Homozygous Null TBX4 Mutations Lead to Posterior Amelia with Pelvic and Pulmonary Hypoplasia.

The development of hindlimbs in tetrapod species relies specifically on the transcription factor TBX4. In humans, heterozygous loss-of-function TBX4 mutations cause dominant small patella syndrome (SPS) due to haploinsufficiency. Here, we characterize a striking clinical entity in four fetuses with complete posterior amelia with pelvis and pulmonary hypoplasia (PAPPA). Through exome sequencing, we find that PAPPA syndrome is caused by homozygous TBX4 inactivating mutations during embryogenesis in humans. In two consanguineous couples, we uncover distinct germline TBX4 coding mutations, p.Tyr113∗ and p.Tyr127Asn, that segregated with SPS in heterozygous parents and with posterior amelia with pelvis and pulmonary hypoplasia syndrome (PAPPAS) in one available homozygous fetus. A complete absence of TBX4 transcripts in this proband with biallelic p.Tyr113∗ stop-gain mutations revealed nonsense-mediated decay of the endogenous mRNA. CRISPR/Cas9-mediated TBX4 deletion in Xenopus embryos confirmed its restricted role during leg development. We conclude that SPS and PAPPAS are allelic diseases of TBX4 deficiency and that TBX4 is an essential transcription factor for organogenesis of the lungs, pelvis, and hindlimbs in humans.

Exacerbation of mild lung disorders to lethal pulmonary hypoplasia by a noncoding hypomorphic SNV in a lung-specific enhancer in trans to the frameshifting TBX4 variant.

Variants involving TBX4 are associated with a wide variety of disorders, including pulmonary arterial hypertension, ischiocoxopodopatellar syndrome (ICPPS)/small patella syndrome (SPS), lethal lung developmental disorders (LLDDs) in neonates, heart defects, and prenatally lethal posterior amelia with pelvic and pulmonary hypoplasia syndrome. The objective of our study was to elucidate the wide variable phenotypic expressivity and incomplete penetrance in a three-generation family with a truncating variant in TBX4. In addition to exome and genome sequencing analyses, a candidate noncoding regulatory single nucleotide variant (SNV) within the lung-specific TBX4 enhancer was functionally tested using an in vitro luciferase reporter assay. A heterozygous frameshift variant c.1112dup (p.Pro372Serfs*14) in TBX4 was identified in patients with mild interstitial lung disease (1), bronchiolitis obliterans (1), recurrent pneumothorax (1), ICPPS/SPS (1), LLDD (2), and in unaffected individuals (4). In two deceased neonates with LLDD, we identified a noncoding SNV rs62069651-C located in trans to the mutated TBX4 allele that reduced the TBX4 promoter activity by 63% in the reporter assay. Our findings provide a functional evidence for the recently reported model of complex compound inheritance in which both TBX4 coding and in trans noncoding hypomorphic variants in the lung-specific enhancer of TBX4 contribute to LLDD.

Identification and Functional Evaluation of a Novel TBX4 Mutation Underlies Small Patella Syndrome.

Small patella syndrome (SPS) is a rare autosomal dominant disorder caused by mutations in TBX4 gene which encodes a transcription factor of FGF10. However, how TBX4 mutations result in SPS is poorly understood. Here, a novel TBX4 mutation c.1241C>T (p.P414L) was identified in a SPS family and series of studies were performed to evaluate the influences of TBX4 mutations (including c.1241C>T and two known mutations c.256G>C and c.743G>T). Results showed that mesenchymal stem cells (MSCs) with stable overexpression of either TBX4 wild-type (TBX4wt) or mutants (TBX4mt) were successfully generated. Immunofluorescence study revealed that both the overexpressed TBX4 wild-type and mutants were evenly expressed in the nucleus suggesting that these mutations do not alter the translocation of TBX4 into the nucleus. Interestingly, MSCs overexpression of TBX4mt exhibited reduced differentiation activities and decreased FGF10 expression. Chromatin immunoprecipitation (ChIP) study demonstrated that TBX4 mutants still could bind to the promoter of FGF10. However, dual luciferase reporter assay clarified that the binding efficiencies of TBX4 mutants to FGF10 promoter were reduced. Taken together, MSCs were firstly used to study the function of TBX4 mutations in this study and the results indicate that the reduced binding efficiencies of TBX4 mutants (TBX4mt) to the promoter of FGF10 result in the abnormal biological processes which provide important information for the pathogenesis of SPS.

Phenotype and outcome of pulmonary arterial hypertension patients carrying a TBX4 mutation.

INTRODUCTION: TBX4 mutation causes small patella syndrome (SPS) and/or pulmonary arterial hypertension (PAH). The characteristics and outcomes of PAH associated with TBX4 mutations are largely unknown. METHODS: We report the clinical, functional, radiologic, histologic and haemodynamic characteristics and outcomes of heritable PAH patients carrying a TBX4 mutation from the French pulmonary hypertension (PH) network. RESULTS: 20 patients were identified in 17 families. They were characterised by a median age at diagnosis of 29 years (0-76 years) and a female to male ratio of three. Most of the patients (70%) were in New York Heart Association (NYHA) functional class III or IV with a severe haemodynamic impairment (median pulmonary vascular resistance (PVR) of 13.6 (6.2-41.8) Wood units). Skeletal signs of SPS were present in 80% of cases. Half of the patients had mild restrictive or obstructive limitation and diffusing capacity of the lung for carbon monoxide (D LCO) was decreased in all patients. High-resolution computed tomography (HRCT) showed bronchial abnormalities, peri-bronchial cysts, mosaic distribution and mediastinal lymphadenopathies. PAH therapy was associated with significant clinical improvement. At follow-up (median 76 months), two patients had died and two had undergone lung transplantation. One-year, three-year and five-year event-free survival rates were 100%, 94% and 83%, respectively. Histologic examination of explanted lungs revealed alveolar growth abnormalities, major pulmonary vascular remodelling similar to that observed in idiopathic pulmonary arterial hypertension (IPAH) and accumulation of cholesterol crystals within the lung parenchyma. CONCLUSION: PAH due to TBX4 mutations may occur with or without skeletal abnormalities across a broad age range from birth to late adulthood. PAH is usually severe and associated with bronchial and parenchymal abnormalities.

Genetics of patella hypoplasia/agenesis.

The patella is a sesamoid bone, crucial for knee stability. When absent or hypoplastic, recurrent knee subluxations, patellofemoral dysfunction and early gonarthrosis may occur. Patella hypoplasia/agenesis may be isolated or observed in syndromic conditions, either as the main clinical feature (Nail-patella syndrome, small patella syndrome), as a clue feature which can help diagnosis assessment, or as a background feature that may be disregarded. Even in the latter, the identification of patella anomalies is important for an appropriate patient management. We review the clinical characteristics of these rare diseases, provide guidance to facilitate the diagnosis and discuss how the genes involved could affect patella development.

Arthroscopic Treatment of Iliopsoas Snapping in Patients With Radiographic Acetabular Dysplasia Using Iliopsoas Fractional Lengthening and Capsular Plication.

PURPOSE: The purpose of this study was to evaluate the greater than 2-year patient-reported outcomes (PROs) and patient satisfaction of patients who were treated with hip arthroscopy for snapping iliopsoas tendons that were painful with concomitant acetabular dysplasia and who underwent iliopsoas lengthening for symptomatic iliopsoas tendon snapping with concomitant capsular plication and treatment of hip impingement. Secondary measures included observation of the change in the Tönnis grade at greater than 2 years' follow-up. METHODS: Between July 2009 and December 2011, data on patients with a lateral center-edge angle (LCEA) of less than 25° (range, 19°-24°) who underwent hip arthroscopy with central-compartment iliopsoas fractional lengthening and capsular plication were prospectively collected and retrospectively reviewed. Interportal capsular repair was performed using between 2 and 5 simple sutures. Patients also underwent procedures to treat hip impingement pathology. All patients had preoperative and minimum 2-year postoperative PRO measures: modified Harris Hip Score, Hip Outcome Score-Activities of Daily Living subscale, Hip Outcome Score-Sports-Specific subscale, and Non-arthritic Hip Score. The visual analog scale score and patient satisfaction with surgery (from 0 to 10) were also collected. Radiographs were analyzed preoperatively and at latest follow-up to assess progression of the Tönnis grade. RESULTS: We analyzed 32 patients who met the inclusion criteria (30 female and 2 male patients; mean age, 25 years). The mean LCEA and anterior center-edge angle were 21.6° and 25.5°, respectively. Four patients required revision arthroscopy for labral retears. Among the 28 patients who did not undergo revision surgery, the modified Harris Hip Score, Hip Outcome Score-Activities of Daily Living subscale, Hip Outcome Score-Sports-Specific subscale, and Non-arthritic Hip Score improved from 68.7 to 83.5, from 64.9 to 86.6, from 71.6 to 86.7, and from 52.6 to 75.8, respectively (P < .001). The visual analog scale score improved from 5.6 preoperatively to 1.9 at latest follow-up (P < .001). The mean patient satisfaction rating was 8.0. There was no radiographic progression of the Tönnis grade at final follow-up. CONCLUSIONS: This study showed that patients with an LCEA of less than 25° and associated painful iliopsoas snapping can be treated by addressing concomitant pathology and performing central-compartment fractional lengthening of the iliopsoas tendon with concomitant capsular plication and have high satisfaction, improvement in PROs, and improved pain scores, without significant progression of osteoarthritis. LEVEL OF EVIDENCE: Level IV, case series.

BIOMECHANICS OF THERAPEUTIC RIDING DURING THE DISEASES OF I-II DEGREE DYSPLASTIC LUMBAR AND STATIC (SHORT LEG) SCOLIOSIS.

The goal of the paper is to substantiate the essence of ridetherapy biomechanics as the pathogenetic therapeutic and prophylactic method at lumbar dysplastic (the I and II degrees) and static (short-legged induced) scoliosis. Uneven lower extremities caused by any reason and asymmetric support induce the change in the arrangement of trochantin to the vertebra and correspondingly the uneven loading of lumbar muscles. The asymmetric strength of lumbar muscles evoked by the change in rotator condition becomes the cause of the formation of scoliosis primary arc which, in its turn, causes a compensatory spinal curvature. In case of dysplastic scoliosis a leading role belongs to the beginning of dystrophic changes in intervertebral discs and its further decentration. At riding position the lower extremities are completely disengaged from the antigravity redistribution, the child is in direct contact with vibrations and jolts coming from the horseback; the antigravity loading is distributed on the muscles of the torso and thus, it creates an opportunity to purposefully affect the correction of the spine. During scoliosis the pathogenic essence of ridetherapy is due to the comprehensiveness of its procedures, expressed in the fact that during one procedure several factors are influenced simultaneously: nucleus pulpous, the torso and iliopsoas muscles, the antigravity system, etc. According to the clinical-functional and radiographic studies carried out in the dynamics on 11-16 years old adolescents it has been established that in those groups where the rehabilitation was conducted in a complex with ridetherapy the authentically higher results were obtained as compared to the groups where the rehabilitation was held using therapeutic exercises and massage.

TBX4 mutations (small patella syndrome) are associated with childhood-onset pulmonary arterial hypertension.

BACKGROUND: Childhood-onset pulmonary arterial hypertension (PAH) is rare and differs from adult-onset disease in clinical presentation, with often unexplained mental retardation and dysmorphic features (MR/DF). Mutations in the major PAH gene, BMPR2, were reported to cause PAH in only 10-16% of childhood-onset patients. We aimed to identify more genes associated with childhood-onset PAH. METHODS: We studied 20 consecutive cases with idiopathic or heritable PAH. In patients with accompanying MR/DF (n=6) array-comparative genomic hybridisation analysis was performed, with the aim of finding common deletion regions containing candidate genes for PAH. Three patients had overlapping deletions of 17q23.2. TBX2 and TBX4 were selected from this area as candidate genes and sequenced in all 20 children. After identifying TBX4 mutations in these children, we subsequently sequenced TBX4 in a cohort of 49 adults with PAH. Because TBX4 mutations are known to cause small patella syndrome (SPS), all patients with newly detected TBX4 mutations were screened for features of SPS. We also screened a third cohort of 23 patients with SPS for PAH. RESULTS: TBX4 mutations (n=3) or TBX4-containing deletions (n=3) were detected in 6 out of 20 children with PAH (30%). All living patients and two parents with TBX4 mutations appeared to have previously unrecognised SPS. In the adult PAH-cohort, one TBX4 mutation (2%) was detected. Screening in the cohort of (predominantly adult) SPS patients revealed no PAH. CONCLUSIONS: These data indicate that TBX4 mutations are associated with childhood-onset PAH, but that the prevalence of PAH in adult TBX4 mutation carriers is low.

A novel SOX9 H169Q mutation in a family with overlapping phenotype of mild campomelic dysplasia and small patella syndrome.

The phenotypic similarities have been demonstrated between non-lethal campomelic dysplasia (CD) and small patella syndrome (SPS), in which different genetic defects have been identified. We report on a familial case of skeletal dysplasia with overlapping phenotype of mild CD and SPS, including defective ischio-pubic ossification, elongated femoral neck, hypoplastic patellae, and increased space between the first and the second toes (sandal gap). Direct sequencing analysis demonstrated a novel missense mutation (p.H169Q) within the coding region of the SOX9 gene and negative for TBX4 mutations. Functional analysis of the p.H169Q mutant revealed reduced but not fully abolished transactivation capacity of the mutated protein. Retained residual SOX9 function might contribute to an extremely mild CD phenotype in the present cases. © 2013 Wiley Periodicals, Inc.

Prevalence of clinical hip abnormalities in haemophilia A and B: an analysis of the UDC database.

Clinical hip abnormalities, secondary to recurrent joint and/or muscle bleeding in persons with haemophilia, have not been well characterized and have the potential for significant morbidity. We aimed to examine the prevalence of clinical hip abnormalities in the US haemophilia population and to explore associations between these findings and putative risk factors. We conducted a study of hip abnormalities of 8192 subjects aged 2-69 years with haemophilia A and haemophilia B (54% of haemophilia A and haemophilia B are severe) currently enrolled in the Universal Data Collection (UDC) database. Associations between hip abnormality and type/severity of haemophilia A/B, current age, history of high-titre (≥ 5 BU) inhibitor (HTinh), concomitant ankle (AA) and knee arthropathy (KA), overweight and obesity and prophylaxis were examined using logistic regression. Overall prevalence of hip abnormality at the last recorded UDC visit for all subjects was 16.7%. Haemophilia A (aOR = 1.3, 1.0-1.4), severe haemophilia (aOR = 1.3, 1.0-1.5), a history of HTinh (aOR = 1.4, 1.1-1.7), and concomitant AA (aOR = 1.7, 1.4-1.9) were each independently associated with hip abnormality. Older age (45-69 years) was significantly associated with hip abnormality prevalence only in subjects with KA (aOR = 3.4, 1.9-5.9). The presence of overweight (aOR = 1.4, 1.1-1.8) and obesity (aOR = 2.1, 1.6-2.8) was associated with hip abnormality only among subjects without KA. Hip abnormality prevalence was not influenced by prophylaxis (aOR = 0.9, 0.8-1.1). These data suggest that hip abnormalities in US patients with haemophilia are associated with haemophilia severity and type, HTinh, concomitant AA and, depending on the presence or absence of KA, advancing age and obesity.

General ultrasound screening reduces the rate of first operative procedures for developmental dysplasia of the hip: a case-control study.

OBJECTIVES: To assess the effectiveness of general ultrasound screening to prevent first operative procedures of the hip. STUDY DESIGN: We conducted a case-control study in a population in which general ultrasound screening supplementing clinical screening is recommended and offered free of charge for all children. Participation in ultrasound screening before week 7 as recommended in Germany was the exposure of interest. Case ascertainment was based on active surveillance in orthopedic hospitals. The case definition was: first operative procedure for developmental dysplasia of the hip (closed reduction, open reduction, or osteotomy) in children >9 weeks old and <5 years old and born between 1996 and 2001. Control subjects from the same birth cohorts were recruited in telephone surveys. RESULTS: Cases of first operative procedures for developmental dysplasia of the hip (n = 446) were compared with 1173 control subjects for ultrasound screening. Effectiveness of ultrasound screening to prevent first operative procedures for developmental dysplasia of the hip was estimated as 52% (95% CI, 32-67). Effectiveness did not vary substantially for closed and open reductions and osteotomy. CONCLUSIONS: General ultrasound screening reduces the rate of operative procedures for developmental dysplasia of the hip; the impact on developmental dysplasia of the hip. Treatment rates and avascular necrosis need further assessment to balance the benefit against potential overtreatment and adverse effects.

Association between cam-type deformities and magnetic resonance imaging-detected structural hip damage: a cross-sectional study in young men.

OBJECTIVE: Femoroacetabular impingement may be a risk factor for hip osteoarthritis in men. An underlying hip deformity of the cam type is common in asymptomatic men with nondysplastic hips. This study was undertaken to examine whether hip deformities of the cam type are associated with signs of hip abnormality, including labral lesions and articular cartilage damage, detectable on magnetic resonance imaging (MRI). METHODS: In this cross-sectional, population-based study in asymptomatic young men, 1,080 subjects underwent clinical examination and completed a self-report questionnaire. Of these subjects, 244 asymptomatic men with a mean age of 19.9 years underwent MRI. All MRIs were read for cam-type deformities, labral lesions, cartilage thickness, and impingement pits. The relationship between cam-type deformities and signs of joint damage were examined using logistic regression models adjusted for age and body mass index. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were determined. RESULTS: Sixty-seven definite cam-type deformities were detected. These deformities were associated with labral lesions (adjusted OR 2.77 [95% CI 1.31, 5.87]), impingement pits (adjusted OR 2.9 [95% CI 1.43, 5.93]), and labral deformities (adjusted OR 2.45 [95% CI 1.06, 5.66]). The adjusted mean difference in combined anterosuperior femoral and acetabular cartilage thickness was -0.19 mm (95% CI -0.41, 0.02) lower in those with cam-type deformities compared to those without. CONCLUSION: Our findings indicate that the presence of a cam-type deformity is associated with MRI-detected hip damage in asymptomatic young men.

A second patient with Tsukahara syndrome: type A1 brachydactyly, short stature, hearing loss, microcephaly, mental retardation and ptosis.

In 1989, Tsukahara and colleagues described a single female with a provisionally unique pattern of malformation consisting of low intelligence, short stature, brachydactyly type A1, and characteristic facial features. We report on a second patient confirming Tsukahara syndrome as an established entity.

Right hip and pelvic pain.

Follow-up imaging confirmed a clinical suspicion.

Identifying pathogenic variants in the Follistatin-like 1 gene (FSTL1) in patients with skeletal and atrioventricular valve disorders.

BACKGROUND: Follistatin-like 1 (Fstl1) is a glycoprotein expressed throughout embryonic development. Homozygous loss of Fstl1 in mice results in skeletal and respiratory defects, leading to neonatal death due to a collapse of the trachea. Furthermore, Fstl1 conditional deletion from the endocardial/endothelial lineage results in postnatal death due to heart failure and profound atrioventricular valve defects. Here, we investigated patients with phenotypes similar to the phenotypes observed in the transgenic mice, for variants in FSTL1. METHODS: In total, 69 genetically unresolved patients were selected with the following phenotypes: campomelic dysplasia (12), small patella syndrome (2), BILU (1), and congenital heart disease patients (54), of which 16 also had kyphoscoliosis, and 38 had valve abnormalities as their main diagnosis. Using qPCR, none of 69 patients showed copy number variations in FSTL1. The entire gene body, including microRNA-198 and three validated microRNA-binding sites, were analyzed using Sanger sequencing. RESULTS: No variants were found in the coding region. However, 8 intronic variants were identified that differed significantly in their minor allele frequency compared to controls. Variant rs2272515 was found to significantly correlate (p < 0.05) with kyphoscoliosis. CONCLUSION: We conclude that pathogenic variants in FSTL1 are unlikely to be responsible for skeletal or atrioventricular valve anomalies in humans.

Phenotypic variation in trismus-pseudocamptodactyly syndrome caused by a recurrent MYH8 mutation.

We report a 20-year-old man with trismus-pseudocamptodactyly (TPS) syndrome who was found to have the same MYH8 mutation, p.R674Q, described in previous families with TPS syndrome and in one family with a Carney complex variant, trismus and pseudocamptodactyly. This patient had facial asymmetry, ptosis and downslanting palpebral fissures and multiple joint involvement, with bilateral hip dysplasia, reduced elbow supination, vertical tali and talipes in addition to the classical findings of trismus and pseudocamptodactyly. These findings broaden the phenotype associated with p.R674Q mutations and support the use of MYH8 testing in patients with a clinical diagnosis of TPS syndrome.

Dígito pélvico como hallazgo incidental y posibles diagnósticos diferenciales / Pelvic digit as an incidental finding and possible differential diagnoses

El dígito pélvico es un tipo de anomalía congénita benigna poco frecuente, que se localiza en la región coxofemoral, en relación con el ilion.A pesar de que suele ser asintomático, es importante conocer su existencia, así como los posibles diagnósticos diferenciales, ya que se puede encontrar como un hallazgo incidental en la radiografía simple.Se presenta el caso de un hombre, de 58 años, que acude a su médico de Atención Primaria (AP) por artralgias generalizadas, quien observa en la radiografía simple de cadera un hallazgo inusual, por lo que interconsulta al servicio de Radiodiagnóstico, donde se realiza el diagnóstico de dígito pélvico.(AU)

The pelvic digit is a rare benign congenital abnormality, located in the hip region, in regard to the ilium.Although usually asymptomatic, it is important to be aware of its existence as well as the possible differential diagnoses since it can be found as an incidental finding on plain x-ray.We report the case of a 58-year-old man who presented to his primary care physician because of generalized arthralgia. He observed an unusual finding on plain x-ray of the hip, whereby he consulted the radiology department, where pelvic digit was diagnosed.(AU)

Case Report of Clinical Vignette: Osteopetrosis.

INTRODUCTION: Osteopetrosis is a connective tissue disorder resulting from abnormally dense bone predisposing patients to fracture. The clinical pattern of fractures across time and space as well as suggestive radiographic findings usually raises diagnostic suspicion. Multiple genetic mutations resulting in dysfunctional osteoclasts have been implicated in the pathogenesis of osteopetrosis with variable inheritance patterns. In severe cases, usually inherited in an autosomal recessive pattern, the medullary cavity important in the production of normal blood cell progenitors is replaced by defective endochondral bone, leading to pancytopenia and consequential extramedullary hematopoiesis. MATERIALS AND METHODS: This is a case report from a patient presenting to Naval Medical Center San Diego, a large Military Treatment Facility constituting a regional referral center for Navy Medicine West and serving approximately 250,000 eligible patients with more than 6,200 military and civilian staff. The genetic analysis was performed by Connective Tissue Gene Tests (CTGT) using the CTGT Osteopetrosis NextGen sequencing panel, consisting of 13 genes associated with osteopetrosis. A literature review was performed using PUBMED and Google Scholar to identify information on osteopetrosis and mutation implications. RESULTS: We present a 19-year-old male with clinical osteopetrosis resulting from compound heterozygosity of several mutated alleles within the PLEKHM1 gene, which is important to endosomal and lysosomal vesicular function. To date, most mutations discovered involve genes coding for intracellular enzymes, like carbonic anhydrase, or cell surface transporters, such as the osteoclast H+-ATPase proton pump and the chloride channel, engaged in the acidification of bone at the interface of the osteoclastic ruffled border and the bone matrix. This case represents one of the few reports of inherited defects within the PLEKHM1 gene, resulting in defective osteoclastic ruffled border formation and consequential inadequate bone resorption. CONCLUSIONS: This patient's lack of hematologic deficiencies and survival into adulthood portend an improved long-term prognosis and may infer prognostic insight in future cases with similar genetic abnormalities. In patients presenting with skeletal abnormalities and pathologic fractures in early adulthood, the clinician should consider osteopetrosis as a potential explanatory mechanism. Genetic characterization can elucidate cellular pathophysiology and potentially guide treatment modalities. Patients are typically managed with lifestyle adjustments limiting traumatic fracture and antiresorptive medications, typified by the bisphosphonate class. Since osteoclasts derive from a hematopoietic precursor, the only definitive curative therapy present is hematopoietic stem cell transplant. In the future, novel genomic level modulation may confer the ability to correct underlying point mutations and spare individuals from the morbidity associated with bone marrow transplant.