TMEM263: a novel candidate gene implicated in human autosomal recessive severe lethal skeletal dysplasia

Introduction Skeletal dysplasia is a common, clinically and genetically heterogeneous disorder in the human population. An increasing number of different genes are being identified causing this disorder. We used whole exome sequencing (WES) for detection of skeletal dysplasia causing mutation in a fetus affected to severe lethal skeletal dysplasia. Patient Fetus was assessed by ultrasonography in second trimester of pregnancy. He suffers from severe rhizomelic dysplasia and also pathologic shortening of ribs. WES was applied to finding of causal mutation. Furthermore, bioinformatics analysis was performed to predict mutation impact. Results Whole exome sequencing (WES) identified a homozygous frameshift mutation in the TMEM263 gene in a fetus with severe lethal skeletal dysplasia. Mutations of this gene have been previously identified in dwarf chickens, but this is the first report of involvement of this gene in human skeletal dysplasia. This gene plays a key role in the growth hormone signaling pathway. Conclusion TMEM263 can be considered as a new gene responsible for skeletal dysplasia. Given the complications observed in the affected fetus, the mutation of this gene appears to produce much more intense complications than that found in chickens and is likely to play a more important role in bone development in human.

Thanatophoric Dysplasia

Background: The term tanatophorik comes from the Greek word thanatophorus which means "innate death" or "bearing death". The problem that underlies this disease is the process of bone formation. This disease is associated with an autosomal dominant inherited mutation of the fibroblast growth factor 3 receptor (FGFR3) gene on the arm of chromosome 4 (4p16.3). Because FGFR3 is the main modulator in bone formation, the typical clinical features of this disease include shortening of the extremities, curved femur, clover-like skull and narrowing of the thoracic cavity.Tanatophoric dysplasia is a skeletal disorder that is "lethal" or deadly. The deaths occurred due to respiratory failure caused by reduced chest cavity capacity, hypoplastic lungs and / or brainstem compression.Destination: Reported a case of thanatophoric dysplasiaMethod: Case Report Case Report: Case 33 years old woman, with preterm parturient G1P0A0H0 35-36 weeks 1 latent phase + history of 2x laparotomy + suspected fetal tanatophoric dysplasia. On ultrasound examination, it was found that BPD = 9.14 cm; AC = 30.56 cm; HC = 32.05 cm; FL = 2.55 cm; AFI; 9.06cm; SDAU = 1.72 cm. The presence of frontal bosing, saddle nose and micromilia (proximal, distal, phalanges) was found. The patient was planned for vaginal delivery and the progress of labor was followed. Patients provided informed consent regarding the possibility of fetal death during labor and after birth. During the active phase of the labor process, hypotony uterine innersia occurs and oxytocin drip is performed to accelerate labor. The baby was born male, weight 2175 grams, body length 34 cm and A / S: 1/0. Postmortem physical examination revealed macroscopic findings of tanatophoric dysplasia infants such as hypertelorism, low nasal bridge, cranio-facial disproportion. Narrow chest with protruding abdomen and short, bent limbs.Conclusion: Tanatophoric dysplasia is "lethal" skeletal dysplasia. Careful prenatal examination is required in diagnosis and termination of pregnancy. Keywords: Thanatophoric dysplasia, prenatal diagnosis

Case report: targeted whole exome sequencing enables the first prenatal diagnosis of the lethal skeletal dysplasia Osteocraniostenosis

Background Osteocraniostenosis (OCS) is a rare genetic disorder characterised by premature closure of cranial sutures, gracile bones and perinatal lethality. Previously, diagnosis has only been possible postnatally on clinical and radiological features. This study describes the first prenatal diagnosis of OCS. Case presentation In this case prenatal ultrasound images were suggestive of a serious but non-lethal skeletal dysplasia. Due to the uncertain prognosis the parents were offered Whole Exome Sequencing (WES), which identified a specific gene mutation in the FAMIIIa gene. This mutation had previously been detected in two cases and was lethal in both perinatally. This established the diagnosis, a clear prognosis and allowed informed parental choice regarding ongoing pregnancy management. Conclusions This case report supports the use of targeted WES prenatally to confirm the underlying cause and prognosis of sonographically suspected abnormalities.

Thanatophoric Dysplasia

Objective: Report a case of thanatophoric dysplasiaMethod: Case report Result: Case of a 25-year-old woman, with a diagnosis of gravid preterm G4P2A1H2 31-32 weeks + polyhydramnios + fetal hydrops, a single intrauterine live fetus with thanatophoric dysplasia. On ultrasound examination found fetal biometry; BPD: 7.78 cm, FL: 3.58 cm, HL: 3.11 cm, AC: 30.90 cm, HC: 28.48 cm AFI: 33.27 cm, a frontal bossing (+) picture appears, claver leaf skull (+) and micromelia (proximal, distal, phalanges). The ultrasound examination suggested Severe skeletal dysplasia (thanatophoric dysplasia), polyhydramnios, + single intrauterine live fetus + SC 1x scars. Then an amnioinfusion is performed and results are obtained. Chromosome analysis is carried out using the G-banding technique. Chromosomes have been studied from 20 cells from 3 different cell culture preparations and obtained the number of chromosomes in each cell studied is 46, XY which means the number of chromosomes 46 pieces with fetal sex chromosome XY. Mosaic chromosome abnormalities generally occur due to non-disjuntion in the mitotic phase after conception. At 33-34 weeks gestation, an infant was born by SC with birth weight: 1900 g, baby’s length: 31 cm, A / S 2/3.Conclusion : Thanatophoric dysplasia is a "lethal" skeletal dysplasia. A careful prenatal examination is needed in the diagnosis and termination of pregnancy.Keywords: Thanatophoric dysplasia, prenatal diagnosis

Achondrogenesis type 2 in a newborn with a novel mutation on the COL2A1 gene

Achondrogenesis is a group of rare and fatal disorders occurring in approximately one in every 40,000-60,000 newborns. Achondrogenesis is classified in three groups, as Achondrogenesis type 1A (Houston-Harris type or AC-G1A), Achondrogenesis type 1B (Parenti-Fraccaro type or ACG1B) and Achondrogenesis type 2 (Langer-Saldino type or ACG2), depending on clinical and radiological findings. Achondrogenesis Type 2 is a lethal skeletal dysplasia that is typically characterized by short arms and legs, a small chest with short ribs, lung hypoplasia, a prominent forehead, a small chin, and an enlarged abdomen that may accompanied by polydramnios and hydrops. This study contributes to the literature by presenting a patient who was admitted to the Level ΙΙΙ Neonatal Intensive Care Unit (NICU), Bursa, Turkey), with extremely short extremities, a small chest, abdominal distention and respiratory distress, who was diagnosed with ACG2. On the COL2A1 gene, genetic analysis with next generation sequencing (NGS), was revealed to have a heterozygous missense variation, c.2546G>A, p.Gly849Asp mutation, which is a different genetic variant that has not been previously described in the literature.

Thanatophoric dysplasia: a case report

Thanatophoric Dysplasia (TD) is a congenital, sporadic and most lethal skeletal dysplasia caused by new mutation in FGFR3 gene. Authors report such a rare case of a term alive baby with dysmorphic features, born to an unbooked, 40 years old G4P3+0 with non-consanguineous marriage; admitted at 9 months of gestation to present hospital with complain of pain abdomen for 2 days. Patient delivered a term female baby of vaginally which had delayed cry after birth, Admitted in NICU immediately with respiratory distress. The baby looked dysmorphic and suggested TD as most likely diagnosis. The case is being reported for its rarity and for high importance of early booking and anomaly scan. Early diagnosis is important since it provides alternative options of termination of pregnancy when an affected foetus is detected.