Novel compound heterozygous pathogenic variants in ASCC1 in a Chinese patient with spinal muscular atrophy with congenital bone fractures 2 : Evidence supporting a "Definitive" gene-disease relationship.

BACKGROUND: A very limited spectrum of ASCC1 pathogenic variants had been reported in six (mostly consanguineous) families with spinal muscular atrophy with congenital bone fractures 2 [OMIM #616867] since 2016. METHODS: A proband from a non-consanguineous Chinese family presented with neonatal severe hypotonia, respiratory distress, muscle weakness, and atrophy, as well as congenital bone fractures was performed by exome sequencing. RESULTS: A compound heterozygosity of a nonsense (c.932C>G,p.Ser311Ter) and an exon 5 deletion in ASCC1 segregating with phenotypes was detected, both variants are novel and pathogenic. Since ASCC1 is a relatively new disease gene, we performed the gene curation by ClinGen SOP. The existing evidence is sufficient to support a "Definitive" level of disease-gene relationship. CONCLUSION: This case report expended the mutation spectrum of ASCC1 and support the notion that this novel disease also occurs in outbreed populations and this is a rare disease but may still be underdiagnosed due to its perinatal lethal outcomes.

Novel ASCC1 mutations causing prenatal-onset muscle weakness with arthrogryposis and congenital bone fractures.

BACKGROUND: The activating signal cointegrator 1 (ASC-1) complex acts as a transcriptional coactivator for a variety of transcription factors and consists of four subunits: ASCC1, ASCC2, ASCC3 and TRIP4. A single homozygous mutation in ASCC1 has recently been reported in two families with a severe muscle and bone disorder. OBJECTIVE: We aim to contribute to a better understanding of the ASCC1-related disorder. METHODS: Here, we provide a clinical, histological and genetic description of three additional ASCC1 families. RESULTS: All patients presented with severe prenatal-onset muscle weakness, neonatal hypotonia and arthrogryposis, and congenital bone fractures. The muscle biopsies from the affected infants revealed intense oxidative rims beneath the sarcolemma and scattered remnants of sarcomeres with enlarged Z-bands, potentially representing a histopathological hallmark of the disorder. Sequencing identified recessive nonsense or frameshift mutations in ASCC1, including two novel mutations. CONCLUSION: Overall, this work expands the ASCC1 mutation spectrum, sheds light on the muscle histology of the disorder and emphasises the physiological importance of the ASC-1 complex in fetal muscle and bone development.

Contralateral Involvement of Congenital Muscular Torticollis and Clavicular Fracture.

Congenital muscular torticollis (CMT) is known to concur with some conditions such as developmental dysplasia of the hip or brachial plexus injury, which gives us some insights for pathogenesis of CMT. Although clavicular fracture is the most common fracture in newborns, little is known about concurrence of CMT and clavicular fracture. Our clinical experience led us to realize that concurrence of CMT and clavicular fracture tended to occur on the contralateral side for each other rather than the ipsilateral side. This study aimed to verify contralateral concurrence of CMT and clavicular fracture. This is a retrospective cohort study in a tertiary hospital, including 996 subjects with CMT. Concurrent clavicular fracture was found in 20 of 996 subjects with CMT, with the concurrence rate being 2.01%. Concurrent clavicular fracture and clavicular fracture occurred on the contralateral side for each other in 18 subjects (90%) rather than the ipsilateral side. This contralateral concurrence between side of CMT and clavicular fracture was significant (P = 0.001), with an odds ratio of 81 (P = 0.0032). Concurrent clavicular fracture and clavicular fracture seem to occur significantly more on the contralateral side for each other. Underlying mechanism for consistent contralateral concurrence needs to be verified in the near future.

[PREPARATIONS OF PAMIDRONOVIC ACID IN COMPLEX TREATMENT ON OSTEOGENESIS IMPERFECTA].

Modern view of drug therapy in the complex treatment of orthopedic manifestations of osteogenesis imperfecta (OI) was submitted. Developed and tested system of drug correction of structural and functional state of bone tissue (BT) using drugs pamidronovic acid, depending on osteoporosis severity and type of disease. Such therapy is appropriate to apply both independently and in conjunction with surgery to correct deformations of long bones of the lower extremities. Effectiveness and feasibility of the proposed methods of drug therapy was proved, most patients resume features walking and support.

X-linked spinal muscular atrophy (SMAX2) caused by de novo c.1731C>T substitution in the UBA1 gene.

Infantile X-linked spinal muscular atrophy (SMAX2) is a rare form of spinal muscular atrophy manifesting as severe hypotonia, areflexia, arthrogryposis, facial weakness and cryptorchidism, and frequently accompanied by bone fractures. We present a male patient with SMAX2 who presented with typical symptoms at birth, preceded by reduced fetal movements in the second and third trimesters of pregnancy. Clinical examination revealed a myopathic face with a characteristic tent-shaped open mouth, tongue fibrillations, profound muscle weakness, areflexia, multiple contractures, mild skeletal abnormalities and cryptorchidism. In the first days of the patient's life, fractures of the right femur and right humerus were found; however, calcium-phosphate metabolism and densitometric examination were normal. Molecular analysis revealed a de novo c.1731C>T substitution in the UBA1 gene, which was localized in exon 15, the specific hot spot for mutation.

Neonatal outcome of macrosomic infants: an analysis of a two-year period.

OBJECTIVE: To assess the neonatal outcome of macrosomic neonates in uncomplicated, singleton, term deliveries. STUDY DESIGN: A retrospective analysis was performed on 5738 live-born term neonates born in the period 2008-2009. The neonatal outcomes were compared between two birth weight (BW) groups: the macrosomic neonates born with BW≥4000g and a control group: 2500-3999g. There were 410 (7.1%) neonates in the macrosomic group, 4757 (82.9%) in the control group, while 571 (10.0%) were less than 2500g at birth. A correlation analysis of two subgroups of the macrosomic neonates (4000-4499g vs. ≥4500g) was also carried out. RESULTS: The rate of caesarean section (CS) was significantly higher in the macrosomic group as compared with the control group (49.3% vs. 39.9%), as were the prevalences of hypoglycaemia (6.1% vs. 2.9%), adrenal haemorrhage (0.98% vs. 0.15%) and the male to female ratio (2.15 vs. 0.95). The rate of icterus was significantly higher in the control group (30.4% vs. 18.5%). The macrosomic subgroups were similar in many aspects, but we found significantly more neonates in the higher weight subgroup as regards a low Apgar score, clavicle fracture and the need for intensive care. CONCLUSIONS: The macrosomic infants were born in good general condition, although those with BW ≥4500g more frequently had an adverse outcome. The macrosomic and control groups' data revealed significant differences in the rate of CS, the male to female ratio, hypoglycaemia and adrenal haemorrhage.

Bilateral acromial fractures in a neonate with epileptic encephalopathy.

We present a case of a newborn male with seizures who on subsequent radiographs was shown to have bilateral acromial fractures. These are uncommon fractures and are described in association with nonaccidental injury (NAI). However, in this case NAI was thought unlikely due to continuous hospitalisation of the boy. The possible aetiologies are discussed.

SUNCT syndrome or first division trigeminal neuralgia associated with cerebellar hypoplasia.

Short-lasting unilateral neuralgiform headache (SUNCT) and first division trigeminal neuralgia (TN) are rare and very similar periorbital unilateral pain syndromes. Few cases of SUNCT are associated with posterior skull lesions. We describe a 54-year-old man with symptoms compatible with both the previous painful syndromes, associated with a small posterior skull and a cerebellar hypoplasia. The short height and the reported bone fractures could be compatible with a mild form of osteogenesis imperfecta, previously described in one case associated with SUNCT. However, a hypoplastic posterior cranial fossa characterizes also Chiari I malformation. The difficult differential diagnosis between SUNCT and TN and their relation with posterior skull malformations is debated.

Osteogenesis imperfecta in the neonate.

Osteogenesis imperfecta is a rare heterozygous disorder of collagen production. It is characterized by osteopenia, blue sclera, bone deformities, and progressive hearing loss. Some infants are diagnosed prenatally, whereas others are diagnosed much later in life. This article provides an overview of the disorder and discusses the etiologic origins of the syndrome. A guide for a systematic physical assessment is presented to enhance the early recognition of the disorder. Pictorial examples are provided to enhance the understanding of the wide spectrum of osteogenesis imperfecta. A discussion on treatment and clinical implications, with an emphasis on family support, is provided.

Congenital bone fractures in spinal muscular atrophy: functional role for SMN protein in bone remodeling.

Spinal muscular atrophy is the second most common fatal childhood disorder. Core clinical features include muscle weakness caused by degenerating lower motor neurons and a high incidence of bone fractures and hypercalcemia. Fractures further compromise quality of life by progression of joint contractures or additional loss of motor function. Recent observations suggest that bone disease in spinal muscular atrophy may not be attributed entirely to lower motor neuron degeneration. The presence of the spinal muscular atrophy disease-determining survival motor neuron gene (SMN), SMN expression, and differential splicing in bone-resorbing osteoclasts was recently discovered. Its ubiquitous expression and the differential expression of splice variants suggest that SMN has specific roles in bone cell function. SMN protein also interacts with osteoclast stimulatory factor. Mouse models of human spinal muscular atrophy disease suggest a potential role of SMN protein in skeletal development. Dual energy x-ray absorptiometry analysis demonstrated a substantial decrease in total bone area and poorly developed caudal vertebra in the mouse model. These mice also had pelvic bone fractures. Studies delineating SMN signaling mechanisms and gene transcription in a cell-specific manner will provide important molecular insights into the pathogenesis of bone disease in children with spinal muscular atrophy. Moreover, understanding bone remodeling in spinal muscular atrophy may lead to novel therapeutic approaches to enhance skeletal health and quality of life. This article reviews the skeletal complications associated with spinal muscular atrophy and describes a functional role for SMN protein in osteoclast development and bone resorption activity.

Nontraumatic disorders of the clavicle.

Other than those resulting from trauma and arthritis, disorders of the clavicle are uncommon. Some nontraumatic disorders are found only in infancy and childhood, such as birth fracture, infantile cortical hyperostosis, congenital pseudarthrosis, cleidocranial dysplasia, and short clavicle syndrome. Other nontraumatic disorders occur in both children and adults; these include anterior subluxation of the sternoclavicular joint, Friedrich's disease, hypertrophic osteitis, chronic multifocal periosteitis and arthropathy, and osteomyelitis. Some nontraumatic clavicular disorders are found only in adults, such as distal osteolysis. Because the description and nomenclature of these disorders arise from several medical disciplines, they often are confusing. Until clear, distinguishing features are described, it is advisable to combine some of the entities. This is especially true of the nonsuppurative inflammatory disorders of the clavicle, which appear to fall under the heading of spondyloarthropathy. Treatment varies by disorder and may include symptomatic and expectant management, drug therapy, and nonsurgical or surgical treatment.

A case of brittle bone disease.

Brittle bone disease--synonym, osteogenesis imperfecta is a rare genetic disorder of collagen synthesis associated with broad spectrum of musculoskeletal problem, where bones break easily. Recently we got a case of OI, whose name is Babu, 3 days old, full term bay with uneventful home delivery. The baby had multiple fractures in all the extremities with deformities with blue sclera with bilateral inguinal hernia. Other systems were found normal. On 10th day of life he was operated for inguinal hernia with satisfactory postoperative recovery and subsequently he was referred to the orthopedic department for further management.

Spinal muscular atrophy with congenital fractures: postmortem analysis.

We present a male infant with congenital fractures and features typical of spinal muscular atrophy. Mid-shaft fractures of the left humerus and both femurs occurred in utero. The patient died at 8 months of age following recurrent respiratory tract infections. His peripheral electrophysiologic studies were consistent with anterior horn cell disease. Molecular genetic studies were negative for the SMN gene. At autopsy, extensive anterior horn cell loss was present. There was extensive disease of skeletal muscle with relative sparing of the diaphragm. This patient represents a further case of this rare and fatal disease.

Severe spinal muscular atrophy variant associated with congenital bone fractures.

Infantile autosomal recessive spinal muscular atrophy (type I) represents a lethal disorder leading to progressive symmetric muscular atrophy of limb and trunk muscles. Ninety-six percent cases of spinal muscular atrophy type I are caused by deletions or mutations in the survival motoneuron gene (SMNI) on chromosome 5q11.2-13.3. However, a number of chromosome 5q-negative patients with additional clinical features (respiratory distress, cerebellar hypoplasia) have been designated in the literature as infantile spinal muscular atrophy plus forms. In addition, the combination of severe spinal muscular atrophy and neurogenic arthrogryposis has been described. We present clinical, molecular, and autopsy findings of a newborn boy presenting with generalized muscular atrophy in combination with congenital bone fractures and extremely thin ribs but without contractures.

Spinal muscular atrophy variant with congenital fractures.

A single report of brothers born to first-cousin parents with a form of acute spinal muscular atrophy (SMA) and congenital fractures suggested that this combination represented a distinct form of autosomal recessive SMA. We describe a boy with hypotonia and congenital fractures whose sural nerve and muscle biopsies were consistent with a form of spinal muscular atrophy. Molecular studies identified no abnormality of the SMN(T) gene on chromosome 5. This case serves to validate the suggestion of a distinct and rare form of spinal muscular atrophy while not excluding possible X-linked inheritance.

Lethal syndrome of slender bones, intrauterine fractures, characteristics facial appearance, and cataracts, resembling Hallermann-Streiff syndrome in two sibs.

We report on a family in which 1 males infant who died neonatally and 1 female fetus at 29 weeks of gestation had an identical condition resembling Hallermann-Streiff syndrome. The long bones were slender with a few fractures, the skull was underossified, and the face was characteristic of Hallermann-Streiff syndrome. Bilateral cataracts were identified in the male. We regard the condition in this family as a severe form of Hallermann-Streiff syndrome, which appears to have been lethal, at least in the liveborn male. This syndrome is usually sporadic. Recurrence in sibs suggests the possibility of autosomal-recessive inheritance, or of a dominant mutation with parental mosaicism.