Nonimmune hydrops fetalis and congenital disorders of glycosylation: A systematic literature review.

Numerous etiologies may lead to nonimmune hydrops fetalis (NIHF) including congenital disorders of glycosylation (CDG). Recognition of CDG in NIHF is challenging. This study reviews prenatal and neonatal characteristics of CDG presenting with NIHF. A systematic literature search was performed. Thirteen articles met the inclusion criteria. Twenty-one cases with NIHF associated with a CDG were reported. There were 17 live births, three pregnancy terminations, and one fetal demise. Timing of CDG diagnosis was reported mostly postnatally (90%; 10/11). Postnatal genetic testing was reported in 18 patients; three patients were diagnosed by isoelectric focusing of serum transferrin that showed a type 1 pattern. The genes reported for CDG with NIHF for 15 distinct families include: PMM2 in 47% (7/15), ALG9 in 20% (3/15), ALG8 in 13% (2/15), ALG1 in 7% (1/15), MGAT2 in 7% (1/15), and COG6 7% (1/15). In our review, 81% (17/21) reported facial dysmorphism, 52% (11/21) reported CNS abnormalities, most commonly cerebellar atrophy (64%; 7/11), and 38% (8/21) reported cardiovascular abnormalities, most commonly hypertrophic cardiomyopathy (63%; 5/8). Among live births, 71% (12/17) infants died at a median age of 34 days (range 1-185). Thrombocytopenia was reported in 53% (9/17) patients. Of those who survived past the neonatal period, 80% (4/5) had significant reported developmental delays. CDG should be on the differential diagnosis of NIHF in the presence of cerebellar atrophy, hypertrophic cardiomyopathy, or thrombocytopenia. Our review highlights the poor prognosis in infants with NIHF due to CDG and demonstrates the importance of identifying these disorders prenatally to guide providers in their counseling with families regarding pregnancy management. SYNOPSIS: Poor prognosis in fetuses and infants with nonimmune hydrops fetalis due to congenital disorders of glycosylation highlights the importance of prenatal diagnosis of this disorder.

Cell origin, volume and arrangement are drivers of articular cartilage formation, morphogenesis and response to injury in mouse limbs.

Limb synovial joints are composed of distinct tissues, but it is unclear which progenitors produce those tissues and how articular cartilage acquires its functional postnatal organization characterized by chondrocyte columns, zone-specific cell volumes and anisotropic matrix. Using novel Gdf5CreERT2 (Gdf5-CE), Prg4-CE and Dkk3-CE mice mated to R26-Confetti or single-color reporters, we found that knee joint progenitors produced small non-migratory progenies and distinct local tissues over prenatal and postnatal time. Stereological imaging and quantification indicated that the columns present in juvenile-adult tibial articular cartilage consisted of non-daughter, partially overlapping lineage cells, likely reflecting cell rearrangement and stacking. Zone-specific increases in cell volume were major drivers of tissue thickening, while cell proliferation or death played minor roles. Second harmonic generation with 2-photon microscopy showed that the collagen matrix went from being isotropic and scattered at young stages to being anisotropic and aligned along the cell stacks in adults. Progenitor tracing at prenatal or juvenile stages showed that joint injury provoked a massive and rapid increase in synovial Prg4+ and CD44+/P75+ cells some of which filling the injury site, while neighboring chondrocytes appeared unresponsive. Our data indicate that local cell populations produce distinct joint tissues and that articular cartilage growth and zonal organization are mainly brought about by cell volume expansion and topographical cell rearrangement. Synovial Prg4+ lineage progenitors are exquisitely responsive to acute injury and may represent pioneers in joint tissue repair.

Osteophyte formation and matrix mineralization in a TMJ osteoarthritis mouse model are associated with ectopic hedgehog signaling.

The temporomandibular joint (TMJ) is a diarthrodial joint that relies on lubricants for frictionless movement and long-term function. It remains unclear what temporal and causal relationships may exist between compromised lubrication and onset and progression of TMJ disease. Here we report that Proteoglycan 4 (Prg4)-null TMJs exhibit irreversible osteoarthritis-like changes over time and are linked to formation of ectopic mineralized tissues and osteophytes in articular disc, mandibular condyle and glenoid fossa. In the presumptive layer of mutant glenoid fossa's articulating surface, numerous chondrogenic cells and/or chondrocytes emerged ectopically within the type I collagen-expressing cell population, underwent endochondral bone formation accompanied by enhanced Ihh expression, became entrapped into temporal bone mineralized matrix, and thereby elicited excessive chondroid bone formation. As the osteophytes grew, the roof of the glenoid fossa/eminence became significantly thicker and flatter, resulting in loss of its characteristic concave shape for accommodation of condyle and disc. Concurrently, the condyles became flatter and larger and exhibited ectopic bone along their neck, likely supporting the enlarged condylar heads. Articular discs lost their concave configuration, and ectopic cartilage developed and articulated with osteophytes. In glenoid fossa cells in culture, hedgehog signaling stimulated chondrocyte maturation and mineralization including alkaline phosphatase, while treatment with hedgehog inhibitor HhAntag prevented such maturation process. In sum, our data indicate that Prg4 is needed for TMJ integrity and long-term postnatal function. In its absence, progenitor cells near presumptive articular layer and disc undergo ectopic chondrogenesis and generate ectopic cartilage, possibly driven by aberrant activation of Hh signaling. The data suggest also that the Prg4-null mice represent a useful model to study TMJ osteoarthritis-like degeneration and clarify its pathogenesis.