An observational study in Ectonucleotide Pyrophosphatase/Phosphodiesterase 1 Deficiency and ATP-Binding Cassette Subfamily C Member 6 Deficiency, sponsored by Inozyme Pharma. Terminated at 14 sites in 9 countries. Per ClinicalTrials.gov, last updated 2026-10-01.
Sponsored by Inozyme Pharma (part of BioMarin Pharmaceutical) · Observational
The study was terminated by the sponsor prior to planned completion based on a review of the data across indications and overall program considerations. Study termination was not related to participant safety.
The purpose of this prospective registry is to characterize the natural history of ectonucleotide pyrophosphatase/phosphodiesterase1(ENPP1) Deficiency and the infantile-onset form of adenosine triphosphate (ATP) binding cassette transporter protein subfamily C member 6 (ABCC6) Deficiency longitudinally. The registry will prospectively gather information about the genetic, biochemical, physiological, anatomic, radiographic, and functional manifestations (including patient reported outcomes [PROs]) of each disease during routine, standard-of-care visits, with the aim of developing a comprehensive understanding of the burden of illness and progressive nature of the disease.
ENPP1 Deficiency is a rare, genetic disorder caused by inactivating mutations in the ENPP1 gene that encodes the ENPP1 enzyme. Infantile-onset ENPP1 Deficiency has a high mortality (approximately 50%) in the first 0 to 6 months of life, a result of downstream cardiopulmonary complications. Pediatric patients with ENPP1 Deficiency typically experience rickets, a condition also known as autosomal-recessive hypophosphatemic rickets type 2 (ARHR2), while adults experience osteomalacia (softened bones), and they can exhibit a range of signs and symptoms that include hearing loss, arterial calcification, and cardiac and/or neurological involvement.
Like ENPP1 Deficiency, infantile-onset ABCC6 Deficiency is a rare, genetic disorder caused by mutations in the ABCC6 gene. Infantile-onset of ABCC6 Deficiency resembles the acute infantile form of ENPP1 Deficiency. Pediatric patients with biallelic or monoallelic ABCC6 mutations can present with cerebrovascular disease.
This is an international, multicenter, prospective, non-interventional, observational registry of patients with biallelic variants in ENPP1, symptomatic patients with monoallelic ENPP1 variants and the infantile-onset form of ABCC6 Deficiency (\<18 years of age). The registry will include patients with ENPP1 Deficiency or infantile-onset of ABCC6 Deficiency independent of treatment regimen. Note: patients participating in an INZ-701 interventional clinical study are not eligible.
Registry participation will consist of a Screening Period and an Observational Period. During the Screening Period, both retrospective data (past medical history) and data available at the time of consent (baseline visit) will be collected. Data collected will include standard of care assessments, which may consist of any or all of the following: laboratory testing, radiographical assessment of calcification and vascular stenosis, bone mineralization, with addition of performance outcomes, patient-, caregiver-, and physician-reported outcomes, and healthcare utilization. During the Observational Period, participants will be assessed during their routine visits for changes in their disease and PROs and data will be added periodically to the database. There will be an opportunity for an optional blood draw to assess levels of inorganic pyrophosphate (PPi) at each routine visit.
Inozyme Pharma is the lead sponsor of 12 studies on the registry; none are open to participants now.
Of its 6 completed or terminated interventional studies of FDA-regulated products, 2 (33%) have results posted.
First submitted before Inozyme Pharma became part of BioMarin Pharmaceutical.
Counted across the registry records on this site, refreshed daily.
Evidence of biallelic ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) variants in ENPP1 Deficiency
or
Evidence of monoallelic ENPP1 variants and disease-related symptoms
or
Infantile onset with biallelic adenosine triphosphate (ATP) binding cassette transporter protein subfamily C member 6 (ABCC6) variants in participants aged \<18 years.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Individuals eligible to participate must meet all the following inclusion criteria:
One of the following genetic or clinical criteria
A confirmed prenatal or postnatal molecular genetic diagnosis of ENPP1 Deficiency with biallelic mutations (ie, homozygous or compound heterozygous) performed by a College of American Pathologists/Clinical Laboratory Improvement Amendments (CAP/CLIA) certified laboratory or regional equivalent
OR
i. ≥ 1 traumatic vertebral fracture
ii. ≥ 2 fractures as an adult (eg, long-bones, digits, vertebrae)
iii. Low bone mineral density (dual-energy X-ray absorptiometry [DXA] Z-score \<1.5) and \<55 years of age
iv. Bone or joint pain interfering with movement or daily activities
v. History of myocardial infarction (MI), unstable angina, (TIA) or low cardiac output before the age of 40 yrs.
vi. History of rickets or bone deformity
vii. Diagnosis of ossification of the posterior longitudinal ligament (OPLL)
viii. Other clinical symptoms, with approval by Inozyme
OR
c. A confirmed prenatal or postnatal molecular genetic diagnosis of ABCC6 Deficiency with biallelic mutations confirmed by a certified CAP/CLIA laboratory or regional equivalent, and \<18 years of age
Exclusion Criteria:
Individuals who meet the following exclusion criteria will not be eligible to participate:
Patients who are currently participating in an INZ-701 interventional clinical study, with the exception of expanded access programs and long-term safety follow-up studies
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
TIA (transient ischaemic attack)
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
No Intervention for this observational study
Characterization of the natural history of ENPP1 Deficiency and the infantile-onset form of ABCC6 Deficiency longitudinally
Assessments will be collected during each subject's routine visit. The assessments will be done per local standard of care.
Time frame: Annually up to 10 years
Assessment of Patient Functional changes through a validated Patient Reported Outcomes (PROs) tool
For each subject, patient function will be assessed using the appropriate Patient-Reported Outcomes Measurement Information System (PROMIS) questionnaires. These may include: PROMIS Cognitive Function, PROMIS Fatigue, PROMIS Pain Intensity, PROMIS Pain Interference and PROMIS Physical Function. Each questionnaire is scored on a 5-point Likert scale ranging from 1 (never) to 5 (always). High scores indicate more of the domain being measured (eg, more fatigue, more physical function). Raw scores are converted to T-Scores based on a mean of 50 and a standard deviation of 10, allowing comparison of the sample to the general population. Parent Proxy questionnaires will be used for children aged 5 to \<18 years
Time frame: Annually up to 10 years
Assessment of Health-Related Quality-of-Life (HRQoL) changes through validated Patient Reported Outcomes (PROs) tools
For each subject, HRQoL will be assessed using the following scales: age 5 to \<18 years: Pediatric QoL scales (Short Form \[SF\]-10, Caregiver Global Impression of Status/Severity \[CaGI-S\]); age ≥18 years: Adult QoL scales (Short Form \[SF\]-36, Patient Global Impression of Status/Severity \[PGI-S\]) The SF-10 is a 10-item caregiver-completed questionnaire for assessment of physical and psychosocial HRQoL in children. Each question has 5 options ranging from "Excellent" to "Poor". Higher scores are associated with better HRQoL. The SF-36 measures a broad spectrum of physical and mental health domains, including physical functioning, role limitations due to physical and emotional problems, bodily pain, general health perceptions, vitality, social functioning, and emotional well-being. The SF-36 generates scores ranging from 0-100 with higher scores associated with better HRQoL. The CaGI-S and PGI-S will be scored across a 7-point scale with lower scores associated with better HRQoL.
Time frame: Annually up to 10 years
Measurement of inorganic phosphate (PPi) levels in patients' venous blood
For each subject, QoL will be assessed using the following scales: global clinical impression of severity (GCI-S) and, short form 10 health survey for children and short form 36 health survey for adults short form 10 health survey for children and short form 36 health survey for adults
Time frame: Annually up to 10 years
Plan to share: Undecided
No publications or documents are linked to this record.
The study was terminated by the sponsor prior to planned completion based on a review of the data across indications and overall program considerations. Study termination was not related to participant safety.
The study was terminated by the sponsor prior to planned completion based on a review of the data across indications and overall program considerations. Study termination was not related to participant safety.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is terminated, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
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Arterial calcification of infancy