand Assessment (AHA), and The Thumb Grasp and Pinch Assessment (T-GAP).

RESULTS

Improvement in passive and active range of motion was achieved as well as improved activity level function as measured by the AHA and T-GAP postpollicization and intervention.

CONCLUSIONS

A combined clinic and home-based therapeutic approach can be effective for children with HOS to improve alignment and function pre and postpollicization to further enhance hand function. Comprehensive, long-term assessment is necessary to fully evaluate and communicate improvement.

Genetic Basis of Human Congenital Heart Disease

Congenital heart disease (CHD) is the most common major congenital anomaly with an incidence of ∼1% of live births and is a significant cause of birth defect-related mortality. The genetic mechanisms underlying the development of CHD are complex and remain incompletely understood. Known genetic causes include all classes of genetic variation including chromosomal aneuploidies, copy number variants, and rare and common single-nucleotide variants, which can be either de novo or inherited. Among patients with CHD, ∼8%-12% have a chromosomal abnormality or aneuploidy, between 3% and 25% have a copy number variation, and 3%-5% have a single-gene defect in an established CHD gene with higher likelihood of identifying a genetic cause in patients with nonisolated CHD. These genetic variants disrupt or alter genes that play an important role in normal cardiac development and in some cases have pleiotropic effects on other organs. This work reviews some of the most common genetic causes of CHD as well as what is currently known about the underlying mechanisms.

A catalogue of new incidence estimates of monogenic neurodevelopmental disorders caused by de novo variants

A large fraction of rare and severe neurodevelopmental disorders are caused by sporadic de novo variants. Epidemiological disease estimates are not available for the vast majority of these de novo monogenic neurodevelopmental disorders because of phenotypic heterogeneity and the absence of large-scale genomic screens. Yet, knowledge of disease incidence is important for clinicians and researchers to guide health policy planning. Here, we adjusted a statistical method based on genetic data to predict, for the first time, the incidences of 101 known de novo variant-associated neurodevelopmental disorders as well as 3106 putative monogenic disorders. Two corroboration analyses supported the validity of the calculated estimates. First, greater predicted gene-disorder incidences positively correlated with larger numbers of pathogenic variants collected from patient variant databases (Kendall’s τ = 0.093, P-value = 6.9 × 10⁻⁶). Second, for six of seven (86%) de novo variant associated monogenic disorders for which epidemiological estimates were available (SCN1A, SLC2A1, SALL1, TBX5, KCNQ2, and CDKL5), the predicted incidence estimates matched the reported estimates. We conclude that in the absence of epidemiological data, our catalogue of 3207 incidence estimates for disorders caused by de novo variants can guide patient advocacy groups, clinicians, researchers, and policymakers in strategic decision-making.

Familial dilated cardiomyopathy associated with pathogenic TBX5 variants: Expanding the cardiac phenotype associated with Holt-Oram syndrome

Holt-Oram syndrome (HOS) is a rare, autosomal dominant disorder caused by heterozygous pathogenic variants in cardiac T-box transcription factor, TBX5. Classically, it is associated with upper limb malformations and variable cardiac abnormalities. Limb manifestations are considered to be invariably present, ranging in severity from limitation in movement, to triphalangeal thumbs, absent thumbs, shortened forearms, or phocomelia. Cardiac involvement is characterized by congenital heart defects, most commonly septal structural malformations, and conduction system disease. Recently, novel TBX5 variants have also been reported in association with dilated cardiomyopathy (DCM). In this context, we report eight individuals from four unrelated families, in whom pathogenic variants in TBX5 segregated with an atypical HOS phenotype. Affected individuals exhibit relatively mild skeletal features of HOS, with a predominant cardiac phenotype, which includes several individuals affected by non-ischaemic DCM. To our knowledge, these represent the first reported cases of DCM in families with skeletal features of HOS, some of whom also harbored variants previously linked to a classical HOS phenotype (p. Arg279* and p.Arg237Gln). This finding supports diverse roles of TBX5 in cardiovascular development and function, and confirms the importance of long-term cardiac surveillance for individuals affected by HOS. Furthermore, these families highlight the wide phenotypic variability of HOS, which may include comparatively mild upper limb findings in respect to cardiac manifestations.

Growing up with a rare genetic disease: an interpretative phenomenological analysis of living with Holt-Oram syndrome

BACKGROUND

Holt-Oram syndrome (HOS) is a rare genetic disease characterized by variable radial upper limb and cardiac defects. The aim of this research was to shed light on people's subjective perceptions of their diseases, how these perceptions provide meaning, and the consequences the syndrome can have in daily life and across all life stages.

METHODS

Semistructured interviews with ten participants diagnosed with HOS were conducted in France and analyzed using interpretative phenomenological analysis.

RESULTS

Participants' experiences fall under two main themes, namely, "stages of self-construction as different" and "when I am no longer the only one involved", each of which has three subthemes. From childhood onwards, symptoms monopolize the physical and psychological spheres. The feeling of being different is unavoidable until the patient can appropriate his or her condition, and by the end of adolescence, the patient generally feels that he or she has adapted to the syndrome. In adulthood, other concerns arise, such as the fear of rejection, the need to better understand the genetic issues of the condition and the desire for offspring to not experience the same life difficulties.

CONCLUSION

The findings underscore the specific psychological issues associated with the syndrome at different life stages and the need for holistic genetic treatment with dedicated reference centers to improve care and further address these issues.IMPLICATIONS FOR REHABILITATIONHolt-Oram syndrome is a genetic disease characterized by abnormalities of the upper limbs and shoulder girdle and associated with a congenital heart defect.Specific issues arise at different stages of life: the physical consequences of the syndrome arise during childhood, the self-construction of pervasive difference during adolescence, the fear of being rejected as a young adult, and concerns about future parenthood and the transmission of the syndrome and the desire that one's child not be confronted with the same difficulties in adulthood.The complexity and entanglement of medical and existential issues related to HOS requires the development of multidisciplinary consultations that promote holistic care.The rarity of the syndrome and the lack of knowledge about HOS among health professionals and the general public make it necessary both to establish reference centers and to create patient associations to support patients.

Genetic Basis for Congenital Heart Disease: Revisited: A Scientific Statement From the American Heart Association

This review provides an updated summary of the state of our knowledge of the genetic contributions to the pathogenesis of congenital heart disease. Since 2007, when the initial American Heart Association scientific statement on the genetic basis of congenital heart disease was published, new genomic techniques have become widely available that have dramatically changed our understanding of the causes of congenital heart disease and, clinically, have allowed more accurate definition of the pathogeneses of congenital heart disease in patients of all ages and even prenatally. Information is presented on new molecular testing techniques and their application to congenital heart disease, both isolated and associated with other congenital anomalies or syndromes. Recent advances in the understanding of copy number variants, syndromes, RASopathies, and heterotaxy/ciliopathies are provided. Insights into new research with congenital heart disease models, including genetically manipulated animals such as mice, chicks, and zebrafish, as well as human induced pluripotent stem cell-based approaches are provided to allow an understanding of how future research breakthroughs for congenital heart disease are likely to happen. It is anticipated that this review will provide a large range of health care-related personnel, including pediatric cardiologists, pediatricians, adult cardiologists, thoracic surgeons, obstetricians, geneticists, genetic counselors, and other related clinicians, timely information on the genetic aspects of congenital heart disease. The objective is to provide a comprehensive basis for interdisciplinary care for those with congenital heart disease.

Fetal cardiac abnormalities: Genetic etiologies to be considered

Congenital heart diseases are a common prenatal finding. The prenatal identification of an associated genetic syndrome or a major extracardiac anomaly helps to understand the etiopathogenic diagnosis. Besides, it also assesses the prognosis, management, and familial recurrence risk while strongly influences parental decision to choose termination of pregnancy or postnatal care. This review article describes the most common genetic diagnoses associated with a prenatal finding of a congenital heart disease and a suggested diagnostic process.

Holt-Oram syndrome: clinical and molecular description of 78 patients with TBX5 variants

Holt-Oram syndrome (HOS) is an autosomal dominant condition characterised by the association of congenital heart defect (CHD), with or without rhythm disturbances and radial defects, due to TBX5 variants. The diagnosis is challenged by the variability of expression and the large phenotypic overlap with other conditions, like Okihiro syndrome, TAR syndrome or Fanconi disease. We retrospectively reviewed 212 patients referred for suspicion of HOS between 2002 and 2014, who underwent TBX5 screening. A TBX5 variant has been identified in 78 patients, representing the largest molecular series ever described. In the cohort, 61 met the previously described diagnostic criteria and 17 have been considered with an uncertain HOS diagnosis. A CHD was present in 91% of the patients with a TBX5 variant, atrial septal defects being the most common (61.5%). The genotype-phenotype study highlights the importance of some critical features in HOS: the septal characteristic of the CHD, the bilateral and asymmetric characteristics of the radial defect and the presence of shoulder or elbow mobility defect. Besides, 21 patients presented with an overlapping condition. Among them, 13 had a typical HOS presentation. We discuss the strategies that could be adopted to improve the molecular delineation of the remaining typical patients.

A novel de novo TBX5 mutation in a patient with Holt-Oram syndrome

Holt-Oram syndrome (HOS) is an autosomal dominant disorder characterized by congenital cardiac defects and congenital deformities of the upper limbs. Herein, we report the case of a 2-year-old patient presenting with clinical diagnostic criteria of HOS with interatrial and interventricular communication associated with hip dysplasia and upper limb reduction composed of radial ray anomaly. A novel de novo, potentially pathogenic variant in the TBX5 gene at NM_181486.2:c.243-1G>C was identified.

Holt-Oram Syndrome With Multiple Cardiac Abnormalities

Holt-Oram syndrome (HOS) is a rare monogenic disorder characterized by upper limb abnormalities, congenital heart defects and/or conduction abnormalities. It is determined by mutations of TBX5 gene and is inherited in an autosomal dominant manner. Penetrance is complete, but variable expressivity is present, which gives sometimes diagnostic difficulties. Our case is a young adult with a personal history of preaxial polydactyly operated in infancy, multiple cardiac malformations (atrial septal defect, bicuspid aortic valve, left ventricular non-compaction) and radiologic findings consistent with HOS. Family history is negative for HOS. In conclusion, we present a case of HOS diagnosed in the adult period to highlight the diagnostic problems for the proband and the family and the importance of an early diagnostic.

The Occurrence of 275 Rare Diseases and 47 Rare Disease Groups in Italy. Results from the National Registry of Rare Diseases

Knowledge of rare diseases (RD) is often scattered among many data collections and registries of patient cohorts. Therefore, assessing the burden of RD in the general population, developing appropriate policies and planning services for the care of RD patients is difficult. This study aimed at providing a systematic picture of RD occurrence in a population as big as 60 million. Data of diagnoses were certified and collected by a network of 247 specialized centres covering the whole Italian territory. Data received (about 200,000 records) were validated according to formal criteria and, where necessary, corrected by the data sources. Data of age at onset and sex distribution are given for about 400 diseases. Incidence and/or birth prevalence are given for 275 diseases and 47 disease groups, which, altogether, comprise a substantial part of the known rare diseases. Data quality, internal consistency, and external validity of the database have also been assessed and ways to limit the impact of some discrepancies were devised. The information provided by RNMR, cutting across such a wide range of RD, represents a unique coherent basis allowing the prioritization of relevant public health measures and research activities.

Clinical and epidemiological features of Heart-Hand Syndrome: a hospital-based study in China

Heart–hand syndrome (HHS) is a clinically and genetically heterogeneous disorder characterized by the co-occurrence of a congenital cardiac disease and an upper limb malformation. This study revealed the clinical and epidemiological features of HHS in China. The study was based on patients with congenital upper limb malformation treated in Beijing Ji Shui Tan hospital from October 1^st, 2013 to October 1^st, 2016. We reviewed the patients’ medical records and identified patients with abnormal ultrasonic cardiogram and/or electrocardiogram (ECG). A total of 1462 patients (910 male and 552 female) were identified to be treated for congenital upper limb malformation. Among them, 172 (11.8%) had abnormal ultrasonic cardiogram and/or ECG. Abnormal heart structure were discovered in 121 patients and 51 patients had abnormal ECG. The most common type of abnormal heart structure was tricuspid regurgitation (53/121, 43.8%), while the most common abnormal ECG was wave patterns (22/51, 43.1%). This hospital-based study suggests that the rate of congenital heart disease is high in patients treated for congenital upper extremity malformation in China. Surgeons and anesthetists should be aware of the comorbidity and preoperational examination of congenital heart diseases is highly needed to avoid complications during operation.

EUROCAT: an update on its functions and activities

This paper provides an outline of the development and growth of EUROCAT, the European network of congenital anomaly registers. In recent years the network has been through a period of transition and change. The Central Register of data has transferred from the Ulster University to the EU Joint-Research-Centre, Ispra, Italy.The benefits of combining data from across Europe, from different populations and countries are described by the uses to which these data can be put. These uses include:. surveillance of anomalies at a local, regional or pan-European level. pharmacovigilance. registration of rare diseasesNew studies and projects are underway, including EUROlinkCAT (a Horizon 2020 funded data-linkage project), promising a fruitful future in further research of congenital anomalies.

Coexisting urogenital anomaly and duodenal atresia in two atypical Holt-Oram syndrome

Holt-Oram syndrome (HOS) is a rare autosomal dominant disorder, characterized by upper limb dysplasia and congenital cardiac defect. We report two cases with HOS, first associated with renal agenesis, coronal hypospadias, urethral duplication and second associated with duodenal atresia and horseshoe kidney that have not been reported in English literature.

TBX5: A Key Regulator of Heart Development

TBX5 is a member of the T-box transcription factor family and is primarily known for its role in cardiac and forelimb development. Human patients with dominant mutations in TBX5 are characterized by Holt-Oram syndrome, and show defects of the cardiac septa, cardiac conduction system, and the anterior forelimb. The range of cardiac defects associated with TBX5 mutations in humans suggests multiple roles for the transcription factor in cardiac development and function. Animal models demonstrate similar defects and have provided a useful platform for investigating the roles of TBX5 during embryonic development. During early cardiac development, TBX5 appears to act primarily as a transcriptional activator of genes associated with cardiomyocyte maturation and upstream of morphological signals for septation. During later cardiac development, TBX5 is required for patterning of the cardiac conduction system and maintenance of mature cardiomyocyte function. A comprehensive understanding of the integral roles of TBX5 throughout cardiac development and adult life will be critical for understanding human cardiac morphology and function.

Embryonic hypocellularity, blastogenetic malformations, and fetal growth restriction

An association between congenital malformations and fetal growth restriction (FGR) can be largely explained by a relationship with early embryonic hypocellularity. The malformations include the VACTERL association, which is exceptional as a Mendelian syndrome, but is commonly associated with monozygotic twinning, maternal diabetes, and some forms of aneuploidy, all characterized by a small embryo early in development. Parsimony suggests that these different links to VACTERL are related to the hypocellularity as a single common factor, rather than as an expression of three independent pathogenetic processes. A distinct non-genetic pathogenesis is further supported by increased frequencies in the same conditions of a single umbilical artery (SUA), which is also unusual in Mendelian disorders. SUA often involves the atrophy of one artery, which may be facilitated by altered hemodynamics in a smaller embryo, providing a direct link to hypocellularity. Hypocellularity may also explain a possible connection between VACTERL and certain mitochondrial disorders, where reduced energy might slow early cell division and growth, reducing the size of the embryo. © 2016 Wiley Periodicals, Inc.

Syndromic anorectal malformation associated with Holt-Oram syndrome, microcephaly, and bilateral corneal opacity: a case report

BACKGROUND

The occurrence of an anorectal malformation with Holt-Oram syndrome, microcephaly, and bilateral corneal opacity is rare and to the best of our knowledge has not previously been reported in the literature. Hence, there is a need to document our experience in this case and learn as much as possible from it.

CASE PRESENTATION

We present the case of a Nigerian female neonate with a postnatal diagnosis of syndromic anorectal malformation associated with Holt-Oram syndrome, microcephaly, and bilateral corneal opacity. The infant had successful staged correction of her anorectal malformation but developed a metastatic Wilms' tumor and died before other corrective procedures could be instituted.

CONCLUSIONS

An anorectal malformation is here reported to occur with Holt-Oram syndrome, an association that has not been reported previously. To enhance the prognosis and quality of life of children with syndromic anorectal malformation, prenatal ultrasound monitoring of high-risk pregnancies and expertise in prenatal detection of congenital anomalies are invaluable in antenatal care.

Role of Genetic Factors in the Pathogenesis of Radial Deficiencies in Humans

Radial deficiencies (RDs), defined as under/abnormal development or absence of any of the structures of the forearm, radial carpal bones and thumb, occur with a live birth incidence ranging from 1 out of 30,000 to 1 out 6,000 newborns and represent about one third/one fourth of all the congenital upper limb anomalies. About half of radial disorders have a mendelian cause and pattern of inheritance, whereas the remaining half appears sporadic with no known gene involved. In sporadic forms certain anomalies, such as thumb or radial hypoplasia, may occur either alone or in association with systemic conditions, like vertebral abnormalities or renal defects. All the cases with a mendelian inheritance are syndromic forms, which include cardiac defects (in Holt-Oram syndrome), bone marrow failure (in Fanconi anemia), platelet deficiency (in thrombocytopenia-absent-radius syndrome), ocular motility impairment (in Okihiro syndrome). The genetics of radial deficiencies is complex, characterized by genetic heterogeneity and high inter- and intra-familial clinical variability: this review will analyze the etiopathogenesis and the genotype/phenotype correlations of the main radial deficiency disorders in humans.

Absent Left Main Coronary Artery and Separate Ostia of Left Coronary System in a Patient with Holt-Oram Syndrome and Sinus Node Dysfunction

Patient: Male, 41

Final Diagnosis: Sick Sinus Syndrome and absent left main coronary artery • separate ostia of left anterior descending and circumflex arteries in Holt-Oram Syndrome

Symptoms: Conduction disturbance • seizure-like activity • upper extremity malformations

Medication: —

Clinical Procedure: Electro physiology study • coronary catheterization • pacemaker

Specialty: Cardiology

Defining Features of the Upper Extremity in Holt-Oram Syndrome

PURPOSE

To investigate the distinguishing morphological characteristics of children with radial longitudinal deficiency (RLD) in Holt-Oram syndrome (HOS).

METHODS

One hundred fourteen involved extremities in 62 patients with a diagnosis of HOS were identified at 3 institutions. Medical records and radiographs were evaluated. Radial longitudinal deficiency and thumb hypoplasia were classified according to the modified Bayne and Klug classification and Blauth classifications, respectively, when possible. Other unusual or distinguishing characteristics were catalogued.

RESULTS

There was bilateral involvement in 84% of patients. The forearm was involved in 81% of the extremities and a shortened distal radius (Bayne and Klug type I RLD) was the most commonly identified forearm anomaly (40%). Radioulnar synostosis was present in 15% of the extremities, all in the proximal forearms with reduced radial heads. Thumb aplasia (Blauth type V hypoplastic thumb) was the most common type of classifiable thumb abnormality and occurred in 35% of involved thumbs. Twenty-seven percent of abnormal thumbs affected were not classifiable according to the Blauth classification, and 19% of involved thumbs (hypoplastic or absent) had first-web syndactyly.

CONCLUSIONS

The upper extremity in HOS differs from the typical presentation of RLD. The forearm is more often involved and may demonstrate radioulnar synostosis. The thumb is frequently unclassifiable by the Blauth classification and has first-web syndactyly. The presence of radioulnar synostosis and syndactyly of the radial 2 digits in RLD should prompt the hand surgeon to obtain a cardiac evaluation and consider genetic testing for HOS.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic III.