Unexpected findings in cervical spine in spondylometaphyseal dysplasia Sutcliff type FN1-related.

The autosomal dominant spondylometaphyseal dysplasia Sutcliff type or corner fracture type FN1-related is characterized by a combination of metaphyseal irregularities simulating fractures ("corner fractures"), developmental coxa vara, and vertebral changes. It is linked to heterozygous mutations in FN1 and COL2A1. Vertebral changes as delayed vertebral ossification, ovoid vertebral bodies, anterior vertebral wedging, and platyspondyly have been observed in this condition, while odontoid abnormalities have not been reported. We report an odontoid anomaly in a girl with SMD-CF FN1-related showing the heterozygous variant c.505T>A; p.(Cys169Ser), presenting at 11.9 years of age with acute quadriparesis. Images showed spinal cord compression and injury associated with os odontoideum and C1-C2 instability. She required decompression and instrumented occipitocervical stabilization, suffering from residual paraparesis. This paper describes the first case of SMD-CF FN1-related accompanied by odontoid anomalies.

Whole-exome sequencing detects somatic mutations of IDH1 in metaphyseal chondromatosis with D-2-hydroxyglutaric aciduria (MC-HGA).

We used exome sequencing of blood DNA in four unrelated patients to identify the genetic basis of metaphyseal chondromatosis with urinary excretion of D-2-hydroxy-glutaric acid (MC-HGA), a rare entity comprising severe chondrodysplasia, organic aciduria, and variable cerebral involvement. No evidence for recessive mutations was found; instead, two patients showed mutations in IDH1 predicting p.R132H and p.R132S as apparent somatic mosaicism. Sanger sequencing confirmed the presence of the mutation in blood DNA in one patient, and in blood and saliva (but not in fibroblast) DNA in the other patient. Mutations at codon 132 of IDH1 change the enzymatic specificity of the cytoplasmic isocitrate dehydrogenase enzyme. They result in increased D-2-hydroxy-glutarate production, α-ketoglutarate depletion, activation of HIF-1α (a key regulator of chondrocyte proliferation at the growth plate), and reduction of N-acetyl-aspartyl-glutamate level in glial cells. Thus, somatic mutations in IDH1 may explain all features of MC-HGA, including sporadic occurrence, metaphyseal disorganization, and chondromatosis, urinary excretion of D-2-hydroxy-glutaric acid, and reduced cerebral myelinization.

Description of four patients with TRIP11 variants expand the clinical spectrum of odontochondroplasia (ODCD) and demonstrate the existence of common variants.

More than two decades since the first clinical and radiological description of odontochondroplasia (ODCD) was reported, biallelic loss of function variants in the Thyroid hormone receptor interactor 11 gene (TRIP11) were identified, the same gene implicated in the lethal disorder achondrogenesis (ACG1A). Here we report the clinical and radiological follow-up of four ODCD patients, including two siblings and an adult who interestingly has the mildest form observed to date. Four TRIP11 variants were detected, two previously unreported. Subsequently, we review the clinical and radiological findings of the 14 reported ODCD patients. The majority of ODCD patients are compound heterozygotes for TRIP11 variants, 12/14 have a null allele and a splice variant whilst one is homozygous for an in-frame splicing variant, with the splice variants resulting in residual GMAP activity and hypothesized to explain why they have ODCD and not ACG1A. However, adult patient 4 has two potentially null alleles and it remains unknown why she has very mild clinical features. The c.586C>T; p.(Gln196*) variant, previously shown by mRNA studies to result in p.Val105_Gln196del, is the most frequent variant, present in seven individuals from four families, three from different regions of the world, suggesting that it may be a variant hotspot. Another variant, c.2993_2994del; p.(Lys998Serfs*5), has been observed in two individuals with a possible common ancestor. In summary, although there are clinical and radiological characteristics common to all individuals, we demonstrate that the clinical spectrum of TRIP11-associated dysplasias is even more diverse than previously described and that common genetic variants may exist.

Hypomorphic mutations of TRIP11 cause odontochondrodysplasia.

Odontochondrodysplasia (ODCD) is an unresolved genetic disorder of skeletal and dental development. Here, we show that ODCD is caused by hypomorphic TRIP11 mutations, and we identify ODCD as the nonlethal counterpart to achondrogenesis 1A (ACG1A), the known null phenotype in humans. TRIP11 encodes Golgi-associated microtubule-binding protein 210 (GMAP-210), an essential tether protein of the Golgi apparatus that physically interacts with intraflagellar transport 20 (IFT20), a component of the ciliary intraflagellar transport complex B. This association and extraskeletal disease manifestations in ODCD point to a cilium-dependent pathogenesis. However, our functional studies in patient-derived primary cells clearly support a Golgi-based disease mechanism. In spite of reduced abundance, residual GMAP variants maintain partial Golgi integrity, normal global protein secretion, and subcellular distribution of IFT20 in ODCD. These functions are lost when GMAP-210 is completely abrogated in ACG1A. However, a similar defect in chondrocyte maturation is observed in both disorders, which produces a cellular achondrogenesis phenotype of different severity, ensuing from aberrant glycan processing and impaired extracellular matrix proteoglycan secretion by the Golgi apparatus.

Clinical, radiological, and auxological characteristics of patients with cleidocranial dysplasia followed in a pediatric referral hospital in Argentina. / Características clínicas, radiológicas y auxológicas de pacientes con displasia cleidocraneal seguidos en un hospital pediátrico de referencia en Argentina.

Cleidocranial dysplasia is an autosomal dominant skeletal dysplasia caused by mutations in the RUNX2 gene; its prevalence has been estimated at 1/1 000 000 newborn infants. This study presents 37 patients (22 girls) assessed between 1992 and 2016 at the Skeletal Dysplasias Multidisciplinary Clinics of Hospital Garrahan, Argentina. FINDINGS: 35% of positive family history; median age at the time of diagnosis: 2.61 years old; positive radiological findings in the skull and pubis: 95%; in the clavicles: 100%. Dental and hearing complications were common. Auxology: boys had a median height of -1.81 SD (-3.26 to 0.2) and girls had a median height of -1.36 SD (-4.28 to 1.36). Five out of 13 patients were short for parental height. Adult height (median): 162.8 cm in boys and 149.2 cm in girls. No evident alterations were observed in the sitting height/height ratio. One patient had true macrocephaly; 12 (32%), relative macrocephaly. Intrafamily variability was described in terms of height.

La displasia cleidocraneal es una displasia esquelética autosómica dominante causada por mutaciones en el gen RUNX2, con una prevalencia estimada de 1/1 000 000 de recién nacidos. Se presentan 37 pacientes (22 mujeres) evaluados entre 1992 y 2016 en las clínicas de displasias esqueléticas, Hospital Garrahan, Argentina. Hallazgos: 35% de antecedentes familiares positivos; edad mediana al momento del diagnóstico: 2,61 años; características radiológicas positivas en el cráneo y el pubis: 95%; en las clavículas: 100%. Las complicaciones dentales y auditivas fueron comunes. Auxología: mediana de estatura de -1,81 (-3,26-0,2) DE en los varones, -1,36 (-4,28-1,36) DE en las mujeres. Cinco de trece pacientes fueron bajos para la estatura parental. Estatura adulta (mediana): 162,8 cm y 149,2 cm en los varones y las mujeres. No fueron evidentes alteraciones en la proporción estatura sentada/estatura. Un paciente presentó macrocefalia real; 12 (32%), macrocefalia relativa. Se describe variabilidad intrafamiliar de estatura.

Características clínicas, radiológicas y auxológicas de pacientes con displasia cleidocraneal seguidos en un hospital pediátrico de referencia en Argentina / Clinical, radiological, and auxological characteristics of patients with cleidocranial dysplasia followed in a pediatric referral hospital in Argentina

La displasia cleidocraneal es una displasia esquelética autosómica dominante causada por mutaciones en el gen RUNX2, con una prevalencia estimada de 1/1 000 000 de recién nacidos. Se presentan 37 pacientes (22 mujeres) evaluados entre 1992 y 2016 en las clínicas de displasias esqueléticas, Hospital Garrahan, Argentina. Hallazgos: 35% de antecedentes familiares positivos; edad mediana al momento del diagnóstico: 2,61 años; características radiológicas positivas en el cráneo y el pubis: 95%; en las clavículas: 100%. Las complicaciones dentales y auditivas fueron comunes. Auxología: mediana de estatura de -1,81 (-3,26-0,2) DE en los varones, -1,36 (-4,28-1,36) DE en las mujeres. Cinco de trece pacientes fueron bajos para la estatura parental. Estatura adulta (mediana): 162,8 cm y 149,2 cm en los varones y las mujeres. No fueron evidentes alteraciones en la proporción estatura sentada/estatura. Un paciente presentó macrocefalia real; 12 (32%), macrocefalia relativa. Se describe variabilidad intrafamiliar de estatura.

Cleidocranial dysplasia is an autosomal dominant skeletal dysplasia caused by mutations in the RUNX2 gene; its prevalence has been estimated at 1/1 000 000 newborn infants. This study presents 37 patients (22 girls) assessed between 1992 and 2016 at the Skeletal Dysplasias Multidisciplinary Clinics of Hospital Garrahan, Argentina. Findings: 35% of positive family history; median age at the time of diagnosis: 2.61 years old; positive radiological findings in the skull and pubis: 95%; in the clavicles: 100%. Dental and hearing complications were common. Auxology: boys had a median height of -1.81 SD (-3.26 to 0.2) and girls had a median height of -1.36 SD (-4.28 to 1.36). Five out of 13 patients were short for parental height. Adult height (median): 162.8 cm in boys and 149.2 cm in girls. No evident alterations were observed in the sitting height/height ratio. One patient had true macrocephaly; 12 (32%), relative macrocephaly. Intrafamily variability was described in terms of height.