Characterization of tracheobronchomalacia in infants with hypophosphatasia

Efficacy and safety of asfotase alfa in patients with hypophosphatasia: A systematic review

BACKGROUND

Hypophosphatasia (HPP) is a rare genetic disorder characterized by defective bone mineralization, leading to skeletal abnormalities and systemic complications. Asfotase alfa, a recombinant human tissue-nonspecific alkaline phosphatase (TNSALP) enzyme replacement therapy, has emerged as a promising treatment for HPP. However, a comprehensive evaluation of its efficacy and safety is warranted to guide clinical practice effectively.

METHODS

The study followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was registered in Prospective Register of Systematic Reviews (PROSPERO). A search strategy across databases found studies on asfotase alfa for HPP. Two researchers independently extracted and assessed data. This systematic review examined how the drug impacted clinical outcomes such as survival rates, musculoskeletal symptoms, respiratory function, growth measurements, dental health, quality of life, and laboratory results.

RESULTS

This systematic review included 15 articles with a total of 455 HPP patients. Asfotase alfa was predominantly administered at a dose of 6 mg per kg per week among the reviewed studies. Notable findings included enhanced survival rates, relief from musculoskeletal pain, improvements in respiratory outcomes, growth parameters, dental health, and quality of life. Changes in laboratory variables indicated positive responses to treatment, including changes such as increase in alkaline phosphatase (ALP), decline in pyridoxal 5'-phosphate (PLP) and inorganic pyrophosphate (PPi) levels.

CONCLUSION

Asfotase alfa demonstrates efficacy in improving clinical outcomes and safety in patients with HPP. Its therapeutic benefits extend across various domains. However, Larger, age-stratified comparative studies are needed to further investigate the drug's effects in HPP patients.

Characterization of Genetic Variants of Uncertain Significance for the ALPL Gene in Patients With Adult Hypophosphatasia

Hypophosphatasia (HPP) a rare disease caused by mutations in the ALPL gene encoding for the tissue-nonspecific alkaline phosphatase protein (TNSALP), has been identified as a potentially under-diagnosed condition worldwide which may have higher prevalence than currently established. This is largely due to the overlapping of its symptomatology with that of other more frequent pathologies. Although HPP is usually associated with deficient bone mineralization, the high genetic variability of ALPL results in high clinical heterogeneity, which makes it difficult to establish a specific HPP symptomatology. In the present study, three variants of ALPL gene with uncertain significance and no previously described (p.Del Glu23_Lys24, p.Pro292Leu and p.His379Asn) were identified in heterozygosis in patients diagnosed with HPP. These variants were characterized at phenotypic, functional and structural levels. All genetic variants showed significantly lower in vitro ALP activity than the wild-type (WT) genotype (p-value <0.001). Structurally, p.His379Asn variant resulted in the loss of two Zn²⁺ binding sites in the protein dimer which may greatly affect ALP activity. In summary, we identified three novel ALPL gene mutations associated with adult HPP. The correct identification and characterization of new variants and the subsequent study of their phenotype will allow the establishment of genotype-phenotype relationships that facilitate the management of the disease as well as making it possible to individualize treatment for each specific patient. This would allow the therapeutic approach to HPP to be personalized according to the unique genetic characteristics and clinical manifestations of each patient.