Are Melnick-Needles syndrome and oto-palato-digital syndrome type II allelic? Observations in a four-generation kindred

A novel FLNA variant in a fetus with skeletal dysplasia

Otopalatodigital spectrum disorder (OPDSD) is characterized by variable phenotypes, including skeletal dysplasia, and is caused by pathogenic variants in filamin A-encoding FLNA. FLNA variants associated with lethal OPDSD primarily alter the CH2 subdomain of the ABD of FLNA. Herein, we report a novel FLNA mutation in a fetus with severe skeletal dysplasia in a pregnant multigravida female with a history of repeated miscarriages and terminations.

A family of Melnick-Needles syndrome: a case report

BACKGROUND

Melnick-Needles syndrome (MNS) is an extremely rare osteochondrodysplasia caused by a mutation of FLNA, the gene encoding filamin A. MNS is inherited in an X-linked dominant manner. In this study, we describe three members of the same family with MNS, who exhibited different phenotypic severity despite having an identical FLNA gene mutation.

CASE PRESENTATION

The patient was 16 months old, with a history of delayed physical development, multiple upper respiratory infections and otitis media episodes. She was referred to our orthopedic clinic because of bowed legs and an abnormal plain chest radiograph. Both upper and lower extremities were bowed. Plain X-rays showed thoracolumbar kyphoscoliosis, with anterior and posterior vertebral scalloping, and thin, wavy ribs. Hypoplasia of the pubis and ischium, with bilateral coxa valga, were also noted. Target exome sequencing revealed a heterozygous mutation of FLNA, c.3578 T > C, p.Lys1193Pro, which confirmed the diagnosis of MNS. Her older sister and mother had minimal deformities of the axial and extremity skeleton, but genetic analyses revealed the same FLNA mutation as the patient. The mutation identified in this family has not been previously reported.

CONCLUSION

This report illustrates the potential inherited nature of MNS and the phenotypic variability of clinicoradiologic characteristics. In patients with traits suggestive of MNS, a careful medical and family history should be obtained, and genetic testing should be performed for the patient, as well as all family members.

Clinical Experience of Treatment of Facial Malformations in Oto-Palato-Digital Syndrome: A Familial Patient

Oto-palato-digital syndrome type 1 (OPD1) is an X-linked recessive disorder comprising characteristic facial appearances and skeletal alterations. The authors report OPD1 in a mother and her 2 sons who had multiple common congenital anomalies. Both of the brothers were born with mild hearing impairment, frontal bossing with prominent supraorbital ridges, downslanting palpebral fissures, dental malocclusion, and palatal clefts. They underwent a series of aesthetic surgeries for their facial malformations with good cosmetic results. The mother had a milder phenotype with less prominent craniofacial defects that did not require surgical correction. The older brother required a 2-jaw surgery whereas the younger brother required a surgically assisted rapid palatal expansion. In the second series of operations, both brothers underwent scraping of their prominent supraorbital ridge. They have been free of complications throughout their 16-year follow-up. The authors also screened the family for possible genetic etiologies and identified mutations in the causative gene of OPD1 on Xq28 in all 3 patients. In conclusion, the authors have identified 3 patients with OPD1, performed surgical treatments on the affected brothers and have obtained good reconstructive results. There are no reports involving OPD1 patients who have received good surgical treatment. With careful examination and identification of patients with characteristic facies and skeletal abnormalities, it is our opinion that the authors can help more patients with this disease through surgical management.

Androgen receptor dysfunction as a prevalent manifestation in young male carriers of a FLNA gene mutation

Androgenic actions require the proper signal transmission by the androgen receptor (AR), a nuclear transcription factor. This is initially located in the cell cytoplasm and should translocates to the nucleus to interact with DNA. AR functional impairment causes diverse blockage degrees of androgenic steroid action, known as androgen insensitivity syndromes. Filamin A, a protein coded by the FLNA gene, is a co-activator of various cytoplasmic factors, including AR. The mutational inactivation of the FLNA gene induces insufficiency of translocation and activation of AR. Consequently, it causes a developmental disorder of the male gonad and hypogonadism, similar to those observed in partial androgen insensitivity. We report two brothers carrying a loss-of-function mutation of FNLA with gonadal differentiation disorder and hypospadias. Specific staining for AR shows almost an absolute absence of these receptors in the testicular tissue. This association recommends investigating a possible mutational inactivation of the FLNA gene in patients with cryptorchidism and epididymo-testicular dissociation. The study is especially indicated when the family history, more often that of the mother, is suggestive. Likewise, growth and gonadal development of all male patients carrying this genetic trait should be monitored since childhood.

Extended phenotypes in a boy and his mother with oto-palato-digital-syndrome type II

We describe additional phenotypic features in a boy and his mother. Both manifested the phenotypic/genotypic correlation of oto-palato-digital syndrome type II. The mother′s radiographs showed wormian bones of the skull, and paranasal bossing, her feet showed bilateral fusion of the cuboid with the lateral cuneiform bone with subsequent development of metatarsus varus associated with dysplastic distal phalanges.

Association of mutations in FLNA with craniosynostosis

Mutations of FLNA, an X-linked gene that encodes the cytoskeletal protein filamin A, cause diverse and distinct phenotypes including periventricular nodular heterotopia and otopalatodigital spectrum disorders (OPDS). Craniofacial abnormalities associated with OPDS include supraorbital hyperostosis, down-slanting palpebral fissures and micrognathia; craniosynostosis was previously described in association with FLNA mutations in two individual case reports. Here we present four further OPDS subjects who have pathological FLNA variants and craniosynostosis, supporting a causal link. Together with the previously reported patients, frontometaphyseal dysplasia was the most common clinical diagnosis (four of six cases overall); five patients had multiple suture synostosis with the sagittal suture being the most frequently involved (also five patients). No genotype-phenotype correlation was evident in the distribution of FLNA mutations. This report highlights the need to consider a filaminopathy in the differential diagnosis of craniosynostosis, especially in the presence of atypical cranial or skeletal features.

Correction of spine deformity in patients with Melnick-needles syndrome: report of 2 cases and literature review

BACKGROUND

Melnick-Needles syndrome (MNS) is a rare X-linked dominant disorder affecting the skeletal system and connective tissue. To date, < 70 cases with MNS have been documented. Although few reports in the literature have shown that these patients might develop kyphoscoliosis, there is no report regarding long-term follow-up of patients with MNS undergo spine surgery. The aim of this study is to describe 2 unique cases of MNS with long-term follow-up after instrumented posterior spinal fusion, multiple-level Ponte osteotomies, and pedicle subtraction osteotomies.

METHODS

A 17-year-old female patient (patient 1) was evaluated for the first time at our institution. She was diagnosed with MNS, severe kyphoscoliosis, and restrictive lung disease. After pulmonary function improvement, she underwent posterior spinal fusion. Halo-femoral traction with gradual weight increase was used a week before spinal surgery. Surgical correction of her spinal deformity was achieved through a hooks-and-wires construct. The second patient was an 18-year-old female (patient 2) who carried the diagnosis of MNS when she was first seen at our institution. She had a significant thoracolumbar junction kyphosis and gibbous. She also suffered from significant pulmonary disease with a stent in her right main stem bronchus. A posterior procedure consisting of multiple-level Ponte osteotomies and pedicle subtraction osteotomy at L2 was carried out.

RESULTS

Eight- and 5-year follow-up of patients 1 and 2, respectively, demonstrated solid fusion, a well-maintained correction, and no evidence of implant breakage.

CONCLUSIONS

The reported cases add to the literature of excellent long-term results of spinal deformity correction with instrumented posterior spinal fusion in patients with MNS. Patients with this condition should be closely monitored from early childhood for the development of spine deformity so that early referral to a spine surgeon can be made followed by appropriate treatment, if necessary.

Orthognathic surgery in Melnick-Needles-Syndrome. Case report and review of the literature

Melnick-Needles Syndrome (MNS) is a congenital syndrome associated with severe architectural disorder of the skeletal system that can cause significant effects on the craniofacial skeleton including poor aesthetics, impaired speech and masticatory problems. The authors report a case of a female patient who experienced masticatory constraint, hindered speech and functional problems related to a severe bite dysfunction due to the mandibular hypoplasia and the underlying bony architectural disorder associated with MNS. The patient underwent bilateral sagittal split osteotomy (BSSO) to correct her skeletal malocclusion and improve the characteristic aesthetics and speech. The inherent bony abnormalities with their altered collagen structure presented unique challenges to orthognathic surgery in this patient with an unpredictable bone healing process. In MNS patients a fragile trabecular bone structure and an increased bleeding tendency is thought to delay or forestall wound healing. The patient was treated successfully with BSSO and monocortical plate fixation following a well-established algorithm from orthodontic preparation to surgical protocol. A very satisfying outcome has been achieved, concerning functional rehabilitation and aesthetic improvement. A review of the literature revealed that little is known about bone regeneration and fracture healing in cases with MNS.

Mutational analysis of two boys with the severe perinatally lethal Melnick-Needles syndrome

Melnick-Needles syndrome (MNS) (OMIM 309350) is a rare, X-linked dominant condition, caused by mutations in the filamin A gene (FLNA, on Xq28). In females, the syndrome presents with bone dysplasia and characteristic facial changes. Affected males may show two different phenotypes. One is similar to the female phenotype and is seen in children born to unaffected mothers and suggesting new mutations. Alternatively, males born to affected mothers have an embryonic or perinatally lethal disorder. It has been claimed that MNS constitutes part of a spectrum including frontometaphyseal dysplasia, otopalatodigital syndrome type 1 (OPD1) and otopalatodigital syndrome type 2 (OPD2). These conditions are produced by different mutations in the filamin A gene (FLNA). MNS is caused by three different mutations in FLNA exon 22, to date detected only in females. We describe the clinical manifestations and present the results of FLNA exon 22 mutations screening in two boys with the perinatally lethal form of MNS and their affected mothers. In order to obtain DNA amplification from paraffin-embedded tissues, we designed a new method based on hemi-nested PCR. One of the children (and his mother) had a previously undescribed mutation produced by a double SNP in the positions 3776 and 3777 of the gene and leading to an amino acid substitution (NP_001447:p.[Gly1176Asp]). The second child (and his mother) had an already known mutation (NP_001447.2:p[.Ser1199Leu]). This is the first report confirming the presence FLNA mutations in boys with the perinatally lethal phenotype of MNS. (

Audiological outcomes after cochlear implantation in a patient with Melnick-Needles syndrome

This is the first report on a successful cochlear implantation in a patient suffering from the Melnick-Needles syndrome (MNS). This case study presents an MNS patient with peri-lingual profound hearing loss, implanted at the age of 38. MNS is a rare X-linked genetic bony dysplasia characterized by skeletal and facial abnormalities. Various soft tissue defects and hearing loss have also been described in MNS; however, this is the first report on bilateral inner ear malformation as a phenotypic feature of MNS. At 15 months after cochlear implantation there was 91% speech identification in open-set monosyllabic CVC test. In noise, the results obtained with the CVC lists were the following: 67% for SNR +15 dB, 52% for SNR +10 dB and 36% for SNR +5 dB. The patient is able to discriminate the differences in all 22 phoneme pairs in the APE phoneme discrimination test. This allows the patient to obtain significant communication ability through the telephone. Conclusions are as follows. 1) Bilateral inner ear malformations and bilateral profound perceptive hearing loss possibly belong to the phenotypic features of MNS. 2) Cochlear implant is potentially a good functional solution for patients suffering from MNS and profound hearing loss. 3) Exceptionally good results on auditory performance have been obtained in this MNS patient with peri-lingual profound hearing loss and almost 36 years duration of deafness.

A Japanese case of oto-palato-digital syndrome type II: an apparent lack of phenotype-genotype correlation

We report the case of a 12 year-old boy with oto-palato-digital syndrome type II (OPD II). He had various anomalies at birth, including bilateral cataracts, bilateral glaucoma, bilateral severe hearing impairment, congenital heart defect, umbilical herniation, bowed extremities and constrictions of various joints. These clinical features and whole body X-ray findings were compatible with OPD II. However, his ocular disorders such as congenital cataract and glaucoma, and congenital heart defect have never been associated with OPD II as far as we know. His chromosomal analysis revealed normal karyotype, 46,XY. Analysis of the filamin A gene using a standard PCR-direct sequencing method determined a C586T (Arg196Trp) missense mutation in exon 3. Interestingly, the same C586T mutation was reported previously in a patient with OPD I (mild form). Thus, phenotype-genotype correlation of OPD is lacking in those patients. Further clinical and genetic studies are needed to clarify the relationship between phenotypes and genotypes, or to identify other factor(s) that influence the clinical features of this syndrome.

Asphyxiating thoracic dystrophy with facial dysmorphism

Here it is reported a male newborn baby with features of asphyxiating thoracic dystrophy (ATD) with facial dysmorphism. The disproportionate rhizomelic short stature, narrow thorax, long fibulae, wide metaphysis and trident acetabule are consistent with diagnosis of ATD. In addition the baby had facial dysmorphism and broad thumbs and great toes similar to Oto-palato-digital syndrome type II (OPD II). The association of these features with ATD is not reported till date.

Otopalatodigital syndrome spectrum disorders: otopalatodigital syndrome types 1 and 2, frontometaphyseal dysplasia and Melnick-Needles syndrome

The term otopalatodigital syndrome spectrum disorders is an umbrella category that includes four phenotypically related conditions, otopalatodigital syndrome types 1 and 2, frontometaphyseal dysplasia and Melnick - Needles syndrome. The phenotype of these conditions in the male ranges from a severe perinatally lethal multiple malformation syndrome to a mild skeletal dysplasia. Most, but not all, instances of these conditions are associated by mutations in the X-linked gene encoding the cytoskeletal protein filamin A. Mutations in this gene are clustered, exhibit a strong genotype-phenotype correlation and are presumed to exert their effect by a gain-of-function mechanism.

Distraction in a case of otopalatodigital syndrome type II

INTRODUCTION

Otopalatodigital syndrome type II is a rare X-linked recessive disorder with generalized skeletal dysplasia and hearing anomalies. Its features include conductive hearing loss, unusual facies, cleft palate, micrognathia, and overlapping flexed fingers and toes. It is a more lethal variant of otopalatodigital syndrome type I. There are many consistently reported craniofacial and dental findings; however, no case has been published in dental literature.

CASE REPORT

We report a case of otopalatodigital syndrome type II with micrognathia, cleft of the soft palate, and partial anodontia, and discuss the combined orthodontic and surgical management.

CONCLUSION

We also discuss the differential diagnosis and consider more recent theories on possible aetiology as well as clinical management strategies for such cases.

Postzygotic mutation and germline mosaicism in the otopalatodigital syndrome spectrum disorders

The otopalatodigital syndrome (OPD) spectrum disorders are a heterogeneous group of skeletal dysplasias caused by mutations in the X-linked gene, FLNA. All OPD spectrum disorders (otopalatodigital syndromes types 1 and 2, frontometaphyseal dysplasia and Melnick-Needles syndrome) exhibit significant interfamilial variability in their expressivity, especially in female subjects. Factors contributing to this may include allelic heterogeneity, variation in the degree of skewing of X inactivation or, conceivably, mosaicism for the underlying causative mutation. We report here monozygotic twin sisters who are discordant for the severe phenotype, Melnick-Needles syndrome, associated with the heterozygous mutation, 3596C>T. We also describe two brothers with otopalatodigital syndrome type 1 due to the FLNA mutation 620G>A. The mutation is not detectable in the blood leucocytes of their clinically unaffected mother, indicating that she is a germline mosaic for the condition. The description of somatic mutations and germline mosaicism in FLNA has implications for clinical and molecular diagnosis, phenotypic expression and genetic counseling of families with these disorders.

A novel 9 bp deletion in the filamin a gene causes an otopalatodigital-spectrum disorder with a variable, intermediate phenotype

We report a four-generation pedigree with six affected females with cranial hyperostosis and various skeletal abnormalities. The phenotype is similar to frontometaphyseal dysplasia, which is part of the otopalatodigital (OPD) spectrum. We identified a novel in-frame deletion in exon 29 of the Filamin A gene (c.4904_4912del, p.R1635_V1637del) encoding rod domain repeat 14 of the protein. The disorder resulted in early lethality in male children. The phenotype of female individuals in this family is variable and rather mild, and bridges the phenotypes of various OPD-spectrum disorders.

A novel filamin A D203Y mutation in a female patient with otopalatodigital type 1 syndrome and extremely skewed X chromosome inactivation

Otopalatodigital syndrome type 1 (OPD1) [OMIM 311300] is an X-linked dominant multiple congenital anomalies disease mainly characterized by a generalized skeletal dysplasia, mild mental retardation, hearing loss, cleft palate, and typical facial anomalies. OPD1 belongs to a group of X-linked skeletal dysplasias known as oto-palato-digital syndrome spectrum disorders that also include OPD2, Melnick-Needles syndrome (MNS), and frontometaphyseal dysplasia (FMD). Recently, it has been demonstrated that mutations in the gene encoding the cytoskeletal protein Filamin A (FLNA) are responsible for this group of clinically overlapping human syndromes. We present the phenotypic and molecular data of a sporadic female patient clinically diagnosed with an OPD1 syndrome who carried a novel FLNA point mutation resulting in an Asp203Tyr substitution in the actin-binding domain of the protein. X-inactivation analyses demonstrated an extremely skewed pattern towards her maternal chromosome. Our results add to the molecular spectrum of the oto-palato-digital related syndromes and contribute to the delineation of phenotype-genotype correlation in this group of X-linked skeletal disorders.

Molecular pathology of filamin A: diverse phenotypes, many functions

Defective cell signalling during embryonic development is a well-recognized modus operandi of mutations in genes that lead to congenital malformations. This signalling occurs within and around a dynamic cellular cytoskeleton that is continuously under modulating influences during morphogenesis. Evidence is accumulating to suggest that filamin A, an actin-binding protein and the product of one of three paralogous filamin genes in humans, represents a key molecule that connects such signalling events to modulation of the cellular cytoskeletal architecture. This review summarizes the clinical consequences of mutations in the gene encoding filamin A, FLNA. The molecular pathology of this gene suggests remarkable functional pleiotropy, indicative of diverse roles in embryonic, fetal and postnatal development.

Localized mutations in the gene encoding the cytoskeletal protein filamin A cause diverse malformations in humans

Remodeling of the cytoskeleton is central to the modulation of cell shape and migration. Filamin A, encoded by the gene FLNA, is a widely expressed protein that regulates re-organization of the actin cytoskeleton by interacting with integrins, transmembrane receptor complexes and second messengers. We identified localized mutations in FLNA that conserve the reading frame and lead to a broad range of congenital malformations, affecting craniofacial structures, skeleton, brain, viscera and urogenital tract, in four X-linked human disorders: otopalatodigital syndrome types 1 (OPD1; OMIM 311300) and 2 (OPD2; OMIM 304120), frontometaphyseal dysplasia (FMD; OMIM 305620) and Melnick-Needles syndrome (MNS; OMIM 309350). Several mutations are recurrent, and all are clustered into four regions of the gene: the actin-binding domain and rod domain repeats 3, 10 and 14/15. Our findings contrast with previous observations that loss of function of FLNA is embryonic lethal in males but manifests in females as a localized neuronal migration disorder, called periventricular nodular heterotopia (PVNH; refs. 3-6). The patterns of mutation, X-chromosome inactivation and phenotypic manifestations in the newly described mutations indicate that they have gain-of-function effects, implicating filamin A in signaling pathways that mediate organogenesis in multiple systems during embryonic development.

Clinical and genetic heterogeneity in frontometaphyseal dysplasia: severe progressive scoliosis in two families

Frontometaphyseal dysplasia is a rare genetic syndrome affecting the skeletal system and connective tissue. It is believed to be inherited as an X-linked trait. Features of frontometaphyseal dysplasia overlap with other skeletal dysplasias. Prominent supraorbital ridges, radiologic evidence of cranial hyperostosis, and flared metaphyses are characteristic. Scoliosis, a rare associated finding, is usually mild, and familial progressive scoliosis has not been reported so far. The skeletal dysplasia and the associated clinical findings show significant intra- and interfamilial variability. The syndrome has been suggested to be an allelic variant of the Melnick-Needles osteodysplasty, an X-linked (dominant) entity. We present two families with frontometaphyseal dysplasia, in which both males and females showed the facial and skeletal features of the syndrome in association with progressive scoliosis. Some of the affected members also had hearing loss and urogenital anomalies, supporting the existence of the recently suggested entity "fronto-otopalatodigital-osteodysplasty syndome".

Phenotypic variation in Melnick-Needles syndrome is not reflected in X inactivation patterns from blood or buccal smear

Melnick-Needles syndrome is a rare putative X-linked dominant bone dysplasia. The patients have short stature, characteristic facial features, and a normal intelligence. The skeletal dysplasia includes S-shaped curvature of tubular bones and sclerosis of the base of the skull. The phenotype of affected individuals varies, even within families. This could be related to X chromosome inactivation. We report here on a very mildly affected mother and her two severely affected daughters with characteristic features of Melnick-Needles syndrome. In addition, the two daughters had very similar pigmented nevi on their back. X chromosome inactivation analysis of blood DNA revealed a skewed X inactivation pattern in all three affected females, with the normal X chromosome as the predominating active X chromosome. The X inactivation pattern was similar in buccal smear and blood DNA in the mother and one of the daughters, whereas the other daughter had a skewed pattern in blood only. X chromosome inactivation in blood and buccal smear DNA therefore does not explain the phenotypic variation in this family. The skewed X chromosome inactivation is in agreement with X-linked inheritance of Melnick-Needles syndrome and suggests a critical role of the Melnick-Needles gene in hematopoietic cell proliferation. Clinical evidence indicates that Melnick-Needles syndrome is allelic to the otopalatodigital syndromes, which have been assigned to Xq26-28. Haplotype analysis of the X chromosomes in this family was in agreement with the localization of the gene for Melnick-Needles syndrome to Xq25-qtel.

Linkage of otopalatodigital syndrome type 2 (OPD2) to distal Xq28: evidence for allelism with OPD1

Otopalatodigital syndrome type 1 (OPD1) is an X-linked semidominant condition characterized by malformations of the skeleton, auditory apparatus, and palate. Previous studies have established linkage to a 16-cM region of Xq27-q28. A proposed allelic variant of OPD1, termed "OPD2," is associated with a more severe, frequently lethal phenotype with visceral and brain anomalies in addition to skeletal, auditory, and palatal defects. We report linkage of the OPD2 phenotype to a 2-cM region of distal Xq28 in a Maori kindred, with a maximum multipoint LOD score of 3.31 between the markers DXS1073 and DXS1108. This provides support for allelism between OPD1 and OPD2 and reduces the size of the disease interval to 1.8-2.1 Mb. We also demonstrate that female carriers of this disorder exhibit skewed inactivation that segregates with the high-risk haplotype and may be inversely related to the severity with which they manifest features of the disorder.

Fronto-otopalatodigital osteodysplasia: clinical evidence for a single entity encompassing Melnick-Needles syndrome, otopalatodigital syndrome types 1 and 2, and frontometaphyseal dysplasia

Otopalatodigital syndrome type 2 is an X-linked disorder with minimal expression in carrier females and comprises typical facial anomalies and a generalized bone dysplasia with osteodysplastic changes, brachydactyly, and impaired survival. Recently several other severe malformations were reported in the condition. Melnick-Needles syndrome is an X-linked dominant disorder. Affected males are usually sporadic cases. The exceptional males born to symptomatic women present with a lethal disorder comprising generalized osteodysplasia, deficiency of the first ray, and facial anomalies strikingly similar to those of otopalatodigital syndrome type 2. We report here on three boys with classical, severe, and lethal otopalatodigital type 2 syndrome, and three boys with severe (lethal) Melnick-Needles syndrome, born to affected mothers. We suggest that otopalatodigital type 1 and 2, Melnick-Needles syndrome and frontometaphyseal dysplasia, sharing many clinical manifestations and a similar mode of inheritance, are variants of the same condition: fronto-otopalatodigital osteodysplasia. The relationships to similar syndromes (i.e., Saint-Martin-Gardner-Morrisson syndrome, serpentine fibula syndrome, atelosteogenesis type 3, boomerang dysplasia, and Yunis-Varon syndrome) are discussed.