Short rib-dysplasia group (with/without polydactyly): report of a patient suggesting the existence of a continuous spectrum

Buccal Anomalies, Cephalometric Analysis and Genetic Study of Two Sisters with Orofaciodigital Syndrome Type I

Orofaciodigital syndromes have many clinical and cephalometric anomalies, including facial irregularities, oral cavity abnormalities, and malformations of fingers and toes. In this case of twin girls, buccal exploration, cephalometric examination, and genetic analysis were performed to diagnose Orofaciodigital I or Orofaciodigital II syndrome. Clinically, the twins had several dental and skeletal irregularities. Genetic analysis revealed a DNA segment abnormality corresponding to exon 3 and presence of nucleotide change, 243C>G, leading to the missense mutation H81Q. This causative mutation associated with the OFD1 gene has not been reported previously. Both patients were diagnosed as having Orofaciodigital I syndrome.

Compound heterozygous NEK1 variants in two siblings with oral-facial-digital syndrome type II (Mohr syndrome)

The oral-facial-digital (OFD) syndromes comprise a group of related disorders with a combination of oral, facial and digital anomalies. Variants in several ciliary genes have been associated with subtypes of OFD syndrome, yet in most OFD patients the underlying cause remains unknown. We investigated the molecular basis of disease in two brothers with OFD type II, Mohr syndrome, by performing single-nucleotide polymorphism (SNP)-array analysis on the brothers and their healthy parents to identify homozygous regions and candidate genes. Subsequently, we performed whole-exome sequencing (WES) on the family. Using WES, we identified compound heterozygous variants c.[464G>C];[1226G>A] in NIMA (Never in Mitosis Gene A)-Related Kinase 1 (NEK1). The novel variant c.464G>C disturbs normal splicing in an essential region of the kinase domain. The nonsense variant c.1226G>A, p.(Trp409*), results in nonsense-associated alternative splicing, removing the first coiled-coil domain of NEK1. Candidate variants were confirmed with Sanger sequencing and alternative splicing assessed with cDNA analysis. Immunocytochemistry was used to assess cilia number and length. Patient-derived fibroblasts showed severely reduced ciliation compared with control fibroblasts (18.0 vs 48.9%, P<0.0001), but showed no significant difference in cilia length. In conclusion, we identified compound heterozygous deleterious variants in NEK1 in two brothers with Mohr syndrome. Ciliation in patient fibroblasts is drastically reduced, consistent with a ciliary defect pathogenesis. Our results establish NEK1 variants involved in the etiology of a subset of patients with OFD syndrome type II and support the consideration of including (routine) NEK1 analysis in patients suspected of OFD.

Antenatal Diagnosis of Jeune Syndrome (Asphyxiating Thoracic Dysplasia) with Micromelia and Facial Dysmorphism on Second-Trimester Ultrasound

Background

Jeune syndrome is a rare congenital malformation with a reported incidence of 1 in 100,000–130,000 live births. Thoracic hypoplasia is the most striking abnormality of this disorder. Here we report a case of Jeune syndrome with marked thoracic hypoplasia, micromelia and facial dysmorphism, which was diagnosed on a second-trimester antenatal real-time three-dimensional ultrasound.

Case Report

A 24-year-old primigravida came for routine anomaly scan at 19 weeks of gestation. Transabdominal grey scale and real time 3D ultrasound (US) was done with GE Logiq P5 with curvilinear array transducers (4C and 4D3C-L). US findings were consistent with the diagnosis of Jeune syndrome (Asphyxiating thoracic dysplasia).

Conclusions

Jeune syndrome is an extremely rare congenital disorder with a spectrum of abnormalities of which thoracic hypoplasia is the most striking. It can be diagnosed on early antenatal US by its characteristic skeletal and morphological features which can guide further management of pregnancy in form of termination or preparation for surgical correction of the deformity.

Targeted next-generation sequencing identifies novel compound heterozygous mutations of DYNC2H1 in a fetus with short rib-polydactyly syndrome, type III

A 26-year-old woman with a past history of fetal skeletal dysplasia was referred to our institution at 24weeks of gestation following a routine sonographic diagnosis of short limbs in the fetus. A fetal ultrasound showed short limbs, a narrow thorax, short ribs with marginal spurs, and polydactyly. Conventional cytogenetics analysis of cultured amniocytes demonstrated that the fetal karyotype was normal. Using targeted exome sequencing of 226 known genes implicated in inherited skeletal dysplasia, we identified compound heterozygous mutations in the DYNC2H1 gene in the fetus with short rib-polydactyly syndrome, type III (SRPS III), c.1151 C>T(p.Ala384Val) and c.4351 C>T (p.Gln1451*), which were inherited from paternally and maternally, respectively. These variants were further confirmed using Sanger sequencing and have not been previously reported. To our knowledge, this is the first report of DYNC2H1 mutations causing SRPS III, in the Chinese population. Our findings expand the number of reported cases of this rare disease, and indicate that targeted next-generation sequencing (NGS) is an accurate, rapid, and cost-effective method in the genetic diagnosis of fetal skeletal dysplasia.

The many faces of oral-facial-digital syndrome

The oral-facial-digital (OFD) syndrome is a heterogeneous group of abnormalities that share anomalies of the oral cavity, face and digits of hands and feet. On the basis of other anomalies of brain, kidneys, limbs, eyes and other organs, at least 13 subgroups have been described. We here describe four unrelated patients with this syndrome, who have the typical facial, oral and digital anomalies and also anomalies of other organs and systems. Facial features, digital malformations, as well as the existence of additional malformations all of which can be classified into different subgroups. The report points out the difficulty in delineation of the subtypes of OFD syndrome because of the overlapping features between OFD subgroups.

Clinical insights gained from eight new cases and review of reported cases with Jeune syndrome (asphyxiating thoracic dystrophy)

Jeune syndrome, originally described as asphyxiating thoracic dystrophy by Jeune et al. [Jeune et al. (1955); Arch Fr Pediatr 12:886-891], is an autosomal recessive osteochondrodysplasia with characteristic skeletal abnormalities, and variable renal, hepatic, pancreatic, and retinal complications. We present eight patients, including two brothers with Jeune syndrome, and an extensive review of 118 cases in the published literature with the purposes of: (1) defining the clinical and radiological diagnostic criteria for Jeune syndrome; (2) comparing our cases to those in the literature meeting the documented clinical and radiological findings of Jeune syndrome, in order to: (3) provide an accurate clinical characterization of Jeune syndrome with frequency of associated complications and outcome data. In order to estimate the frequency of phenotypic abnormalities in Jeune syndrome as precisely as possible, we did not include reports in the literature with incomplete descriptions of the radiologic and clinical findings, nor those reports having additional findings overlapping with other syndromes. We found that the occurrence of renal, hepatic, and ophthalmologic complications is variable; does not correlate with severity of the skeletal phenotype; nor is it predictable even with the presence of a well-defined skeletal phenotype, as in this study. Based upon these cases with Jeune syndrome, renal and hepatic abnormalities occur in approximately 30% of cases, with renal failure occurring in 38% of those with kidney involvement. Eye abnormalities are reported in 15%, but it is unclear whether this represents under-ascertainment. There is a 1.2:1 ratio between living and deceased patients; a respiratory cause of death is most common, occurring almost exclusively in those less than 2 years of age, and a renal etiology accounts for all deaths between the ages of 3-10 years of age. There is a paucity of affected individuals reported in the literature greater than age 20 years, and a lack of longitudinal data to obtain accurate data on morbidity and mortality of Jeune syndrome at older ages. This study provides a well-defined group of patients with Jeune syndrome with delineation of the frequency of associated findings, which may form a basis for current and future genotype-phenotype studies.

Ciliary abnormalities due to defects in the retrograde transport protein DYNC2H1 in short-rib polydactyly syndrome

The short-rib polydactyly (SRP) syndromes are a heterogeneous group of perinatal lethal skeletal disorders with polydactyly and multisystem organ abnormalities. Homozygosity by descent mapping in a consanguineous SRP family identified a genomic region that contained DYNC2H1, a cytoplasmic dynein involved in retrograde transport in the cilium. Affected individuals in the family were homozygous for an exon 12 missense mutation that predicted the amino acid substitution R587C. Compound heterozygosity for one missense and one null mutation was identified in two additional nonconsanguineous SRP families. Cultured chondrocytes from affected individuals showed morphologically abnormal, shortened cilia. In addition, the chondrocytes showed abnormal cytoskeletal microtubule architecture, implicating an altered microtubule network as part of the disease process. These findings establish SRP as a cilia disorder and demonstrate that DYNC2H1 is essential for skeletogenesis and growth.

The skeletal dysplasias

The skeletal dysplasias are a large, heterogeneous group of genetic conditions characterized by abnormal development, growth and maintenance of the elements (bones) that comprise the human skeleton. Many result in disproportionate short stature. The classification of these disorders has evolved over the past 30 years from purely clinical-pathological descriptions to a nosology that now also reflects their underlying molecular aetiology. Accurate diagnosis of these disorders requires comprehensive documentation of the history, analysis of longitudinal growth patterns, rigorous clinical evaluation of the individual and family, complete radiographic survey and, when available, examination of chondro-osseous specimens. The specific genetic defects underlying many of these conditions have now been elucidated, allowing links to be established between phenotype and genotype. Management revolves around treatment to prevent or minimize medical complications, psychosocial support of patients and their families, education of the medical profession and wider community and modification of the environment where appropriate.

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.

Oral-facial-digital syndrome type II (Mohr syndrome): clinical and genetic manifestations

The oral-facial-digital syndromes (OFDS) represent a heterogenous group of disorders characterized by oral malformation, facial anomalies, and digital anomalies. Type II OFDS was reported by Mohr in 1941. Mohr syndrome is an autosomal recessive inherited disease characterized by median cleft lip, poly lobed tongue, absence of medial incisors, and polydactyly of hands and feet. Some other different expressive types of OFDS cases have been reported, and identified with 11 different clinical entities up to the present. Until now, only three cases of OFDS II in Japanese patients have been detected except for our patient. At this time, we observed a Japanese patient of Mohr syndrome with median cleft lip and tongue, hypertrophied frenula, absence of left medial incisor, and bilateral bifidity of great toe. Lip and tongue plasty was performed at 7 months after birth and toe plasty was done at 11 months with good results.

Short rib polydactyly syndrome type III: histopathogenesis of the skeletal phenotype

A morphological study of the skeletal system in a case of short rib polydactyly syndrome type III (SRPS-III) documented a "bajonet" deformity of the ribs for misalignment and overlap of cartilaginous and bony ends. This deformity resulted from a 'tandem' change in endochondral bone formation that is, arrested orthotopic cartilage maturation and etherotopic perichondral cartilage differentiation and ossification. At the cartilaginous end, cartilage maturation and vascular invasion were absent. At the bony end, longitudinal bone growth occurred by a perichondral ectopic growth plate. 'Miniature' versions of this 'tandem' change were also demonstrated in the long bones of the limbs and included focally arrested orthotopic cartilage maturation at the growth plates, perichondral cartilage differentiation, and ossification within cartilage canals. Our morphological study indicates that a generalized loss of syncrony in cartilage removal and osteogenic differentiation occurs in all growth plates, albeit with varied expressivity, and represents, at tissue level, the mechanism by which the SRPS-III skeletal phenotype develops.

Mesomelic campomelia, polydactyly and Dandy-Walker cyst in siblings

The present report describes two fetuses, one female and one male, with thus far undescribed skeletal malformations. The mother was a gravida 2, para 0. Both pregnancies were terminated in the second trimester because of multiple congenital anomalies diagnosed ultrasonographically resembling a short rib-polydactyly syndrome. Both fetuses were found to have postaxial hexadactyly of the hands and feet, marked bilateral campomelia of the forearm and shank bones, and a Dandy-Walker cyst. In addition, the fourth ventricle was dilated in the first sibling and the second sibling had an inverse intestinal malrotation. A literature search failed to reveal similar observations.

Skeletal anomalies

It is possible to identify many types of skeletal dysplasias and conditions involving limb deformities prenatally using ultrasound. It is likely that in the future, with the advancing technology and discoveries in molecular genetics, specific mutation analysis will become available for many of these conditions. This will make first trimester diagnosis an option in many cases. Because of the complex nature of many of these cases, it may be helpful to use a multidisciplinary approach involving a radiologist and a geneticist at times. In utero radiographs may help clarify a diagnosis. In lethal cases where a specific diagnosis has not been confirmed, it may be helpful postpartum to obtain an autopsy; photographs; complete body radiographs; karyotypic analysis; and specimens of bone, cartilage, and fetal blood for further analysis.

Recurrence of short rib polydactyly syndrome - a rare skeletal dysplasia

A case of short rib polydactyly syndrome type I-Saldino Noonan was diagnosed in three successive pregnancies from a non consanguineous couple. Short limbs, short ribs, polydactyly, with visceral anomalies were noted and confirmed on autopsy.

Jeune asphyxiating thoracic dystrophy and short-rib polydactyly type III (Verma-Naumoff) are variants of the same disorder

Jeune syndrome (JS) and short-rib polydactyly syndrome type III (SRP type III) are autosomal recessive disorders characterized by short ribs and polydactyly. They are distinguished from each other by the more severe radiological and histological bone findings as well as the occurrence of facial anomalies, ambiguous genitalia, and occasionally, cloacal abnormalities in SRP type III. We present a family in which two children have mild JS and one has SRP type III as evidence that JS and SRP type III are variants of the same disorder. The intrafamilial variability may reflect the effects of modifying loci on gene expression.

Short rib-polydactyly syndrome: more evidence of a continuous spectrum

We report a fetus with radiological features of the four established types of short rib-polydactyly syndrome (SRPS). The phenotype of this fetus supports the previously suggested hypothesis that the different subtypes of the short rib and polydactyly syndrome are not single entities, but rather, part of a continuous spectrum with variable expressivity.

Cardiac malformations in patients with oral-facial-skeletal syndromes: clinical similarities with heterotaxia

Oral-facial-skeletal (OFS) syndromes include short rib-polydactyly (SRP) and oral-facial-digital (OFD) syndromes. Congenital heart defect (CHD), mainly atrioventricular canal defect (AVCD), is a cardinal finding in the Ellis-van Creveld (EVC) syndrome, but it occurs only occasionally in other SRP and OFD syndromes. The cardiac characteristics of all patients with OFS syndromes evaluated at our hospital from January 1986 to April 1997 were analyzed and compared with published reports. Ten patients with EVC syndrome, one with McKusick-Kaufman syndrome, and one with OFD syndrome type II had AVCD. Eight patients (67%) had a common atrium, eight (67%) a persistent left superior vena cava (LSVC) draining into the left atrium because of an unroofed coronary sinus in five (42%), and left-sided obstructive lesions in three (25%). One patient with EVC syndrome had AVCD, common atrium, double outlet right ventricle, persistent LSVC associated with "asplenia syndrome," visceral heterotaxia, and right isomerism. The combination of CHDs found in the personal series of OFS syndromes suggests pathogenetic similarity with heterotaxia syndromes. Published results also corroborate the association between OFS syndromes and CHDs usually occurring in heterotaxia. Molecular studies could shed light on the genetic mechanisms implicated in the cause of the OFS and heterotaxia syndromes.

Neuropathologic findings in a case of OFDS type VI (Váradi syndrome)

Oral-facial-digital syndrome type VI (OFDS VI) or Váradi syndrome is a rare autosomal-recessive disorder distinguished from other oral-facial-digital syndromes by metacarpal abnormalities with central polydactyly and by cerebellar abnormalities. Histopathologic characterization of the cerebellar abnormalities has not been described previously. We describe the neuropathologic findings in a stillborn, 21-week estimated gestational age (EGA) male fetus diagnosed antenatally with signs of OFDS VI. Autopsy findings included: facial abnormalities, postaxial central polydactyly of the right hand, bilateral bifid toes, and absence of cerebellar vermis with hypoplasia of the hemispheric cortex. Microscopic analysis of the cerebellum demonstrated absence of the subpial granular cell layer and disruption or dysgenesis of the glial architecture. These histopathologic findings suggest that a primary neuronal or glial cell defect, rather than an associated Dandy-Walker malformation, may account for the cerebellar abnormalities in this form of oral-facial-digital syndrome.

Jeune syndrome with tongue lobulation and preaxial polydactyly, and Jeune syndrome with situs inversus and asplenia: compound heterozygosity Jeune-Mohr and Jeune-Ivemark?

We report on a male infant with internal hydrocephalus, absence of corpus callosum, papillomas and lobulation of the tongue, notches of the alveolar ridges, short ribs, dysplastic pelvis, hypospadias, short limbs with bowed long tubular bones and postaxial polydactyly of hands, and preaxial polydactyly in one foot. Radiologically this case shares manifestations with Jeune syndrome; the tongue lobulation and the preaxial polydactyly are similar to findings in Mohr syndrome, or short-rib polydactyly syndrome (SRPS), type Majewski. In addition, a female newborn presented with manifestations of Jeune and Ivemark syndromes. One explanation for this overlap may be compound heterozygosity for these syndromes.