Skeletal dysplasia
Gene: ALPL
Well established gene-disease association.
Clinical signs of the infantile form appear during the first 6 months of life and has high mortality, with 50% succumbing to respiratory failure due to undermineralization of the ribs. The childhood form in most cases presents after the first 6 months of life and before 5 years.
Adult HP presents during middle age, though the patient may have had mild rickets in childhood. Prognosis depends on clinical course and severity. Patients with adult or odonto-HP are believed to have a normal lifespan. AD/AR inheritance reported for these milder forms.
Treatment:
TNSALP ERT has received FDA approval in three settings: perinatal, infantile, and juvenile onset HP. However, the long-term effects of treatment are not fully known. In two prospective, single-arm studies, 68 individuals with severe, perinatal/infantile HP completed 24-weeks of ERT beginning at age 1 day – 78 months. Of patients requiring respiratory support (n = 26), 81% (n = 21) survived through the last date of assessment (median age 3.2 years) versus a 5% survival rate in historical controls. Further, 54 required mechanical ventilation and of these, 91% survived and 85% were ventilator free at last contact, in comparison to 27% overall survival and 25% ventilator free in 48 historical controls. Radiographs from 64 of these individuals indicated improvement on the Radiographic Global Impression of Change (RGI-C) scale (defined as “responders”) in 74% at last assessment, though comparative historical data does not exist. Eighteen individuals with perinatal/infantile HP experienced fractures during treatment; the effect of ERT on fractures remains unclear. In a prospective open-label, single arm study, 8 patients with juvenile HP completed at least 48 months of therapy and were compared to 32 historical controls. By the RGI-C rating of radiographs, all eight patients were deemed responders; two (6%) of the historical controls were rated responders. Gait also improved in patients treated with ERT, with a 6-minute walk test improving to the normal range in six of six patients assessed by month 48, from none at baseline. The data are at present are insufficient to assess the effect of ERT on fractures in juvenile HP. The long-term effects of treatment are not fully known.
Treatment with bisphosphonates, commonly used for rickets, may be detrimental.Created: 21 Sep 2022, 1:36 a.m. | Last Modified: 21 Sep 2022, 1:36 a.m.
Panel Version: 0.209
Mode of inheritance
BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Phenotypes
Hypophosphatasia, adult 146300 (AD, AR); Hypophosphatasia, childhood 241510 AR; Hypophosphatasia, infantile 241500 AR; Odontohypophosphatasia 146300 AD, AR
Publications
Inborn error of bone metabolism. Well-established gene-disease association (see OMIM entry).
Sources: NHS GMSCreated: 25 Jan 2021, 4:36 a.m.
Mode of inheritance
BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Phenotypes
Hypophosphatasia; disorder of bone metabolism
Publications
Variants in this GENE are reported as part of current diagnostic practice
Severe forms of hypophosphatasia (perinatal and infantile) are generally associated with autosomal recessive disease, while the milder forms of hypophosphatasia (childhood, adult and odonto) have been associated with both autosomal dominant and recessive disease (PMID: 19500388, 23688511). Loss of function and dominant negative have both been reported as mechanisms of disease for this gene (ClinVar, PMID: 19500388).Created: 13 May 2020, 1:50 a.m. | Last Modified: 13 May 2020, 1:50 a.m.
Panel Version: 0.2814
Mode of inheritance
BOTH monoallelic and biallelic (but BIALLELIC mutations cause a more SEVERE disease form), autosomal or pseudoautosomal
Phenotypes
Hypophosphatasia, adult 146300 (AD, AR); Hypophosphatasia, childhood 241510 AR; Hypophosphatasia, infantile 241500 AR; Odontohypophosphatasia 146300 AD, AR
Publications
Mode of pathogenicity
Other
Gene: alpl has been classified as Green List (High Evidence).
Phenotypes for gene: ALPL were changed from hypophosphatasia; Osteogenesis Imperfecta and Decreased Bone Density; skeletal dysplasias to Hypophosphatasia, adult 146300 (AD, AR); Hypophosphatasia, childhood 241510 AR; Hypophosphatasia, infantile 241500 AR; Odontohypophosphatasia 146300 AD, AR
Publications for gene: ALPL were set to
Tag treatable tag was added to gene: ALPL.
gene: ALPL was added gene: ALPL was added to Skeletal dysplasia. Sources: Emory Genetics Laboratory,NHS GMS,Expert Review Green Mode of inheritance for gene: ALPL was set to BOTH monoallelic and biallelic (but BIALLELIC mutations cause a more SEVERE disease form), autosomal or pseudoautosomal Phenotypes for gene: ALPL were set to hypophosphatasia; Osteogenesis Imperfecta and Decreased Bone Density; skeletal dysplasias