Autosomal Recessive Agammaglobulinemia Due to a Homozygous Mutation in PIK3R1.

The role of class IA phosphoinositide 3 kinases (PI3Ks) in immune function and regulation continues to expand with the identification of greater numbers of genetic variants. This case report is the second reported case of a homozygous premature stop codon within the PIK3R1 gene leading to autosomal recessive agammaglobulinemia. The proband, born to consanguineous parents, presented at 10 months of age with a history of oropharyngeal petechiae and bleeding from the mouth, gums, and tear ducts. Initial investigations revealed thrombocytopenia, neutropenia and the absence of B cells. Further genetic testing via a custom next-generation sequencing panel confirmed the presence of a homozygous mutation in PIK3R1, c.901 C>T, a premature stop codon at amino acid position 301. Given their many roles in immune regulation, recessive mutations in the PlK3R1 gene should be considered in infants presenting with hypogammaglobulinemia or agammaglobulinemia, particularly in the setting of parental consanguinity.

The effect of stem curvature on torsional stability of a generalized cemented joint replacement system.

PURPOSE: Implant loosening is a common complication that compromises the stability of joint replacement systems. Stem geometry is particularly influential in the stability of cemented implants, both before and after debonding occurs at the stem-cement interface. There are few studies assessing the effect of stem longitudinal curvature as a geometric factor in cemented implant stability. The purpose of this study was to compare the torsional stability of four generalized cemented implant stems (i.e., non-specific to joint), with varying degrees of longitudinal curvatures--zero, two, four, and six degrees. METHODS: Twelve specimens of each curvature angle were potted to a depth of 20 mm using bone cement, given 24 hours to cure, and then tested in a materials testing machine. Torque was applied to the stems under monotonic loading at a rate of 2.5 degrees/min, until five degrees of rotation had occurred. RESULTS: There were no differences in torsional stability among the four stem curvature angles, when the magnitudes of peak torque (P=.72; 1-ß = 0.13), rotation of the stem at peak torque (P=0.23; 1-ß = 0.38) and work required for five degrees of stem rotation (P=.58; 1-ß = 0.07) were compared. CONCLUSIONS: The findings from this study demonstrate that for short stems, stem curvature angles up to six degrees does not improve torsional stability when compared to the straight stem design.