Tbx4 function during hindlimb development reveals a mechanism that explains the origins of proximal limb defects.

We dissect genetically a gene regulatory network that involves the transcription factors Tbx4, Pitx1 and Isl1 acting cooperatively to establish the hindlimb bud, and identify key differences in the pathways that initiate formation of the hindlimb and forelimb. Using live image analysis of murine limb mesenchyme cells undergoing chondrogenesis in micromass culture, we distinguish a series of changes in cellular behaviours and cohesiveness that are required for chondrogenic precursors to undergo differentiation. Furthermore, we provide evidence that the proximal hindlimb defects observed in Tbx4 mutant mice result from a failure in the early differentiation step of chondroprogenitors into chondrocytes, providing an explanation for the origins of proximally biased limb defects.

Heavy metals and trace elements in maternal blood and prevalence of congenital limb abnormalities among newborns: the Japan Environment and Children's Study.

BACKGROUND: Heavy metals such as lead (Pb) and cadmium (Cd) have been associated with adverse pregnancy and developmental outcomes, including congenital abnormalities. This study investigated the association between exposure to heavy metals and trace elements during fetal life and congenital limb abnormalities in infants. METHODS: This study is based on a prospective ongoing nationwide birth cohort from the Japan Environment and Children's Study (JECS). The concentrations of Cd, Pb, mercury (Hg), selenium (Se), and manganese (Mn) were measured in maternal blood collected during the mid-late trimesters. Inclusion criteria were available from questionnaires filled in during pregnancy, including information about congenital limb abnormalities at birth or at one month. To examine the associations with limb anomalies and individual chemicals, logistic regression models were applied following log-transformation or division into quartiles of Cd, Pb, Hg, Se, and Mn concentrations. To assess the associations with the heavy metals and trace elements mixture, quantile g-computation was employed. All models were adjusted for age, maternal smoking history, maternal alcohol intake, history of smoking, and infant sex. RESULTS: Data from 90,163 participants were included in the analysis, of whom 369 had congenital limb abnormalities in any of the collected information, and 89,794 had none. Among the 369 cases of congenital limb abnormalities, there were 185 and 142 cases of polydactyly and syndactyly, respectively. The median concentrations of Pb, Cd, Hg, Se, and Mn were 5.85, 0.66, 3.64, 168, and 15.3 ng/g, respectively. There were no associations between maternal blood concentrations of Pb [adjusted odd ratio = 0.83; 95% confidence interval = 0.61, 1.11], Cd [0.87; 0.68, 1.10], Hg [0.88; 0.73, 1.07], Se [1.07; 0.44, 2.59], and Mn [0.91; 0.64, 1.30] with congenital limb abnormalities. No significant association was observed between the mixture of heavy metals and trace elements [0.85; 0.72, 1.02] and any congenital limb abnormalities. Moreover, there was no association with all polydactylies and all syndactylies, or any type of abnormality as a subdivision. CONCLUSION: At the maternal exposure levels of Cd, Pb, Hg, Se, and Mn assessed in the present study, no association was identified with the risk of developing congenital limb abnormalities in children.

46,XY DSD and limb abnormalities in a female with a de novo LHX9 missense mutation.

Differences in sex development (DSD) are a group of rare conditions involving genes, hormones and reproductive organs, including genitals. Although these disorders are common, information about the molecular causes remain limited. Many genes have been identified in association with DSD but in many cases the causative gene could not be identified. The Lhx9 gene has been studied in mice and birds, and biallelic mutations in this gene have been found to cause 46,XY DSD and limb abnormalities. So far two variants of LHX9 have been identified in 46,XY individuals with testicular regression, micropenis and hypospadias. We report a de novo heterozygous missense variant in LHX9 in a girl with 46,XY DSD and finger and toe abnormalities. It was previously predicted that a mutation in LHX9 would not cause extragenital anomalies in light of prior animal studies, but our report adds to the limited knowledge of the phenotype observed in humans with a variant in LHX9. To the best of our knowledge this is the first reported case with this combination of abnormalities.

Upright Biplanar Slot Scanning in Pediatric Orthopedics: Applications, Advantages, and Artifacts.

OBJECTIVE: Digital slot scanning is a relatively new technology that has been used for imaging of pediatric orthopedic conditions such as scoliosis and leg-length discrepancies. This article will review the clinical applications, advantages, and unique artifacts of this new technology. CONCLUSION: Upright biplanar slot scanners acquire high-resolution radiographs simultaneously in two orthogonal planes with reduced radiation dose. Other advantages include a more physiologic weightbearing imaging position, improved Cobb angle measurements, and 3D modeling.

Facial dysmorphism and Limb abnormalities of Fetal Valproate Syndrome.

A neonate born to nonconsanguineous parents was evaluated for dysmorphic features. The neonate was born at term by normal vaginal delivery. The mother has had epilepsy for 12 years and has been on sodium valproate (700 mg/day) since conception and throughout pregnancy. Examination revealed facial dysmorphism, including triangular forehead, sparse arched eyebrows, telecanthus, flat nasal bridge, long thin upper vermilion border, smooth philtrum, and low-set ears. The limb anomalies observed were arachnodactyly, wrist and elbow contractures, clinodactyly, hypoplastic toenails, and overlapping toes. The other dysmorphisms noted were widely spaced nipples and hypospadias. Ultrasonogram (USG) cranium showed bilateral choroid plexus cysts, and USG abdomen revealed bilateral mild hydronephrosis. 2D-Echocardiography revealed a small patent ductus arteriosus (PDA). A diagnosis of fetal valproate syndrome (FVS) was considered, and other differentials, including fetal alcohol syndrome and genetic conditions, were ruled out by a clinical geneticist review. The index neonate is currently on multidisciplinary follow-up. The index neonate had common features of FVS as described in the literature, in addition to wrist and elbow contractures. Apart from the anomalies, there is a significant risk for neurocognitive delay and neurodevelopmental disorders. Postnatally, these babies need multidisciplinary care and neurodevelopmental follow-up. Valproate use for treating epilepsy in pregnant women and women of childbearing age may be restricted, and alternative choices of ASMs with better safety profiles should be preferred. Facial dysmorphism and limb anomalies in fetal valproate syndrome may occur irrespective of the dose of sodium valproate. Fetal valproate syndrome may present with wrist and elbow contractures.

Case Report: Stüve-Wiedemann syndrome-a rare cause of persistent pulmonary hypertension of the newborn.

Introduction: Persistent pulmonary hypertension of the newborn (PPHN) is a life-threatening condition characterized by hypoxemia due to elevated pulmonary vascular resistance. PPHN commonly arises secondary to various underlying conditions, including infection, meconium aspiration, and respiratory distress syndrome. Management includes pulmonary vasodilators, mechanical ventilation, oxygen supplementation, vasopressors, and volume replacement. Stüve-Wiedemann syndrome (SWS), a rare genetic disorder characterized by bone dysplasia, respiratory distress, hyperthermia, and swallowing difficulties, may present with pulmonary hypertension, indicating a poor prognosis. Case description: A term female neonate presented with secondary respiratory failure and severe PPHN of unknown etiology on the second day of life, necessitating intubation. Clinical findings included facial dysmorphia, camptodactyly, skeletal anomalies, and generalized muscular hypotonia. High-frequency oscillation ventilation and surfactant administration yielded marginal improvement. On the third day of life, a severe pulmonary hypertensive crisis necessitated inhaled and systemic pulmonary vasodilators along with volume and catecholamine therapy. Whole exome sequencing revealed a homozygous mutation in the leukemia inhibitory factor receptor (LIFR) gene, consistent with Stüve-Wiedemann syndrome. Discussion/conclusion: The case underscores the importance of considering and prompting evaluation of rare genetic causes in the differential diagnosis of PPHN, especially when other abnormalities are present and conventional therapies prove inadequate. Therapeutic strategies must account for the different pathophysiology of primary PPHN including vascular remodeling, as seen in SWS, which may not respond to pulmonary vasodilators typically employed in secondary PPHN due to vasoconstriction. In this case, the patient responded well to treatment for primary PPHN, but the use of high-frequency oscillation ventilation and surfactant was not helpful.

External validation of a new classification of spinal lipomas based on embryonic stage.

OBJECTIVE: Contention exists regarding appropriate classification and management of spinal lipomas (SLs). Given the heterogeneity of SLs, omissions and overlap between surgically incomparable groups exist in conventional classification systems. The new classification of spinal lipoma (NCSL) recently proposed by Morota et al. delineates morphology by embryological pathogenesis and the resultant operative difficulty. Here, the authors aimed to validate the NCSL by applying it to patients who had been operated on at their institution. METHODS: All children who had undergone resection for SL between 2014 and 2018 were included in this analysis. MRI studies were independently reviewed and classified by three adjudicators. Baseline characteristics, inter-adjudicator agreement, coexisting anomalies and/or malformations, and postoperative outcomes and complications were analyzed. RESULTS: Thirty-six patients underwent surgical untethering for SL: NCSL type 1 in 5 patients (14%), type 2 in 14 patients (39%), type 3 in 4 patients (11%), and type 4 in 13 patients (36%). All classification was agreed on first assignment by the adjudicators. Radical or near-radical resection, which was attempted in all patients, was always possible in those with type 1 and 4 SL, but never in those with type 2 and 3 SL. Neurological stabilization and/or improvement were observed in all patients at the last follow-up. CONCLUSIONS: The NCSL was found to be a logical and reproducible system to apply in this SL population. All cases were successfully classified with a high degree of inter-assessor agreement. Widespread establishment of a commonly adopted and clinically useful classification system will enable clinicians to improve patient selection as well as discussion with patient representatives during the decision-making process.

Characterization of Upper Limb Impairments at Body Function, Activity, and Participation in Persons With Multiple Sclerosis by Behavioral and EMG Assessment: A Cross-Sectional Study.

Background: Multiple sclerosis (MS) is a chronic inflammatory demyelinating and disabling disease which primarily affects individuals in their early life between 20 and 40 years of age. MS is a complex condition, which may lead to a variety of upper limb (UL) dysfunctions and functional deficits. Objective: To explore upper limb impairments at body function, activity, and participation in persons with MS (PwMS) and severe hand dexterity impairment by behavioral and surface electromyography (sEMG) assessments. Methods: This observational cross-sectional study involved 41 PwMS with severe hand dexterity impairment stratified according to the Expanded Disability Status Scale (EDSS) into mild-moderate (n = 17; EDSS, 1-5.5), severe ambulant (n = 15; EDSS, 6-6.5), and severe nonambulant (n = 9; EDSS, 7-9.5). Behavioral outcome measures exploring body function, activity, and participation were administered. The sEMG activity of six upper limb muscles of the most affected side was measured during a reaching task. Results: The most severe group was significantly older and more affected by secondary progressive MS than the other two groups. Positive significant associations between UL deterioration and impairments at different International Classification of Functioning, Disability, and Health domains were noted in the most severe group. The progressive decline in manual dexterity was moderately to strongly associated with the deterioration of the overall UL activity (ρ = 0.72; p < 0.001) and disuse (amount of use ρ = 0.71; p < 0.001; quality of movement ρ = 0.77; p < 0.001). There was a low correlation between manual dexterity and UL function (ρ = 0.33; p = 0.03). The muscle activation pattern investigated by sEMG was characterized by a decrease in modularity and timing delay in the wrist extensor muscles activation in the severe ambulant patients (EDSS, 6-6.5). Similar impairments were observed in the proximal muscles (anterior deltoid) in the more advanced stages (EDSS ≥ 7). Conclusion: Behavioral assessment, together with measures of muscle activation patterns, allows investigating the pathophysiology of UL impairments in PwMS across progressive neurological disability severity to implement task-specific rehabilitation interventions.

Effects of High-intensity Robot-assisted Hand Training on Upper Limb Recovery and Muscle Activity in Individuals With Multiple Sclerosis: A Randomized, Controlled, Single-Blinded Trial.

Background : Integration of robotics and upper limb rehabilitation in people with multiple sclerosis (PwMS) has rarely been investigated. Objective: To compare the effects of robot-assisted hand training against non-robotic hand training on upper limb activity in PwMS. To compare the training effects on hand dexterity, muscle activity, and upper limb dysfunction as measured with the International Classification of Functioning. Methods: This single-blind, randomized, controlled trial involved 44 PwMS (Expanded Disability Status Scale:1.5-8) and hand dexterity deficits. The experimental group (n = 23) received robot-assisted hand training; the control group (n = 21) received non-robotic hand training. Training protocols lasted for 5 weeks (50 min/session, 2 sessions/week). Before (T0), after (T1), and at 1 month follow-up (T2), a blinded rater evaluated patients using a comprehensive test battery. Primary outcome: Action Research Arm Test. Secondary outcomes: Nine Holes Peg Test; Fugl-Meyer Assessment Scale-upper extremity section; Motricity Index; Motor Activity Log; Multiple Sclerosis (MS) Quality of Life-54; Life Habits assessment-general short form and surface electromyography. Results: There were no significant between-group differences in primary and secondary outcomes. Electromyography showed relevant changes providing evidence increased activity in the extensor carpi at T1 and T2. Conclusion: The training effects on upper limb activity and function were comparable between the two groups. However, robot-assisted training demonstrated remarkable effects on upper limb use and muscle activity. https://clinicaltrials.gov NCT03561155.

The Roles of T-Box Genes in Vertebrate Limb Development.

Members of the T-box gene family have diverse roles during embryogenesis and many play critical roles in the developing limb. This is exemplified by the fact that, in humans, mutations in T-box genes are associated with several congenital syndromes that include limb defects as part of their characteristic spectrum of abnormalities. T-box genes encode for evolutionary conserved transcription factors that include both transcriptional activators and repressors. The hallmark of T-box gene members is the presence of the eponymous DNA-binding T-box domain. There are 17 mammalian T-box genes, which based on the sequence homology of the T-box domain, are grouped into five subfamilies, namely, T, Tbx1, Tbx2, Tbx6, and Tbr1. At least nine T-box genes are expressed during limb development with distinct and dynamic expression patterns. All four members of Tbx2 subfamily (Tbx2, Tbx3, Tbx4, Tbx5) and three members of Tbx1 (Tbx1, Tbx15, Tbx18), Brachyury (T) and Eomes (Tbr2) are expressed in the developing limb.

2q31.1 microdeletion syndrome: case report and literature review.

We describe a preterm neonate with bilateral coloboma of the iris, upper and lower limb malformations including rocker bottom feet, camptodactyly, and clinodactyly together with microcephaly and small for gestational age whom cytogenetic diagnosis using SNP microarray detected an interstitial deletion of chromosome 2 between 2q31.1 and 33.1.

Management of congenital femoral deficiency.

Abnormalities that affect the developing human limb range from subtle differences that are of no functional or cosmetic consequence, to complete absence of all limbs. Advances in non-invasive imaging have improved antenatal detection of these conditions and has broadened the options available to prospective parents. This paper considers congenital femoral deficiency and includes an overview of limb bud development and the mechanisms involved in normal growth. The use of ultrasound in antenatal screening and the clinical and radiological features in childhood will be discussed in addition to management including surgical reconstruction and prosthetic use. This should be one component of a multidisciplinary approach to provide the parents of an affected child with balanced information on functional prognosis, management choices and implications for future pregnancies.

Prenatal diagnosis of limb abnormalities: role of fetal ultrasonography.

Fetal ultrasonografy is the most important tool to provide prenatal diagnosis of fetal anomalies. The detection of limb abnormalities may be a complex problem if the correct diagnostic approch is not established. A careful description of the abnormality using the rigth nomenclature is the first step. Looking for other associated abnormalities is the threshold to suspect chromosomal abnormalities or single gene disorder. According to the patogenic point of view, limb abnormalities may be the result of malformation, deformation, or disruption. The prenatal diagnosis and the management of limb abnormalities involve a multidisciplinary team of ostetrician, radiologist/sonologist, clinical geneticist, neonatologist, and orthopedic surgeons to provide the parents with the information regarding etiology of the disorder, prognosis, option related to the pregnancy and recurrence risk for future pregnancies.The aim of this review is to describe the importance of detailed fetal ultrasonography in prenatal diagnosis of limb abnormalities.