Biotinidase Deficiency

Guidance for primary care clinicians receiving a positive newborn screen result

Other Names

Multiple carboxylase deficiency, late-onset

ICD-10 Coding

D81.810, Biotinidase deficiency

Disorder Category

Organic acidemia

Screening

Abnormal Finding

Decreased activity of biotinidase, an enzyme that releases biotin (vitamin H) from proteins

Tested By

Colorimetric, semiquantitative enzyme assay; false positives may occur in premature infants and in samples placed in plastic before sufficient drying or exposed to excessive heat

Description

Biotinidase is an inherited disorder in which the body is unable to reuse and recycle biotin, a B vitamin found in foods such as liver, egg yolks, and milk. The BTD gene is responsible for making biotinidase, which, in turn, is responsible for extraction of biotin from ingested dietary sources and recycling of biotin from endogenous sources (breakdown of endogenous proteins). Biotin is an essential cofactor for several carboxylase enzymes required to process proteins, fats, or carbohydrates. The developing brain is particularly sensitive to biotin deficiency. Patients usually appear perfectly normal at birth but can develop irreversible hearing and vision loss if untreated.

Clinical Characteristics

With treatment of biotinidase deficiency, clinical outcomes are excellent.

Without treatment, outcomes depend on the inherent severity of disease. In the severe form with profound biotinidase deficiency (enzyme activity <10% of normal), neurologic injury, hearing loss, blindness, and death may result. Symptoms may develop as soon as the first week of life or as late as 10 years of age (mean age of 3 1/2 months).

Initial signs/symptoms of biotinidase deficiency may include:
  • Seizures
  • Hypotonia
  • Hyperventilation, laryngeal stridor, and/or apnea
  • Eczematoid rash
  • Alopecia
  • Conjunctivitis
  • Candidiasis
  • Ataxia
Older children may manifest:
  • Paresis
  • Developmental delay
  • Neurosensory hearing loss
  • Optic atrophy and scotomata
  • Recurrent viral and fungal infections
Children with untreated partial biotinidase deficiency may manifest any of the above symptoms, though generally they will be mild and occur only with concomitant stressors, such as prolonged infection.

Incidence

The prevalence of biotinidase deficiency is 1:60,000 overall; 1 :130,000 for profound deficiency and 1:110,00 for partial deficiency; carrier (heterozygous for BTD mutation) frequency is about 1:120.

Inheritance

Autosomal recessive

Primary Care Management

Next Steps After a Positive Screen

  • Contact the family and evaluate the infant for poor feeding, lethargy, or hypotonia.
  • Provide emergency treatment/referral if symptoms are present.

Confirming the Diagnosis

  • To confirm the diagnosis of biotinidase deficiency, work with Newborn Screening Services (see RI providers [2]).
  • Follow-up testing will include quantitative enzyme assay on serum/plasma... A panel of 5 common BTD mutations detects approximately 60% of disease-causing mutations and can identify a specific mutation responsible for partial biotinidase deficiency (p.D444H). Full-gene sequencing is available and can identify up to 99% of causative mutations.
  • Genetic testing is possible for at-risk family members who may develop late-onset symptoms. Carriers can be diagnosed with 95% accuracy by enzyme assay, but DNA testing is superior for this purpose being less affected by temperature or sample handling.

If the Diagnosis is Confirmed

  • For evaluation and ongoing collaborative management, consult Medical Genetics (see RI providers [4]).
  • Educate the family regarding signs, symptoms, and the need for urgent care when the infant becomes ill.
  • Start oral biotin at 5mg bid and assure continuation for life in patients with profound biotinidase deficiency. Patients with partial deficiency might require lower doses after the first year of life.
  • For those identified after irreversible consequences, assist in management, particularly with low vision aids, hearing aids or cochlear implants, developmental and educational interventions.

Resources

Information & Support

Related Portal Content
Biotinidase Deficiency
Assessment and management information for the primary care clinician caring for the child with biotinidase deficiency.

Biotinidase Deficiency (FAQ)
Answers to questions families often have about caring for their child with biotinidase deficiency.

After a Diagnosis or Problem is Identified
Families can face a big change when their baby tests positive for a newborn condition. Find information about A New Diagnosis - You Are Not Alone; Caring for Children with Special Health Care Needs; Assistance in Choosing Providers; Partnering with Healthcare Providers; Top Ten Things to Do After a Diagnosis.

For Professionals

Biotinidase Deficiency (GeneReviews)
Detailed information addressing clinical characteristics, diagnosis/testing, management, genetic counseling, and molecular pathogenesis; from the University of Washington and the National Library of Medicine.

Resources for Biotinidase Deficiency (Disease InfoSearch)
Compilation of information, articles, and links to support.

For Parents and Patients

Biotinidase Deficiency (MedlinePlus)
Information for families that includes description, frequency, causes, inheritance, other names, and additional resources; from the National Library of Medicine.

Baby's First Test (Genetic Alliance)
Clearinghouse for local, state, and national newborn screening education, programs, policies, and resources. Also, provides many ways for people to connect and share their viewpoints and questions about newborn screening, supported by the U.S. Department of Health and Human Services.

Tools

Confirmatory Algorithm for Biotinidase Deficiency (ACMG) (PDF Document 224 KB)
An algorithm of the basic steps involved in determining the final diagnosis of an infant with a positive newborn screen; American College of Medical Genetics.

RI ACT Sheet for Biotinidase Deficiency (ACMG) (PDF Document 137 KB)
Provides recommendations for clinical and laboratory follow-up of the newborn with out-of-range screening results, along with national and local resources for clinicians and families; American College of Medical Genetics.

Services for Patients & Families in Rhode Island (RI)

For services not listed above, browse our Services categories or search our database.

* number of provider listings may vary by how states categorize services, whether providers are listed by organization or individual, how services are organized in the state, and other factors; Nationwide (NW) providers are generally limited to web-based services, provider locator services, and organizations that serve children from across the nation.

Helpful Articles

PubMed search on biotinidase deficiency and neonatal screening, last 8 years.

Wolf B.
Clinical issues and frequent questions about biotinidase deficiency.
Mol Genet Metab. 2010;100(1):6-13. PubMed abstract

Authors & Reviewers

Initial publication: March 2007; last update/revision: June 2012
Current Authors and Reviewers:
Authors: Kimberly Hart, MS, LCGC
Nicola Longo, MD, Ph.D.