GLYT1 encephalopathy: Further delineation of disease phenotype and discussion of pathophysiological mechanisms.

GLYT1 encephalopathy is a form of glycine encephalopathy caused by disturbance of glycine transport. The phenotypic spectrum of the disease has not yet been completely described, as only four unrelated families with the disorder have been reported to date. Common features of affected patients include neonatal hypotonia, respiratory failure, encephalopathy, myoclonic jerks, dysmorphic features, and musculoeskeletal anomalies. All reported affected patients harbor biallelic genetic variants in SLC6A9. SNP array together with Sanger sequencing were performed in a newborn with arthrogryposis and severe neurological impairment. The novel genetic variant c.997delC in SLC6A9 was detected in homozygous state in the patient. At protein level, the predicted change is p.(Arg333Alafs*3), which most probably results in a loss of protein function. The variant cosegregated with the disease in the family. A subsequent pregnancy with ultrasound anomalies was also affected. The proband presented the core phenotypic features of GLYT1 encephalopathy, but also a burst suppression pattern on the electroencephalogram, a clinical feature not previously associated with the disorder. Our results suggest that the appearance of this pattern correlates with higher cerebrospinal fluid glycine levels and cerebrospinal fluid/plasma glycine ratios. A detailed discussion on the possible pathophysiological mechanisms of the disorder is also provided.

Genetics of neuromuscular fetal akinesia in the genomics era.

Fetal hypokinesia or akinesia encompasses a broad spectrum of disorders, united by impaired movement in utero. Often, the underlying aetiology is genetic in origin, affecting part of the neuromuscular system. The affordable and high-throughput nature of next-generation DNA sequencing has led to an explosion in disease gene discovery across rare diseases, including fetal akinesias. A genetic diagnosis has clinical utility as it may affect management and prognosis and informs recurrence risk, facilitating family planning decisions. More broadly, knowledge of disease genes increasingly allows population-based preconception carrier screening, which has reduced the incidence of recessive diseases in several populations. Despite gains in knowledge of the genetics of fetal akinesia, many families lack a genetic diagnosis. In this review, we describe the developments in Mendelian genetics of neuromuscular fetal akinesia in the genomics era. We examine genetic diagnoses with neuromuscular causes, specifically including the lower motor neuron, peripheral nerve, neuromuscular junction and muscle.

Survival among children with "Lethal" congenital contracture syndrome 11 caused by novel mutations in the gliomedin gene (GLDN).

Biallelic GLDN mutations have recently been identified among infants with lethal congenital contracture syndrome 11 (LCCS11). GLDN encodes gliomedin, a protein required for the formation of the nodes of Ranvier and development of the human peripheral nervous system. We report six infants and children from four unrelated families with biallelic GLDN mutations, four of whom survived beyond the neonatal period into infancy, childhood, and late adolescence with intensive care and chronic respiratory and nutritional support. Our findings expand the genotypic and phenotypic spectrum of LCCS11 and demonstrate that the condition may not necessarily be lethal in the neonatal period.

Oligohydramnios sequence revisited in relationship to arthrogryposis, with distinctive skin changes.

Thirty cases of arthrogryposis associated with longstanding oligohydramnios were identified among 2,500 cases of arthrogryposis (1.2%) and were reviewed for clinical features and natural history. None had renal agenesis or renal disease. Twenty-two had a history of known rupture of membranes. Only 50% had pulmonary hypoplasia at birth and only two died (7%). Sixty percent (18/30) seemed to have their multiple congenital contractures (MCC) primarily on the basis of compression related to the longstanding oligohydramnios and responded well to physical therapy. On average they did not have intrauterine growth restriction. "Potter" facies and remarkable skin changes were present in all. An excess of males was observed in spite of the lack of genitourinary anomalies.

Arthrogryposis multiplexa congenita: an epidemiologic study of nearly 9 million births in 24 EUROCAT registers.

OBJECTIVE: To examine the occurrence of arthrogryposis multiplex congenita (AMC) in Europe and to identify possible risk factors. STUDY DESIGN: Retrospective population-based epidemiological study using EUROCAT congenital anomaly registries. The study population included all cases of AMC (based on WHO ICD-9 or ICD-10 codes) that were livebirths (LB), fetal deaths (FD) from 20 weeks gestation and underwent termination of pregnancy for fetal anomaly (TOPFA), 1980-2006. RESULTS: Among 8.9 million births covered by 24 EUROCAT congenital anomaly registries, 757 AMC cases were reported. This gives a prevalence of 8.5 per 100,000. Five hundred and four (67%) AMC cases were LB, 199 (26%) cases were TOPFA, and FD occurred in 54 (7%) cases. First week survival status was known for 381 of the 504 LB (76%), of whom 87 (23%) died within the first week of life. Perinatal mortality associated with AMC was 32%. Two hundred and eighty-two (37%) cases had isolated AMC, 90 (12%) had additional syndrome or chromosomal anomalies and 385 (51%) had other major malformations. The same or similar anomaly was reported in 13% of siblings and in 12% of the mother's own family background. Information on prenatal testing was available for 521 cases of which 360 tested positive for a congenital anomaly, representing a sensitivity of 69%. Information on maternal illness before and during pregnancy and medication use in the first trimester was available for approximately a third of the mothers, of whom the vast majority reported no maternal illness or medication use. CONCLUSION: AMC is a rare occurrence, with a reported prevalence of 1:12,000. In this study, while information on potential risk factors such as maternal disease or maternal use of drugs was limited, they did not appear to be associated with the occurrence of AMC. AMC was lethal in a third of cases, either in utero or during the first week of life, although this may not be solely attributed to AMC as most cases had additional malformations.

Lethal congenital contracture syndrome (LCCS) and other lethal arthrogryposes in Finland--an epidemiological study.

Arthrogryposis multiplex congenita is a heterogeneous group of disorders characterized by multiple contractures with an estimated frequency of 1 in 3,000 births. With improving diagnostic methods, increasing numbers of fetuses with arthrogryposis are found. The pathogenetic mechanisms are relatively well known but the epidemiology and genetics of the prenatally lethal forms of arthrogryposis are less well known. In this study we collected all cases of a multiple contractures diagnosed in Finland during 1987-2002 including live born infants, stillbirths, and terminated pregnancies. Ninety-two cases of 214 suffered intrauterine demise (68 selective pregnancy terminations and 24 stillbirths) and 58 died in infancy. In 141 out of these cases the diagnosis could be included within lethal arthrogryposes, with a prevalence of 1 in 6,985 (1.43/10,000) births. Of these, 59 had spinal cord pathology at autopsy and thus were of neurogenic origin. Thirty-nine cases had lethal congenital contracture syndrome (LCCS) clinically characterized by total immobility of the fetus at all ultrasound examinations (12 weeks or later), multiple joint contractures in both upper and lower limbs, hydrops, and fetal death before the 32nd week of pregnancy. LCCS is noted as a unique Finnish disorder with a prevalence of 1 in 25,250 (0.40/10,000) births and is a major cause of lethal arthrogryposis in Finland.

Artrogryposis multiplex congenita -- a rare fetal condition caused by maternal myasthenia gravis.

OBJECTIVES: To look at the occurrence of arthrogryposis multiplex congenita in newborn of mothers with myasthenia gravis (MG) and factors connected to this. MATERIAL AND METHODS: We retrospectively studied 176 births by 79 MG mothers, recorded in the Medical Birth Registry of Norway (MBRN). Four (2.2%) newborns (including one pair of twins) born with severe skeletal anomalies were identified. RESULTS: All four children died. Three had findings consistent with arthrogryposis multiplexa congenita (AMC), one had a fetal akinesia deformation sequence (FADS). The mother of the child with FADS had previously given birth to a child with neonatal MG. She was now in complete MG remission. The mother of the twins with AMC later gave birth to a child with neonatal MG. CONCLUSION: Siblings of an affected child -- either with neonatal MG or AMC -- have an increased risk to develop either neonatal MG or AMC. As this appears to be independent of the MG mother's clinical state, it is important to discuss previous pregnancy outcomes with all female MG patients.

[Severe neonatal myasthenia with arthrogryposis]. / Myasthénie néonatale sévère avec arthrogrypose: à propos d'un cas et revue de la littérature.

Maternal myasthenia gravis has been associated with the presence of neonatal myasthania and sometimes fetal congenital anomalies. The purpose of this paper is to present an infant with multiple deformations born to a mother with myasthenia gravis. The infant presented with arthrogryposis multiplex and pulmonary hypoplasia. The new born died within the first day of life. Twenty-seven other cases of neonatal myasthenia with arthrogryposis have been reported. Twenty-two of them were stillborn or died. The surviving children needed ventilatory assistance for a long period.

Infant with high arched palate, bell-shaped chest, joint contractures, and intrauterine fractures.

A case is presented of a female newborn infant delivered with an Apgar Score of 1, who could not be resuscitated. There was a high arched palate, bell-shaped chest, contractures of writes inflexion, ankles and knees in extension, and intrauterine fractures. Clinical discussion led to a diagnosis of arthrogryposis secondary to fetal akinesia syndrome caused by nemaline myopathy. Pathology and pathologic discussion confirmed this diagnosis.

The spectrum of arthrogryposis in 33 chinese children.

The clinical profile of 33 children (19 boys, 14 girls) with multiple congenital contractures has been studied. The majority (54%) belong to arthrogryposis multiplex congenita with a static clinical course. Children were classified into three groups: group I (limb involvement only; n = 21) having arthrogryposis multiplex congenita (n = 18), distal arthrogryposis syndrome (n = 2) and Streeter syndrome (n = 1); group II (limb involvement with other malformation or anomalies; n = 7) having congenital contractural arachnodactyly (n = 3), Larsen syndrome (n = 1), multiple pterygium syndrome (n = 1), craniocarpotarsal dystrophy (n = 1), and Schwartz Jampel syndrome (n = 1); and group III (limb involvement with central nervous system dysfunction or mental retardation; n = 5) having myotonia dystrophica (n = 2), congenital muscular dystrophy (n = 1), foetal alcohol syndrome (n = 1) and Pena-Shokeir syndrome (n = 1). Three children died, one each of arthrogryposis multiplex congenita, congenital contractural arachnodactyly and myotonia dystrophica. The majority had a good prognosis with independent function and mobility.

A gene for a severe lethal form of X-linked arthrogryposis (X-linked infantile spinal muscular atrophy) maps to human chromosome Xp11.3-q11.2.

X-linked arthrogryposis Type I (X-linked infantile spinal muscular atrophy) is a rare disorder showing hypotonia, areflexia, and multiple congenital contractures (arthrogryposis) associated with loss of anterior horn cells and death in infancy. We have studied an X-linked arthrogryposis family using highly polymorphic microsatellite markers throughout the X chromosome. Meiotic breakpoint analysis (concordance analysis) based on shared regions of the founder X chromosome was successful in localizing the X-linked arthrogryposis gene to Xp11.3-q11.2. In this region, the highest two-point lod score was found with DXS991 (Zmax = 2.63, theta = 0.00). In multipoint linkage analysis covering the entire X chromosome, only the region defined by MAOB and DXS991 showed positive lod scores and all other regions showed negative lod scores. These data establish the first gene mapping assignment of an X-linked lethal form of human lower motor neuron disease.

Lethal arthrogryposis with anterior horn cell disease.

Fifteen infants (11 families) with lethal arthrogryposis and anterior horn motor neuron loss are described. The clinical presentation was the fetal akinesia deformation sequence (FADS) with multiple contractures and facial anomalies. At autopsy neurogenic muscular atrophy was present in all infants. The spinal cord showed a paucity of anterior horn motor neurons in the 12 infants studied. Both male and female infants were affected. Nine cases were sporadic, whereas in two families there were three affected cases. Consanguinity between the parents was reported in one family with one affected child. This and the recurrence of the condition speak for autosomal recessive inheritance. Detailed neuropathological examination and documentation of the clinical features are needed for a better delineation of and genetic counseling for perinatally lethal arthrogryposis.

Lethal congenital contracture syndrome: further delineation and genetic aspects.

In a national morphology based study of lethal arthrogryposis between 1979 and 1992, 40 fetuses and infants with lethal congenital contracture syndrome (LCCS, McKusick 253310) were found in Finland. The incidence of LCCS in Finland was 1:19,000 births. There were 20 affected males and 20 affected females in 26 families. In 16 cases the pregnancy was terminated after the prenatal diagnosis of total akinesia and fetal hydrops on ultrasound. There were 19 stillborn infants and five were born showing signs of life, but died within one hour. The segregation analyses yielded 0.45 affected by the "singles" method and 0.34 by the "sib" method. The birthplaces of the grandparents were located in the sparsely populated north east of Finland. This finding supports the existence of an autosomal recessive LCCS gene in Finland, particularly in the north eastern part.

Arthrogryposis multiplex congenita: an autopsy case of a fatal form.

A case of a severe and fatal form of arthrogryposis multiplex congenita with a full necropsy examination is presented in which the central nervous system and many muscles of the four extremities were examined histologically. The most striking feature was a great reduction in the muscular tissue of the limbs with a marked increase in the adipose tissue. The muscular changes were thought to be caused by neurogenic atrophy, and microscopy of the spinal cord revealed developmental abnormalities, including degenerative changes of the anterior horn cells. Neonatal and fatal cases of arthrogryposis multiplex congenita reported in the literature are briefly reviewed, and the characteristics of the present case and its relation to other congenital neuromuscular disorders are discussed.