Metaphyseal dysplasia, Spahr type: a mimicker of rickets.
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SUBMITTER: Balasubramaniyan M
PROVIDER: S-EPMC6700560 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Spondylo-epi-metaphyseal dysplasia (SEMD) is a group of inherited skeletal diseases characterized by the anomalies in spine, epiphyses and metaphyses. SEMD is highly heterogeneous and >20 distinct entities have been identified. Here we describe a novel type of SEMD in two unrelated Turkish patients who presented with severe platyspondyly, kyphoscoliosis, pelvic distortion, constriction of the proximal femora and brachydactyly. Although these phenotypes overlap considerably with some known SEMDs, they had a novel causal gene, exostosin-like glycosyltransferase 3 (EXTL3), that encodes a glycosyltransferase involved in the synthesis of heparin and heparan sulfate. The EXTL3 mutation identified in the patients was a homozygous missense mutation (c.953C>T) that caused a substitution in a highly conserved amino acid (p.P318L). The enzyme activity of the mutant EXTL3 protein was significantly decreased compared to the wild-type protein. Both patients had spinal cord compression at the cranio-vertebral junction and multiple liver cysts since early infancy. One of the patients showed severe immunodeficiency, which is considered non-fortuitous association. Our findings would help define a novel type of SEMD caused by EXTL3 mutations.
| S-EPMC5537416 | biostudies-literature
Project description:IntroductionRickets is not an unusual diagnosis for pediatricians even currently in developed countries. Children typically present with leg bowing, enlargement of wrists, rachitic rosary (swelling of costochondral junctions) and/or waddling gait. But not every child with growth delay and enlarged metaphyses is diagnosed with rickets. Metaphyseal anadysplasia (MAD) is a disorder of variable severity with metaphyseal flaring and irregularities, without vertebral abnormalities. MAD is characterized by an early onset and a regressive course in late childhood without treatment, despite persistent short stature. Autosomal dominant or recessive variants in the matrix metalloproteinase 13 gene (MMP13) are responsible for these transient metaphyseal changes.Case presentationWe report a new pathogenic heterozygous variant in MMP13 (NM_002427.4: c.216G>C, p.Gln72His) in a toddler, initially thought to have rickets, and his father, with MAD phenotypes. Additionally, we review the seven reported MMP13 variants.ConclusionOne should keep a wide differential diagnosis in cases of suspected rickets, including skeletal dysplasias which might have a regressive course.
| S-EPMC8140414 | biostudies-literature
Project description: Not available
| S-EPMC4322291 | biostudies-literature
Project description:BackgroundMetaphyseal dysplasia without hypotrichosis (MDWH) is a rare form of chondrodysplasia with no extraskeletal manifestations. MDWH is caused by RMRP mutations, but it is differentiated from the allelic condition cartilage-hair hypoplasia (CHH), which in addition to chondrodysplasia is characterised by thin hair, immunodeficiency and increased risk of malignancy. The long-term outcome of MDWH remains unknown.ObjectiveWe diagnosed severe agranulocytosis in a subject with RMRP mutations and normal hair. Based on this observation, we hypothesised that MDWH may, similar to CHH, associate with immune deficiency and malignancy.MethodsWe collected clinical and laboratory data for a cohort of 80 patients with RMRP mutations followed for over 30 years and analysed outcome data for those with features consistent with MDWH.ResultsIn our cohort, we identified 10 patients with skeletal but no extraskeletal features during preschool age. Eight of these patients developed malignancy or clinically significant immunodeficiency during follow-up. Two of them died during chemotherapy for malignancy. At the time of the first extraskeletal manifestation, patients were school aged, 20, 43 and 50 years old. Laboratory signs of immunodeficiency (impaired lymphocyte proliferative responses) were demonstrated in four patients before the onset of symptoms. The patient outside this cohort, who had RMRP mutations, skeletal dysplasia, normal hair and severe agranulocytosis at 18 years of age, underwent haematopoietic stem cell transplantation.ConclusionsMDWH can present with severe late-onset extraskeletal manifestations and thus should be reclassified and managed as CHH.
| S-EPMC6929920 | biostudies-literature
Project description:Metaphyseal dysplasia with maxillary hypoplasia and brachydactyly (MDMHB) is an autosomal-dominant bone dysplasia characterized by metaphyseal flaring of long bones, enlargement of the medial halves of the clavicles, maxillary hypoplasia, variable brachydactyly, and dystrophic teeth. We performed genome-wide SNP genotyping in five affected and four unaffected members of an extended family with MDMHB. Analysis for copy-number variations revealed that a 105 kb duplication within RUNX2 segregated with the MDMHB phenotype in a region with maximum linkage. Real-time PCR for copy-number variation in genomic DNA in eight samples, as well as sequence analysis of fibroblast cDNA from one subject with MDMHB confirmed that affected family members were heterozygous for the presence of an intragenic duplication encompassing exons 3 to 5 of RUNX2. These three exons code for the Q/A domain and the functionally essential DNA-binding runt domain of RUNX2. Transfection studies with murine Runx2 cDNA showed that cellular levels of mutated RUNX2 were markedly higher than those of wild-type RUNX2, suggesting that the RUNX2 duplication found in individuals with MDMHB leads to a gain of function. Until now, only loss-of-function mutations have been detected in RUNX2; the present report associates an apparent gain-of-function alteration of RUNX2 function with a distinct rare disease.
| S-EPMC3567275 | biostudies-literature
Project description:Spondylo-megaepiphyseal-metaphyseal dysplasia (SMMD) is a rare skeletal dysplasia with only a few cases reported in the literature. Affected individuals have a disproportionate short stature with a short and stiff neck and trunk. The limbs appear relatively long and may show flexion contractures of the distal joints. The most remarkable radiographic features are the delayed and impaired ossification of the vertebral bodies as well as the presence of large epiphyseal ossification centers and wide growth plates in the long tubular bones. Numerous pseudoepiphyses of the short tubular bones in hands and feet are another remarkable feature of the disorder. Genome wide homozygosity mapping followed by a candidate gene approach resulted in the elucidation of the genetic cause in three new consanguineous families with SMMD. Each proband was homozygous for a different inactivating mutation in NKX3-2, a homeobox-containing gene located on chromosome 4p15.33. Striking similarities were found when comparing the vertebral ossification defects in SMMD patients with those observed in the Nkx3-2 null mice. Distinguishing features were the asplenia found in the mutant mice and the radiographic abnormalities in the limbs only observed in SMMD patients. The absence of the latter anomalies in the murine model may be due to the perinatal death of the affected animals. This study illustrates that NKX3-2 plays an important role in endochondral ossification of both the axial and appendicular skeleton in humans. In addition, it defines SMMD as yet another skeletal dysplasia with autosomal-recessive inheritance and a distinct phenotype.
| S-EPMC2790567 | biostudies-literature
Project description:BackgroundOsteosclerotic metaphyseal dysplasia (OSMD) is a unique form of osteopetrosis characterised by severe osteosclerosis localised to the bone ends. The mode of inheritance is autosomal recessive. Its genetic basis is not known.ObjectiveTo identify the disease gene for OSMD.Methods and resultsBy whole exome sequencing in a boy with OSMD, we identified a homozygous 7 bp deletion (c.5938_5944delGAGTGGT) in the LRRK1 gene. His skeletal phenotype recapitulated that seen in the Lrrk1-deficient mouse. The shared skeletal hallmarks included severe sclerosis in the undermodelled metaphyses and epiphyseal margins of the tubular bones, costal ends, vertebral endplates and margins of the flat bones. The deletion is predicted to result in an elongated LRRK1 protein (p.E1980Afs*66) that lacks a part of its WD40 domains. In vitro functional studies using osteoclasts from Lrrk1-deficient mice showed that the deletion was a loss of function mutation. Genetic analysis of LRRK1 in two unrelated patients with OSMD suggested that OSMD is a genetically heterogeneous condition.ConclusionsThis is the first study to identify the causative gene of OSMD. Our study provides evidence that LRRK1 plays a critical role in the regulation of bone mass in humans.
| S-EPMC5769692 | biostudies-literature
Project description:Background: Diaphyseal and metaphyseal modeling defects lead to severe changes in bone mass and shape, which are common features in osteoporosis that linked to non-vertebral fractures. Original mechanism of diaphyseal and metaphyseal modeling defects has proved elusive. Studying rare syndromes can elucidate mechanisms of common disorders and identify potential therapeutic targets. Methods: We evaluated a family pedigree with craniometadiaphyseal dysplasia (CRMDD, OMIM 269300), a genetic disorder that is characterized by cortical-bone thinning, limb deformity, and absent of normal metaphyseal flaring and diaphyseal constriction. Systemic radiographic examination and serum hormone test were made for this rare disease. One patient and her two normal parents were examined by means of whole-exome sequencing (WES) to identify the candidate pathogenic gene and rule out mucopolysaccharidosis and Prader-Willi Syndrome by means of Sanger sequencing. Results: There are several conspicuous radiographic characteristics: (1) bullet-shaped phalanges, (2) long and narrow pelvic inlet, absent of supra-acetabular constriction, (3) round rod-shaped long tubular bones, (4) prominent aiploic mastoid, (5) bending-shaped limb, genua varus and genu varum, and (6) congenital dislocation of elbow. Here, we did not find any wormian bones, and there are several typical clinical characteristics: (1) macrocephaly and wide jaw, (2) Avatar elf-shaped ears, pointed and protruding ears, (3) hypertrophy of limbs, (4) flat feet and giant hand phenomenon, (5) nail dystrophy, (6) limb deformity, (7) high-arched palate, (8) superficial hemangiomas, (9) tall stature, and intellectual disability. In this patient, we found biallelic frameshift deletion mutations in WRAP53, and those two mutations were transmitted from her parents respectively. Conclusions: We describe her clinical and radiological findings and presented a new subtype without wormian bones and with a tall stature. Our study showed that craniometadiaphyseal dysplasia was caused by a deficiency of WRAP53 with autosomal recessive inheritance.
| S-EPMC8416243 | biostudies-literature
Project description:The regulated expansion of chondrocytes within growth plates and joints ensures proper skeletal development through adulthood. Mutations in the transcription factor NKX3.2 underlie spondylo-megaepiphyseal-metaphyseal dysplasia (SMMD), which is characterized by skeletal defects including scoliosis, large epiphyses, wide growth plates and supernumerary distal limb joints. Whereas nkx3.2 knockdown zebrafish and mouse Nkx3.2 mutants display embryonic lethal jaw joint fusions and skeletal reductions, respectively, they lack the skeletal overgrowth seen in SMMD patients. Here, we report adult viable nkx3.2 mutant zebrafish displaying cartilage overgrowth in place of a missing jaw joint, as well as severe dysmorphologies of the facial skeleton, skullcap and spine. In contrast, cartilage overgrowth and scoliosis are absent in rare viable nkx3.2 knockdown animals that lack jaw joints, supporting post-embryonic roles for Nkx3.2. Single-cell RNA-sequencing and in vivo validation reveal increased proliferation and upregulation of stress-induced pathways, including prostaglandin synthases, in mutant chondrocytes. By generating a zebrafish model for the skeletal overgrowth defects of SMMD, we reveal post-embryonic roles for Nkx3.2 in dampening proliferation and buffering the stress response in joint-associated chondrocytes.
| S-EPMC7860120 | biostudies-literature
Project description:Metaphyseal dysplasia with maxillary hypoplasia and brachydactyly (MDMHB) is an autosomal-dominant skeletal dysplasia characterised by metaphyseal flaring of the long bones, enlargement of the medial halves of the clavicles, maxillary hypoplasia, brachydactyly, dental anomalies and mild osteoporosis. To date, only one large French Canadian family and a Finnish woman have been reported with the condition. In both, intragenic duplication encompassing exons 3-5 of the RUNX2 gene was identified. We describe a new, three-generation family with clinical features of MDMHB and an intragenic tandem duplication of RUNX2 exons 3-6. Dental problems were the primary presenting feature in all four affected individuals. We compare the features in our family to those previously reported in MDMHB, review the natural history of this condition and highlight the importance of considering an underlying skeletal dysplasia in patients presenting with significant dental problems and other suggestive features, including disproportionate short stature and/or digital anomalies.
| S-EPMC6117264 | biostudies-literature