Defects In Upper Limb Research Articles

Abstract 44: Interaction Of Osr1 And Tbx5 Is Involved In The Mouse Limb And Heart Development

Mutations of TBX5 cause Holt-Oram syndrome (HOS) in human, a disease characterized by upper limb and heart defects. Mouse embryos of Osr1 knockout caused similar heart defects, while the upper limb defects have never been reported. By genetically marking Osr1 expressing cells in mice, using Osr1:CreERT2 , we showed that Osr1 expression cells contribute to the atrial septum progenitors between E8.0 and E11.0, and to the forelimb after E9.0. The expression of Osr1 in the forelimb showed a gradient decreasing pattern from the digit 5 to digit 1. Conditional- Tbx5 haploinsuffiency, using Osr1:CreERT2 , compound with Osr1 haploinsuffiency induced more incidence of atrial septal defects (ASDs) and double outlet right ventricle (DORV). Forty percent of these embryos also had digit defects: the digits are either missing, fused or lack normal identity, which were not observed in mouse embryos of either Osr1 or Tbx5 haploinsuffiency. Detailed study of the cardiac progenitors of the compound haploinsufficinecy for Tbx5 and Osr1 showed decreased proliferation in the posterior second heart field, which was associated with lower number of cells transiting from G2 to M phase and less gene expression of Cdk6 and CyclinD2 . In summary, our study demonstrated that interaction of Osr1 and Tbx5 is involved in the mouse limb and heart development and provides a potential mechanism for HOS.

Holt–Oram syndrome with intermediate atrioventricular canal defect, and aortic coarctation: Functional characterization of a de novo TBX5 mutation

Holt-Oram syndrome (HOS) is a rare autosomal dominant disorder characterized by upper limb defects and congenital heart defects (CHD), which are often simple septal and conduction defects, less frequently complex CHDs. We report on a 9 year-old boy with clinical and radiologic features of HOS consisting of bilateral asymmetric hypoplastic thumbs, generalized brachydactyly, limited supination due to radioulnar synostosis, and sloping shoulders, and intermediate atrioventricular canal defect (AVCD) with aortic coarctation. A de novo, previously described mutation, (Arg279ter) was identified in the TBX5 gene. Molecular characterization of this mutation was carried out due to the atypical CHD. In order to investigate whether the mutated transcript of TBX5 was able to escape the post-transcriptional surveillance mechanism and to produce a truncated TBX5 protein, we analyzed the TBX5 transcript, and protein pattern in HOS, and WT cardiac tissues. Our results demonstrate that the mutant TBX5 transcript is cleared by the cellular mechanism of surveillance. This data provides some support for the hypothesis that a dominant negative mutation, which strongly impairs the WT allele, might be too hazardous to be maintained. The literature suggests that HOS is relatively common among syndromes associated with AVCD.

Index of Suspicion

The reader is encouraged to write possible diagnoses for each case before turning to the discussion. We invite readers to contribute case presentations and discussions. Please inquire first by contacting Dr. Deepak Kamat at DKamat@med.wayne.edu. An 18-year-old male with a 3-year history of alcohol abuse is referred from a rehabilitation center for fever, nausea, and nonbloody diarrhea for 3 days. Six weeks ago, he enrolled in an alcohol rehabilitation program and stopped drinking alcohol. Three weeks later, he noticed yellowing of his eyes and skin, difficulty sleeping, and dyspnea. On examination, his temperature is 100.6°F (38.1°C), blood pressure is 99/62 mm Hg, pulse is 124 beats per minute, and respiratory rate is 24 breaths per minute. He is slow to answer questions. There is no asterixis. He appears thin and jaundiced with enlarged parotid glands. Decreased breath sounds are noted on the right. A tender, enlarged liver and mild abdominal distension are noted. Trace bilateral lower-extremity edema is present. No stigmata of chronic liver disease are found. Laboratory findings reveal the following: white blood cell count, 25,600/μL (25.6 × 109/L) (87% neutrophils); hemoglobin, 8.2 g/dL (82 g/L); mean corpuscular volume, 106 fL; platelets, 40 × 103/μL (40 × 109/L); sodium, 135 mEq/L (135 mmol/L); potassium, 3.5 mEq/L (3.5 mmol/L); chloride, 106 mEq/L (106 mmol/L); bicarbonate, 15 mEq/L (15 mmol/L); blood urea nitrogen, 24 mg/dL (8.6 mmol/L); creatinine, 1.01 mg/dL (89 μmol/L); glucose, 118 mg/dL (6.6 mmol/L); alkaline phosphatase, 182 U/L; aspartate aminotransferase (AST), 194 U/L; alanine aminotransferase (ALT), 71 U/L; total bilirubin, 11.8 mg/dL (201.8 μmol/L); direct bilirubin, 7.3 mg/dL (124.9 μmol/L); albumin, 2.7 g/dL (27 g/L); prothrombin time, 19.2 seconds; and international normalized ratio, 1.4. Ethanol and acetaminophen were not detected in the serum. A chest radiograph reveals a right pleural effusion …

Molecular confirmation of nine cases of Cornelia de Lange syndrome diagnosed prenatally

Cornelia de Lange syndrome (CdLS) is characterized by distinct facial features, growth retardation, upper limb reduction defects, hirsutism, and intellectual disability. NIPBL mutations have been identified in approximately 60% of patients with CdLS diagnosed postnatally. Prenatal ultrasound findings include upper limb reduction defects, intrauterine growth restriction, and micrognathia. CdLS has also been associated with decreased PAPP-A and increased nuchal translucency (NT). We reviewed NIPBL sequence analysis results for 12 prenatal samples in our laboratory to determine the frequency of mutations in our cohort. This retrospective study analyzed data from all 12 prenatal cases with suspected CdLS, which were received by The University of Chicago Genetic Services Laboratories. Diagnostic NIPBL sequencing was performed for all samples. Clinical information was collected from referring physicians. NIPBL mutations were identified in 9 out of the 12 cases prenatally (75%). Amongst the NIPBL mutation-positive cases with clinical information available, the most common findings were upper limb malformations and micrognathia. Five patients had NT measurements in the first trimester, of which four were noted to be increased. We demonstrate that prenatally-detected phenotypes of CdLS, particularly severe micrognathia and bilateral upper limb defects, are associated with an increased frequency of NIPBL mutations.

Ectopic Limb in the Left Side of the Thorax

We report a case of ectopic left upper limb located in the left side of the thorax in a 3-day neonate. The patient had dyspnea and deficiency of the left upper limb. Multidetector computed tomography (Fig 1A,B, arrow) revealed an “armlike” structure occupying most of the left side of the thoracic cavity; it included the humerus, ulna, radius, and palm. The bony structure was folded, with a mixed-intensity mass around it, consisting of muscle and fat (Fig 1C, arrow). It was firmly adherent to the left border of the mediastinum, leading to left pulmonary atelectasis and displacement of the heart. The lesion was removed by a radical surgical procedure. Congenital upper limb defects are extremely rare, with an incidence of 0.4%, and may be accompanied by other anomalies or syndromes [1] .A n absent limb located in the thorax has been especially rare; we have not been able to trace other similar records in the literature. In our case, the images offered detailed information to enable the patient to be scheduled for operation.

Characteristics and associated anomalies in radial ray deficiencies in Finland—A population‐based study

Upper-limb defects with deficiencies of the radial ray have varying etiologies, with a low proportion of true Mendelian disorders. We carried out a population-based study to elucidate the birth prevalence and clinical spectrum of radial ray deficiencies in Finland. We identified all births with radial ray deficiency reported to the Finnish Register of Congenital Malformations in 1993-2005. Altogether 138 cases were identified (123 live births), with a birth prevalence of 1.83 per 10,000 births and a live birth prevalence of 1.64 per 10,000 live births. The proportion of infant deaths was as high as 35%. The majority of the cases were associated with known syndromes or multiple anomalies; only 13% were true isolated radial ray deficiencies. The most common syndrome was trisomy 18, and the most common in multiple anomalies was VACTERL association. In 8.7% of cases an association between radial ray deficiency and heart anomaly was observed. The high proportion of cases with associated major anomalies indicates that radial ray deficiency can be regarded isolated only after thorough assessment of the various organ systems in an affected infant.

Sirenomelia: Case Reports and Current Concepts of Pathogenesis

We present 2 cases of sirenomelia and highlight the recent theories about its pathogenesis. Both cases had a large aberrant abdominal umbilical artery (AAUA) arising from the aorta, suggesting vascular steal as the pathophysiology. However, the bilateral upper limb defects noted in 1 case, the reported 10% association of holoprosencephaly and anencephaly, and the reports of sirenomelia with normal umbilical arteries point to the alternative caudal dysgenesis (CD) theory. This proposes that an insult at the early blastogenic stage interferes with the formation of the notochord, resulting in abnormal development of caudal structures, an AAUA, and occasional neural tube defects. We have also analyzed the implications of the similarities between sirenomelia/CD and the VATER association; the increased risk of CD but not sirenomelia in infants of diabetic mothers; the fact that sirenomelia, holoprosencephaly, and the VATER association are all more common in monozygotic twins; the experimental production of sirenomelia in mice; and the possible genetic implications of the co-occurrence of sirenomelia and CD.

Sirenomelia

Sirenomelia, also known as the 'mermaid malformation/syndrome', is a rare, serious congenital anomaly characterized by variable degrees of fusion of the lower limbs and associated severe malformations of the lower vertebral and genitourinary systems. In this report, we describe a series of African patients with sirenomelia. We present the clinical and radiological features of four black South African patients and illustrate some of the rarer associated abnormalities, which include asymmetrical upper limb defects, not confined to the radial ray. The clinical phenotypic overlap between caudal dysgenesis, VACTERL association and sirenomelia in our patients is highlighted, lending support to the theory that these entities may be different manifestations of a single pathogenic process.

Reconstruction of extensive upper extremity defects using pre-expanded oblique perforator-based paraumbilical flaps

The pedicled paraumbilical flap is a reliable tissue transfer for hand and forearm reconstruction. However, its size, pedicle length and/or thickness limit its application in resurfacing of extensive defects of the upper limb. To conquer those limitations, this flap was pre-expanded for 10–24 weeks prior to transfer in 25 patients and used as a pedicle flap to cover upper extremity defects. Extensive defects of upper limb were reconstructed by the pre-expanded paraumbilical flaps. The flaps ranged in size from 10cm×8cm to 30cm×14cm. The donor sites were closed directly in all cases. All flaps survived, but two had partial flap necrosis due to venous congestion or infection. With pre-transfer expansion, a large, well-perfused abdominal pedicle flap can be raised and transferred based on the paraumbilical perforators. This pre-expanded flap might be useful in the patients who have the extensive upper limb defects and sufficient time to allow tissue expansion.

TBX5 intragenic duplication: a family with an atypical Holt–Oram syndrome phenotype

Holt-Oram syndrome (HOS) is a rare autosomal dominant heart-hand syndrome due to mutations in the TBX5 transcription factor. Affected individuals can have structural cardiac defects and/or conduction abnormalities, and exclusively upper limb defects (typically bilateral, asymmetrical radial ray defects). TBX5 mutations reported include nonsense, missense, splicing mutations and exon deletions. Most result in a null allele and haploinsufficiency, but some impair nuclear localisation of TBX5 protein or disrupt its interaction with co-factors and downstream targets. We present a five generation family of nine affected individuals with an atypical HOS phenotype, consisting of ulnar ray defects (ulnar hypoplasia, short fifth fingers with clinodactyly) and very mild radial ray defects (short thumbs, bowing of the radius and dislocation of the radial head). The cardiac defects seen are those more rarely reported in HOS (atrioventricular septal defect, hypoplastic left heart syndrome, mitral valve disease and pulmonary stenosis). Conduction abnormalities include atrial fibrillation, atrial flutter and sick sinus syndrome. TBX5 mutation screening (exons 3-10) identified no mutations. Array comparative genomic hybridisation (CGH) revealed a 48 kb duplication at 12q24.21, encompassing exons 2-9 of the TBX5 gene, with breakpoints within introns 1-2 and 9-10. The duplication segregates with the phenotype in the family, and is likely to be pathogenic. This is the first known report of an intragenic duplication of TBX5 and its clinical effects; an atypical HOS phenotype. Further functional studies are needed to establish the effects of the duplication and pathogenic mechanism. All typical/atypical HOS cases should be screened for TBX5 exon duplications.

Dorsal Decubitus Positioning

The latissimus dorsi, whether taken as a muscle or with a skin paddle, is one of the most useful flaps in the reconstructive surgeon's arsenal. With its predictable type V vascular pedicle, this broad muscle can be elevated on its dominant thoracodorsal pedicle or used in a reverse manner on its secondary thoracic and lumbar perforators. Traditionally harvested in a lateral decubitus position, over the last 10 years we have chosen to elevate this muscle in a dorsal decubitus position, enabling 2 surgical teams to operate simultaneously. With only one cushion placed along the vertebral column between the scapulas, each element of the subscapular system, including scapular bone, can be used to reconstruct complex upper limb defects. A vertical incision in front of the anterior axillary line is performed to identify the anterior border of the muscle, followed by a dissection in the submuscular plane to reveal the thoracodorsal pedicle and its branches. When a more complex chimeric flap is required, scapular bone, serratus muscle, and scapular or parascapular fasciocutaneous flaps are all available. To achieve the longest length possible, the pedicle can be isolated from the axillary vessels. The most common complications are related to donor site, with seroma and delayed wound healing being the most prevalent. Complaints of shoulder pain and functional disability were rare and mostly encountered in the first 2 weeks postoperatively.

Congenital Upper Limb Deficiencies and Associated Malformations in Finland: A Population-Based Study

To calculate the national incidence of upper limb deficiencies and associated infant mortality in children in Finland using the International Federation of Societies for Surgery of the Hand (IFSSH) classification. Radial ray deficiency, ulnar ray deficiency, central ray deficiency, transverse arrest, phocomelia, undergrowth, and constriction band syndrome with skeletal defects were evaluated. We reviewed upper limb deficiencies among all 753,342 births in Finland during 1993 to 2005 reported to the Finnish Register of Congenital Malformations. Classification of these upper limb deficiencies was done according to a modified IFSSH system. We calculated incidence, gender and side distributions, frequency of associated anomalies, and infant mortality rates in different subtypes of the deficiencies. Familial occurrence of congenital upper limb defects was recorded. A total of 419 cases (234 male, 185 female) of upper limb deficiencies were identified. The national incidence of upper limb deficiencies was 5.56 per 10,000 births and 5.25 per 10,000 live births. The most common upper limb abnormality was radial ray deficiency (138), followed by subgroups of undergrowth (91), upper limb defects due to constriction band syndrome (51), central ray deficiency (41), and ulnar ray deficiency (33). Perinatal mortality was 14%. Infant mortality among children with upper limb deficiencies was 137 per 1,000 live births, compared with an overall infant mortality of 3.7 per 1,000 live births in Finland. Additional birth defects were found in 60% of these children. Prevalence of upper limb defects in relatives of the census population was 2% (11 of 419). The national incidence of upper limb deficiencies is 5.25 per 10,000 live births. Congenital upper limb deficiencies are associated with additional birth defects in two thirds of cases. These children, especially children with radial ray deficiency, have a high perinatal mortality rate. When divided into subgroups using IFSSH classification, differences emerge in both associated anomalies and mortality.

Induction of apoptosis and inhibition of cell growth by tbx5 knockdown contribute to dysmorphogenesis in Zebrafish embryos

BackgroundThe tbx5 mutation in human causes Holt-Oram syndrome, an autosomal dominant condition characterized by a familial history of congenital heart defects and preaxial radial upper-limb defects. We report aberrant apoptosis and dormant cell growth over head, heart, trunk, fin, and tail of zebrafish embryos with tbx5 deficiency correspond to the dysmorphogenesis of tbx5 morphants.MethodsWild-type zebrafish embryos at the 1-cell stage were injected with 4.3 nl of 19.4 ng of tbx5 morpholino or mismatch-tbx5-MO respectively in tbx5 morphants and mismatched control group. Semi-quantitative RT-PCR was used to for expression analysis of apoptosis and cell cycle-related genes. TUNEL and immunohistochemical assay showed the apoptosis spots within the local tissues. Ultra-structure of cardiac myocardium was examined by transmission electron microscope.ResultsApoptosis-related genes (bad, bax, and bcl2), and cell cycle-related genes (cdk2, pcna, p27, and p57) showed remarkable increases in transcriptional level by RT-PCR. Using a TUNEL and immnuohistochemical assay, apoptosis was observed in the organs including the head, heart, pectoral fins, trunk, and tail of tbx5 knockdown embryos. Under transmission electron microscopic examination, mitochondria in cardiomyocytes became swollen and the myocardium was largely disorganized with a disarrayed appearance, compatible with reduced enhancement of myosin in the cardiac wall. The ATP level was reduced, and the ADP/ATP ratio as an apoptotic index significantly increased in the tbx5 deficient embryos.ConclusionOur study highlighted that tbx5 deficiency evoked apoptosis, distributed on multiple organs corresponding to dysmorphogenesis with the shortage of promising maturation, in tbx5 knockdown zebrafish embryos. We hypothesized that mesenchymal cell apoptosis associated with altered TBX5 level may subsequently interfered with organogenesis and contributed to dysmorphogenesis in tbx5 deficiency zebrafish embryos.

Cornelia de Lange syndrome, cohesin, and beyond

Cornelia de Lange syndrome (CdLS) (OMIM #122470, #300590 and #610759) is a dominant genetic disorder with multiple organ system abnormalities which is classically characterized by typical facial features, growth and mental retardation, upper limb defects, hirsutism, gastrointestinal and other visceral system involvement. Mutations in three cohesin proteins, a key regulator of cohesin, NIPBL, and two structural components of the cohesin ring SMC1A and SMC3, etiologically account for about 65% of individuals with CdLS. Cohesin controls faithful chromosome segregation during the mitotic and meiotic cell cycles. Multiple proteins in the cohesin pathway are also involved in additional fundamental biological events such as double-strand DNA break repair and long-range regulation of transcription. Moreover, chromosome instability was recently associated with defective sister chromatid cohesion in several cancer studies, and an increasing number of human developmental disorders is being reported to result from disruption of this pathway. Here, we will discuss the human disorders caused by alterations of cohesin function (termed 'cohesinopathies'), with an emphasis on the clinical manifestations of CdLS and mechanistic studies of the CdLS-related proteins.

Congenital Thumb Deformities and Associated Syndromes

Upper limb defects occur in approximately 3.4 per 10,000 live births. Major thumb defects represent 16% of these upper limb defects (Tay SC, Moran SL, Shin AY, et al. The hypoplastic thumb. J Am Acad Orthop Surg 2006;14:354-366). Embryologically, hand development begins by the fifth week. This occurs simultaneously with the growth and development of the cardiovascular, neurologic, and hematopoietic systems. Therefore, congenital anomalies seen in the hands of infants may indicate significant anomalies in these other systems, requiring a comprehensive physical evaluation. Although the cause of 40% to 50% of congenital hand anomalies is unknown (Gallant GG, Bora FW. Congenital deformities of the upper extremity. J Am Acad Orthop Surg 1996;4:163-171), several others have traced this to specific genetic mutations. Others are due to a variety of teratogenic effects (Sadler TW. Langman's Medical Embryology. 10th ed. Philadelphia: Lippincott Williams &Wilkins, Chapter 9, 2006:125-142). For the clinician, this paper has been organized to identify possible corresponding syndromes that may accompany specific thumb deformities.

The pedicled thoraco-umbilical flap: A versatile technique for upper limb coverage

ABSTRACTInjuries to upper limb has been on the increase and is invariably associated with significant soft tissue loss requiring a flap cover. Local tissue may not be available for cover in a majority of situations, necessitating import of tissue from a distant source. We have utilized the thoraco-umbilical flap taken from the trunk for this purpose. This flap is based on the perforators of the deep inferior epigastric artery that are maximally centred on the periumbilical region. This flap was used in 83 patients. The patients were observed for at least 3 weeks and any flap or donor site complications were recorded. The patients were again followed up at 3 months interval and the donor site scar was assessed. The flaps survived in 81 patients; there was marginal flap necrosis in five patients and partial flap necrosis in two patients. None of these patients required any additional procedure for coverage. The flap is technically easy to plan, almost effortless to drape around upper limb defects, with no significant donor site morbidity and also the post operative immobilization was fairly comfortable. The thoraco-umbilical flap thus is a very useful technique for coverage of the upper limb and is recommended as a first line flap for this purpose.

Poland syndrome with bilateral features: Case description with review of the literature

Poland syndrome (PS) has been described as unilateral pectoral muscle deficiency variably associated with ipsilateral thoracic and upper limb anomalies. Bilateral hypoplasia/aplasia of the pectoralis muscle and upper limb defects in association with variable thoracic muscles, chest wall deformities and lower limb defects have been infrequently reported in the literature. We report on a 3(1/2)-year-old girl with clinical features consisting in bilateral asymmetric pectoral muscle defects (complete agenesis on the left side and agenesis of the sternocostal head on the right side), nipple hypoplasia, left rib defect, and right hand symbrachydactyly. In this study, we reviewed the bilateral features present in our patient and those described in the literature. Hypotheses explaining bilateral features in PS are reviewed.

Management of Extensive or Infected Soft Tissue Defects in Upper Limb by Means of Pediculated Omental Flaps

Management of Extensive or Infected Soft Tissue Defects in Upper Limb by Means of Pediculated Omental Flaps

The pedicled thoraco-umbilical flap: A versatile technique for upper limb coverage

Injuries to upper limb has been on the increase and is invariably associated with significant soft tissue loss requiring a flap cover. Local tissue may not be available for cover in a majority of situations, necessitating import of tissue from a distant source. We have utilized the thoraco-umbilical flap taken from the trunk for this purpose. This flap is based on the perforators of the deep inferior epigastric artery that are maximally centred on the periumbilical region. This flap was used in 83 patients. The patients were observed for at least 3 weeks and any flap or donor site complications were recorded. The patients were again followed up at 3 months interval and the donor site scar was assessed. The flaps survived in 81 patients; there was marginal flap necrosis in five patients and partial flap necrosis in two patients. None of these patients required any additional procedure for coverage. The flap is technically easy to plan, almost effortless to drape around upper limb defects, with no significant donor site morbidity and also the post operative immobilization was fairly comfortable. The thoraco-umbilical flap thus is a very useful technique for coverage of the upper limb and is recommended as a first line flap for this purpose.

Diagnostic and counselling dilemmas arising from prenatal sonography with radial ray defects

Primary infertility led to conception by in vitro fertilisation. Anomaly scan revealed upper limb defects. After termination of pregnancy, post mortem found radial ray defects and facial dysmorphism. Fetal chromosomal analysis, parental karyotyping and genetic studies were normal. Difficulty in this case lay with determining a definitive diagnosis which has implications on recurrence and counselling. Nager syndrome is the closest possible diagnosis. This case shows that it is essential for obstetricians to have good communication and counselling skills. A multidisciplinary team approach is important including the fetomaternal specialist, geneticist and pathologist.