Ptosis as a unique hallmark for autosomal recessive WNT1-associated osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a heritable connective tissue disorder, mainly characterized by bone fragility and low bone mass. Defects in the type I procollagen-encoding genes account for the majority of OI, but increasingly more rare autosomal recessive (AR) forms are being identified, which are caused by defects in genes involved in collagen metabolism, bone mineralization, or osteoblast differentiation. Bi-allelic mutations in WNT1 have been associated with a rare form of AR OI, characterized by severe osteoporosis, vertebral compression, scoliosis, fractures, short stature, and variable neurological problems. Heterozygous WNT1 mutations have been linked to autosomal dominant early-onset osteoporosis. In this study, we describe the clinical and molecular findings in 10 new patients with AR WNT1-related OI. Thorough revision of the clinical symptoms of these 10 novel patients and previously published AR WNT1 OI cases highlight ptosis as a unique hallmark in the diagnosis of this OI subtype

Osteoglophonic Dysplasia: Phenotypic and Radiological Clues

Osteoglophonic dysplasia (OD) is an extremely rare, skeletal dysplasia with an autosomal dominant mode of inheritance. Rhizomelic dwarfism, craniosynostosis, impacted teeth, hypodontia or anodontia, and multiple nonossifying bone lesions are the salient features of this condition. We report a 14-year-old girl with clinical and radiological features consistent with OD. She presented with disproportionate short stature, craniosynostosis, a prominent supraorbital ridge, delayed teeth eruption, hypodontia, and multiple nonossifying bone lesions in the femur, tibia, and fibula. She had hypophosphatemia, which is a known association in this dysplasia. She also had advanced bone age, which is an unreported feature of this dysplasia. This condition is caused by activating mutations in FGFR1 . A missense mutation was detected in the FGFR1 , NM_001174067 ( FGFR1 _v001):c.1115G > A [p.(Cys372Tyr)] confirming the diagnosis; this is the first mutation-proven case to be reported from India

Cortical atrophy and hypofibrinogenemia due to FGG and TBCD mutations in a single family: a case report

Abstract Background Blended phenotypes or co-occurrence of independent phenotypically distinct conditions are extremely rare and are due to coincidence of multiple pathogenic mutations, especially due to consanguinity. Hereditary fibrinogen deficiencies result from mutations in the genes FGA, FGB, and FGG, encoding the three different polypeptide chains that comprise fibrinogen. Neurodevelopmental abnormalities have not been associated with fibrinogen deficiencies. In this study, we report an unusual patient with a combination of two independently inherited genetic conditions; fibrinogen deficiency and early onset cortical atrophy. Case presentation The study describes a male child from consanguineous family presented with hypofibrinogenemia, diffuse cortical atrophy, microcephaly, hypertonia and axonal motor neuropathy. Through a combination of homozygosity mapping and exome sequencing, we identified bi-allelic pathogenic mutations in two genes: a homozygous novel truncating mutation in FGG (c.554del; p.Lys185Argfs*14) and a homozygous missense mutation in TBCD (c.1423G > A;p.Ala475Thr). Loss of function mutations in FGG have been associated with fibrinogen deficiency, while the c.1423G > A mutation in TBCD causes a novel syndrome of neurodegeneration and early onset encephalopathy. Conclusions Our study highlights the importance of homozygosity mapping and exome sequencing in molecular prenatal diagnosis, especially when multiple gene mutations are responsible for the phenotype

Eight years experience from a skeletal dysplasia referral center in a tertiary hospital in Southern India: a model for the diagnosis and treatment of rare diseases in a developing country

We report on a series of 514 consecutive diagnoses of skeletal dysplasia made over an 8-year period at a tertiary hospital in Kerala, India. The most common diagnostic groups were dysostosis multiplex group (n = 73) followed by FGFR3 (n = 49) and osteogenesis imperfecta and decreased bone density group (n = 41). Molecular confirmation was obtained in 109 cases. Clinical and radiographic evaluation was obtained in close diagnostic collaboration with expert groups abroad through Internet communication for difficult cases. This has allowed for targeted biochemical and molecular studies leading to the correct identification of rare or novel conditions, which has not only helped affected families by allowing for improved genetic counseling and prenatal diagnosis but also resulted in several scientific contributions. We conclude that (1) the spectrum of genetic bone disease in Kerala, India, is similar to that of other parts of the world, but recessive entities may be more frequent because of widespread consanguinity; (2) prenatal detection of skeletal dysplasias remains relatively rare because of limited access to expert prenatal ultrasound facilities; (3) because of the low accessibility to molecular tests, precise clinical-radiographic phenotyping remains the mainstay of diagnosis and counseling and of gatekeeping to efficient laboratory testing; (4) good phenotyping allows, a significant contribution to the recognition and characterization of novel entities. We suggest that the tight collaboration between a local reference center with dedicated personnel and expert diagnostic networks may be a proficient model to bring current diagnostics to developing countrie

Does the clinical phenotype of mucolipidosis-IIIγ differ from its αβ counterpart?: supporting facts in a cohort of 18 patients.

Mucolipidosis-IIIγ (ML-IIIγ) is a recessively inherited slowly progressive skeletal dysplasia caused by mutations in GNPTG. We report the genetic and clinical findings in the largest cohort with ML-IIIγ so far: 18 affected individuals from 12 families including 12 patients from India, five from Turkey, and one from the USA. With consanguinity confirmed in eight of 12 families, molecular characterization showed that all affected patients had homozygous pathogenic GNPTG genotypes, underscoring the rarity of the disorder. Unlike ML-IIIαβ, which present with a broader spectrum of severity, the ML-III γ phenotype is milder, with onset in early school age, but nonetheless thus far considered phenotypically not differentiable from ML-IIIαβ. Evaluation of this cohort has yielded phenotypic findings including hypertrophy of the forearms and restricted supination as clues for ML-IIIγ, facilitating an earlier correct choice of genotype screening. Early identification of this disorder may help in offering a timely intervention for the relief of carpal tunnel syndrome, monitoring and surgery for cardiac valve involvement, and evaluation of the need for joint replacement. As this condition may be confused with rheumatoid arthritis, confirmation of diagnosis will prevent inappropriate use of immunosuppressants and disease-modifying agents

Protein instability associated with AARS1 and MARS1 mutations causes trichothiodystrophy

Trichothiodystrophy (TTD) is a rare hereditary neurodevelopmental disorder defined by sulfur-deficient brittle hair and nails and scaly skin, but with otherwise remarkably variable clinical features. The photosensitive TTD (PS-TTD) forms exhibits in addition to progressive neuropathy and other features of segmental accelerated aging and is associated with impaired genome maintenance and transcription. New factors involved in various steps of gene expression have been identified for the different non-photosensitive forms of TTD (NPS-TTD), which do not appear to show features of premature aging. Here, we identify alanyl-tRNA synthetase 1 and methionyl-tRNA synthetase 1 variants as new gene defects that cause NPS-TTD. These variants result in the instability of the respective gene products alanyl- and methionyl-tRNA synthetase. These findings extend our previous observations that TTD mutations affect the stability of the corresponding proteins and emphasize this phenomenon as a common feature of TTD. Functional studies in skin fibroblasts from affected individuals demonstrate that these new variants also impact on the rate of tRNA charging, which is the first step in protein translation. The extension of reduced abundance of TTD factors to translation as well as transcription redefines TTD as a syndrome in which proteins involved in gene expression are unstable