Whole-exome sequencing identified two novel mutations of DYNC2LI1 in fetal skeletal ciliopathy.

BACKGROUND: Skeletal ciliopathies are a group of clinically and genetically heterogeneous disorders with the spectrum of severity spanning from relatively mild to prenatally lethal. The aim of our study was to identify pathogenic mutations in a Chinese family with two siblings presenting a Short-rib polydactyly syndrome (SRPS)-like phenotype. METHOD: Karyotyping and NGS-based CNVseq were performed. Obtaining the negative results in karyotyping and CNVseq, whole-exome sequencing (WES) using genomic DNA (gDNA) extracted from the umbilical cord blood of the first fetus was carried out, followed by bioinformation analysis. The candidate pathogenic variants were confirmed by Sanger sequencing in the family. RESULTS: No chromosomal abnormalities and pathogenic copy number variations (CNVs) were detected in the affected fetus with SRPS-like phenotype. WES analysis identified two novel compound heterozygous variants in DYNC2LI1, c.358G>T (p.Pro120Ser; NM_001193464), and c.928A>T (p.Lys310Ter; NM_ 001193464). Bioinformatics analysis suggested that c.358G>T (p.Pro120Ser) was likely pathogenic and c.928A>T (p.Lys310Ter) was pathogenic. Sanger sequencing of the two variants in family reveal that c.358G>T was from paternal origin and c.928A>T was from maternal origin, and the second affected fetus had the same compound heterozygous variants in DYNC2LI1. Definitive diagnosis of short-rib thoracic dysplasia 15 with polydactyly (SRTD15) was made in the family. CONCLUSION: Our results expand the mutational spectrum of DYNC2LI1 in severe skeletal ciliopathies. WES facilitates the accurate prenatal diagnosis of fetal skeletal ciliopathy, and provides helpful information for genetic counseling.

Majewski syndrome (short-rib polydactyly syndrome type II): Prenatal diagnosis and histological features of chondral growth plate, liver and kidneys.

The Majewski syndrome or short rib-polydactyly syndrome (SRPS) type II is a lethal skeletal dysplasia characterized by severe IUGR (intrauterine growth restriction) and dysmorphic face, polydactyly, relatively proportionate head size at birth with later progression to microcephaly. A case of second trimester ultrasound diagnosis of SRPS type II is reported with review of the medical record of previous observed cases. Postmortem examination and radiogram confirmed the clinical diagnosis. Histological examination of the femoral epypheseal chondral plate showed an expanded and irregular hypertrophic zone. Moreover, characteristic cortico-medullary cysts of both kidneys and portal fibrosis were also demonstrated; findings consistent with the broad phenotypic spectrum of this rare skeletal disease.

WDR34 mutations that cause short-rib polydactyly syndrome type III/severe asphyxiating thoracic dysplasia reveal a role for the NF-κB pathway in cilia.

Short-rib polydactyly (SRP) syndrome type III, or Verma-Naumoff syndrome, is an autosomal-recessive chondrodysplasia characterized by short ribs, a narrow thorax, short long bones, an abnormal acetabulum, and numerous extraskeletal malformations and is lethal in the perinatal period. Presently, mutations in two genes, IFT80 and DYNC2H1, have been identified as being responsible for SRP type III. Via homozygosity mapping in three affected siblings, a locus for the disease was identified on chromosome 9q34.11, and homozygosity for three missense mutations in WDR34 were found in three independent families, as well as compound heterozygosity for mutations in one family. WDR34 encodes a member of the WD repeat protein family with five WD40 domains, which acts as a TAK1-associated suppressor of the IL-1R/TLR3/TLR4-induced NF-κB activation pathway. We showed, through structural modeling, that two of the three mutations altered specific structural domains of WDR34. We found that primary cilia in WDR34 mutant fibroblasts were significantly shorter than normal and had a bulbous tip. This report expands on the pathogenesis of SRP type III and demonstrates that a regulator of the NF-κB activation pathway is involved in the pathogenesis of the skeletal ciliopathies.

An Ift80 mouse model of short rib polydactyly syndromes shows defects in hedgehog signalling without loss or malformation of cilia.

IFT80, a protein component of intraflagellar transport (IFT) complex B, is required for the formation, maintenance and functionality of cilia. Mutations in IFT80 cause Jeune asphyxiating thoracic dystrophy (JATD) and short rib polydactyly (SRP) type III. Both diseases are autosomal recessive chondrodysplasias and share clinical and radiological similarities, including shortening of the long bones and constriction of the thoracic cage. A murine Ift80 gene-trap line was used to investigate the role of Ift80 during development. The homozygote appears hypomorphic rather than a true null due to low level wild-type transcript production by alternative splicing around the gene-trap cassette. Hypomorphic levels of Ift80 result in embryonic lethality highlighting a key role for Ift80 in development. In rare cases, gene-trap homozygotes survive to postnatal stages and phenocopy both JATD and SRP type III by exhibiting growth retardation, shortening of the long bones, constriction of the ribcage and polydactyly. Mouse embryonic fibroblasts made from this line showed a significant reduction in hedgehog pathway activation in response to Hedgehog analog treatment. This defective signalling was not accompanied by the loss or malformation of cilia as seen in some knockout models of other IFT component genes. Phenotypes indicative of defects in cilia structure or function such as situs inversus, cystic renal disease and retinal degeneration were not observed in this line. These data suggest that there is an absolute requirement for Ift80 in hedgehog signalling, but low level expression permits ciliogenesis indicating separate but linked roles for this protein in formation and function.

Prenatal diagnosis of short-rib polydactyly syndrome type 3 (Verma-Naumoff type) by three-dimensional helical computed tomography.

We present a case of short-rib polydactyly syndrome (SRPs) type 3 in which accurate prenatal diagnosis was feasible using both ultrasonography and 3D-CT. SRP encompass a heterogeneous group of lethal skeletal dysplasias. However, the phenotypes overlap with those of nonlethal skeletal dysplasias (i.e. Ellis-van Creveld syndrome and Jeune syndrome). As accurate prenatal diagnosis of SRP is helpful for parents, we used 3D-CT in the early third trimester to examine a fetus suggested to have phenotypes of 'short-rib dysplasia group' on ultrasonography. 3D-CT showed mild modification of the vertebral bodies, small ilia with horizontal acetabula and triangular partial ossification defects, and subtle metaphyseal irregularities of the femora. These CT findings and an extensive literature search regarding the phenotypes of various diseases categorized as short-rib dysplasia group led to a correct prenatal diagnosis of SRP type 3. This case exemplified the usefulness of 3D-CT for the precise prenatal diagnosis of skeletal dysplasias.

Mutation in IFT80 in a fetus with the phenotype of Verma-Naumoff provides molecular evidence for Jeune-Verma-Naumoff dysplasia spectrum.

BACKGROUND: The lethal group of short-rib polydactyly (SRP) includes type I (Saldino-Noonan; MIM 263530), type II (Majewski; MIM 263520), type III (Verma-Naumoff; MIM 263510) and type IV (Beemer-Langer; MIM 269860). Jeune and Ellis-van Creveld dysplasias also used to be classified in the SRP group. Recently, mutations in a gene encoding a protein involved in intraflagellar transport, IFT80, have been identified in 3/39 patients with Jeune dysplasia but no extraskeletal manifestation. METHODS: Because of clinical and radiological similarities between Jeune dysplasia and the other lethal types of SRP, the authors decided to investigate IFT80 in a cohort of fetuses with the lethal forms of SRP (Majewski, Verma-Naumoff and Beemer-Langer) and antenatally diagnosed cases of Jeune dysplasia. Fifteen fetuses were identified. A double-molecular approach was adopted. For consanguineous families and for those with recurrent sibs, a haplotype analysis around the gene locus was first performed, and, for the others, all the coding exons of IFT80 were directly sequenced. RESULTS: Using the haplotype approach for two families, the authors excluded the IFT80 region as a candidate for them. Direct sequencing of IFT80 in the other 13 cases showed a G-to-C transversion in exon 8 (G241R) in only one SRP case closely related to the type III phenotype. CONCLUSIONS: The findings show that mutations in IFT80 can also be responsible for a lethal form of SRP and provide the molecular basis for the Jeune-Verma-Naumoff dysplasia spectrum.

Majewski osteodysplastic primordial dwarfism type II (MOPD II): expanding the vascular phenotype.

Majewski Osteodysplastic Primordial Dwarfism, Type II (MOPD II) is a rare, autosomal recessive disorder. Features include severe intrauterine growth retardation (IUGR), poor postnatal growth (adult stature approximately 100 cm), severe microcephaly, skeletal dysplasia, characteristic facial features, and normal or near normal intelligence. An Institutional Review Board (IRB) approved registry was created and currently follows 25 patients with a diagnosis of MOPD II. Based on previous studies, a neurovascular screening program was implemented and 13 (52%) of these patients have been found to have cerebral neurovascular abnormalities including moyamoya angiopathy and/or intracranial aneurysms. The typical moyamoya pathogenesis begins with vessel narrowing in the supraclinoid internal carotid artery, anterior cerebral (A1) or middle cerebral (M1) artery segments. The narrowing may predominate initially on one side, progresses to bilateral stenosis, with subsequent occlusion of the vessels and collateral formation. We present four patients who, on neurovascular screening, were found to have cerebrovascular changes. Two were asymptomatic, one presented with a severe headache and projectile vomiting related to a ruptured aneurysm, and one presented after an apparent decline in cognitive functioning. Analysis of the registry suggests screening for moyamoya disease be performed at the time of MOPD II diagnosis and at least every 12-18 months using MRA or computerized tomographic angiography (CTA). We believe this is imperative. If diagnosed early enough, re-vascularization and aneurysm treatment in skilled hands can be performed safely and prevent or minimize long-term sequelae in this population. Emergent evaluation is also needed when other neurologic or cardiac symptoms are present.

An unclassifiable short rib-polydactyly syndrome with acromesomelic hypomineralization and campomelia in siblings.

The short rib-polydactyly (SRP) group are lethal skeletal dysplasias with an autosomal recessive inheritance pattern that can be distinguished on radiological and histological grounds. We report on two consecutive pregnancies complicated by a SRP syndrome with acromesomelic hypomineralization and campomelia that cannot be definitely categorized, yet possesses features of this group of conditions. The skeletal changes observed in both cases included markedly shortened ribs, shortened humeri and femora, limb bowing, absent ossification of the radii, ulnae, tibiae and fibulae, as well as the bony elements of the hands and feet, hypoplastic scapulae and peritoneal calcifications. In one case, the pancreas was abnormal in shape, without a tail and the spleen was not identified. Ectopic splenic tissue and intestinal malrotation were identified and were suggestive of a laterality disorder. Whether these two cases should be considered an atypical form of SRP cannot be completely resolved at this present time and will need to wait on further progress in molecular testing.

Short rib-polydactyly syndrome: lethal chondrodysplasia associated with brain malformations in a 35-week-gestation infant.

This case report describes the neuropathological findings in an autopsy case of short rib-polydactyly syndrome (SRPS). The patient was a Japanese female neonate who was born at 35 weeks of gestation and died soon after birth due to severe cardiopulmonary insufficiency. Clinical and radiological findings were most consistent with SRPS type I (Saldino-Noonan type). General autopsy findings included situs inversus, persistent truncus arteriosus and endocardial cushion defect, hypoplastic lungs and adrenal glands, and vaginal atresia. Fixed brain weight was 330 g. Three different categories of pathological changes were detected in the brain. These were as follows: (1) multiple cyst formation in the parenchyma, (2) primary malformations of the nervous and mesenchymal tissues, and (3) deposition of an unusual substance in the cerebral white matter. The multiple cysts or cavities in the parenchyma may be due to severe hypoxic-ischemic insults related to the congenital heart anomaly. The primary malformations were summarized as follows: (1) capillary telangiectasia of the pia mater and choroid plexus, (2) olfactory dysplasia with asymmetry, (3) focal cortical dysplasia in the frontal lobe and cerebellum, (4) olivary dysplasia, and (5) enlargement of the posterior part of the lateral ventricle. Dysplastic changes of the nervous tissue can be classified into the group of neuronal migration disorders. Although biochemical properties of the unknown substance were not determined, it is considered to be some product derived from an inborn error of metabolism. Morphological data of SRPS is still scarce, and pathognomonic changes have not yet been elucidated. The present data suggests that coexistence of the nervous and mesenchymal malformations may be highly characteristic of SRPS.

Short rib-polydactyly syndrome.

INTRODUCTION: Short rib-polydactyly syndrome (SRPD) is an autosomal recessive, lethal skeletal dysplasia. It is characterized by short limb dwarfism, short ribs with thoracic hypoplasia, polydactyly, and multiple anomalies of major organs. CASE REPORT: We report a case of SRPD subtype II (Majewski) that was detected in the 36th week of gestation, showing hydropic change, narrow thorax, shortened limbs, protuberant abdomen, micromelia, polydactyly and extremely low set ears, depressed nasal bridge, and cleft palate. The family was informed of the fatal outcome of the condition. Delivery was induced, and the baby died just after the birth. DISCUSSION: Prenatal diagnosis is established with postmortem radiographic and pathologic examinations.

Majewski osteodysplastic primordial dwarfism type II (MOPD II): natural history and clinical findings.

A description of the clinical features of Majewski osteodysplastic primordial dwarfism type II (MOPD II) is presented based on 58 affected individuals (27 from the literature and 31 previously unreported cases). The remarkable features of MOPD II are: severe intrauterine growth retardation (IUGR), severe postnatal growth retardation; relatively proportionate head size at birth which progresses to true and disproportionate microcephaly; progressive disproportion of the short stature secondary to shortening of the distal and middle segments of the limbs; a progressive bony dysplasia with metaphyseal changes in the limbs; epiphyseal delay; progressive loose-jointedness with occasional dislocation or subluxation of the knees, radial heads, and hips; unusual facial features including a prominent nose, eyes which appear prominent in infancy and early childhood, ears which are proportionate, mildly dysplastic and usually missing the lobule; a high squeaky voice; abnormally, small, and often dysplastic or missing dentition; a pleasant, outgoing, sociable personality; and autosomal recessive inheritance. Far-sightedness, scoliosis, unusual pigmentation, and truncal obesity often develop with time. Some individuals seem to have increased susceptibility to infections. A number of affected individuals have developed dilation of the CNS arteries variously described as aneurysms and Moya Moya disease. These vascular changes can be life threatening, even in early years because of rupture, CNS hemorrhage, and strokes. There is variability between affected individuals even within the same family.

A 34-week-old male fetus with short rib polydactyly syndrome (SRPS) type I (Saldino-Noonan) with pancreatic cysts.

A 34-week-old male fetus (first diagnosed at 28 weeks of gestation) with short rib polydactyly type I Saldino-Noonan syndrome is presented in this study. In the postmortem examination of the fetus, pancreatic dysplasia, multiple cysts and multicystic dysplastic kidneys, omphalomesenteric cyst, ascites, malrotation, micropenis, undescended testes, bilateral inguinal hernia and hydrops were observed. The parents were first-degree cousins. One male and one female sibling had similar findings and both had died after birth. Only a four-year-old healthy daughter was alive. We believe these findings will be helpful in the differential diagnosis of further lethal skeletal dysplasia cases.

Short rib-polydactyly syndrome: a case report.

Short rib-polydactyly syndrome (SRPS) is a group of rare, lethal skeletal dysplasias characterized by short ribs and limbs, polydactyly, hypoplastic thorax and visceral anomalies. Our case had coarsening of facial features, low-set ears, lobulated tongue, cleft palate, and hypoplastic epiglottis. Short proximal parts of upper limbs, bilateral postaxial polydactyly of hands, and bifid big toe with zygodactyly were additional findings. Chest was narrow. Ambiguous genitalia was noted but testicles were in scrotum. Choroid plexus cyst and coarctation of aorta were found in autopsy. Radiographies of the skull revealed occipital horn accompanied by prominent external occipital protuberance. The thoracic cage was narrow and elongated with short and iliac wings, pubic and ischial rami were were hypoplastic, and both acetabula were shallow and trident shaped. All tubular bones had wide and rounded metaphyses. Because clinical and radiological features of the four established subtypes are very similar, there are difficulties in the classification. We report an infant whose radiological, clinical and postmortem features were consistent with type IV SRPS (Beemer-Langer).

Diagnostic dilemmas in the short rib-polydactyly syndrome group.

The short rib-polydactyly syndromes are a group of lethal skeletal dysplasias with autosomal recessive inheritance characterized by markedly short ribs, short limbs, usually polydactyly, and multiple anomalies of major organs. At least four types have been recognized. The radiological findings of 10 cases are presented. Each fetus or stillbirth has some of the radiological features of the four established types of short rib-polydactyly syndrome and raises diagnostic dilemmas in differentiating these entities. The overlapping phenotypes of these fetuses supports the previously suggested hypothesis that the different subtypes of the short rib-polydactyly syndrome group are not single entities, but rather part of a continuous spectrum with variable expressivity.

Short rib-polydactyly syndrome type III: comparison of ultrasound, radiology, and pathology findings.

Short rib-polydactyly syndrome (SRPS; types I-IV) is an autosomal recessive, lethal skeletal dysplasia characterized by short-limb dysplasia, narrow thorax, and polydactyly. This syndrome is invariable and can be detected by 2-trimester ultrasound. The underlying gene has not been discovered yet. We report a case of SRPS subtype III Verma-Naumoff-Le Marec that was sonographically detected at 20 weeks' gestation and compare prenatal ultrasound with postmortem findings from pathology and radiology. Since the risk of recurrence is 25%, early ultrasound for consecutive pregnancies was advised and performed at 11+6 weeks' gestation in the following pregnancy without any findings. Ultrasound diagnosis in this rare case of SRPS is a valuable tool for identification and early management, since there are no specific biochemical or histopathological markers for this syndrome. Radiological and pathological findings confirmed SRPS type III and assisted in the differential diagnosis of the subtype.

New case of Beemer-Langer syndrome.

We present the case of a male infant born at 37 weeks gestation with multiple congenital anomalies, including hydrops fetalis, facial and visceral abnormalities, short ribs, and short limbs without polydactyly. We believe that this represents a further case of the Beemer-Langer syndrome, a relatively recently described form of lethal osteochondrodysplasia with an autosomal recessive mode of inheritance. This case also showed some less frequently described anomalies, including arachnoid cysts of the brain and short intestines.

Short-rib-polydactyly syndrome type Verma-Naumoff-Le Marec in a fetus with histological hallmarks of type Saldino-Noonan but lacking internal organ abnormalities.

Up to seven short-rib-polydactyly (SRP) syndromes have been identified so far with marked clinical and pathological overlap. We describe a 32-week-old, nonhydropic male fetus with thoracic "dysplasia," short limbs, and unilateral postaxial polydactyly. All internal organs were normally developed, including the central nervous system. The external genitalia were unambiguously male, in accordance with a 46,XY karyotype. Radiological signs most closely resembled those of SRP, type Le Marec, though histology of the femoral physeal growth zone was consistent with the Saldino-Noonan type. The remarkable lack of visceral anomalies in conjunction with the radiological and histological findings further adds to the phenotypic spectrum of the SRP syndromes. The histological analysis in this case supports a close relationship between types Saldino-Noonan and Verma-Naumoff-Le Marec.

Short-rib polydactyly syndrome, Beemer-Langer type, with bilateral huge polycystic renal dysplasia: an autopsy case.

Short rib-polydactyly syndrome (SRPS) is a group of lethal skeletal dysplasia of an autosomal recessive inheritance characterized by markedly narrow ribs, micromelia, and multiple anomalies of major organs. We report a case of type IV SRPS with uncommon associations of polydactyly and bilateral polycystic kidneys, in a 28 week old female fetus. She was born dead to a 28 year old mother, showing a hydropic change, narrow thorax, and shortened limbs with postaxial heptasyndactyly of both hands and feet. Radiologic examination revealed short horizontal ribs, curved short tubular limb bones, small ilia and scapula, and a mild vertebral abnormality. Postmortem examination disclosed pulmonary hypoplasia, pancreatic cysts, hepatic fibrosis, and left persistent superior vena cava. In addition this case had bilateral huge polycystic renal dysplasia that was seldom described in any type of SRPS. Histologic sections of the vertebrae disclosed abnormal enchondral ossification with irregular and retarded hypertrophic zone.

Oral-facial-digital syndrome type IV (Mohr-Majewski syndrome): a fetopathological study.

We present a 22-week male fetus with cleft lip and palate, lobulated tongue, talipes equinovarus, and polysyndactyly. In addition there was skeletal dysplasia with micromelia and short ribs. Autopsy revealed a cardiac anomaly (perimembranous VSD), very incomplete lobation of the lungs, mild congenital hepatic fibrosis, and segmental renal cystic dysplasia. Brain anomalies included internal hydrocephalus, olfactory aplasia, and agenesis of the corpus callosum. This constellation of multiple congenital anomalies is consistent with the oral-facial-digital syndrome (OFDS) type IV. OFDS type IV may be a heterogeneous condition. Our pathological findings confirm that at least some of these cases a transitional phenotype between OFDS type II (Mohr syndrome) and short rib polydactyly syndrome type II (Majewski syndrome).

Craniotubular dysplasia with severe postnatal growth retardation, mental retardation, ectodermal dysplasia, and loose skin: Lenz-Majewski-like syndrome.

The heterogeneous group of craniotubular dysplasias is characterized by modeling errors of the craniofacial and tubular bones. Some conditions in this category cause not only skeletal abnormalities but also a variety of mesoectodermal dysplasias, as exemplified in Lenz-Majewski syndrome (MIM 151050), which comprises craniodiaphyseal dysplasia, failure to thrive, mental retardation, proximal symphalangism, enamel hypoplasia, and loose skin. We report on a boy with a hitherto unknown multisystem disorder, including skeletal changes that were regarded as a form of craniotubular dysplasia. The patient had a large head, exophthalmos, a broad nasal root, anteverted nostrils, large auricles, thick lips, micrognathia, severe postnatal growth retardation with emaciation, severe mental retardation, sparse hair growth, enamel hypoplasia, and thin, loose skin with hyperlaxity. Skeletal changes consisted of thickened calvaria, sclerosis of the skull base and facial bones, thick ribs, and metaphyseal undermodeling of the tubular bones. In addition, generalized osteopenia was evident. The present disorder overlaps phenotypically with Lenz-Majewski syndrome; nevertheless, the absence of diaphyseal hyperostosis and proximal symphalangism in the present patient was not consistent with Lenz-Majewski syndrome.