Fanconi Anemia Type B: FANCB Gene Deletion/Duplication

Condition Description

Fanconi anemia (FA) is characterized by physical abnormalities.  Approximately 60-75% of affected individuals have variable physical abnormalities which may include short stature, abnormal skin pigmentation, skeletal anomalies, and ear or eye abnormalities.  Other features include heart defects, hearing loss, developmental delay, hypogonadism, and genitourinary tract abnormalities.

FA is diagnosed by the detection of chromosomal aberrations in cells that have been cultured with a DNA interstrand cross-linking agent.  There are at least 15 genes that are responsible for the known FA complementation groups. Mutations in the FANCB gene (Xp22.31) (OMIM# 300515), which are responsible for FA complementation group B (FA-B) (OMIM# 300514), account for 2% of FA cases.  FA-B cases are the only X-linked form of FA and mainly affect males.  Females can be heterozygote carriers at risk for having a child with X-linked FA.  Carriers are found to have 100% skewing of X inactivation.

This testing is for sequence analysis of the FANCB gene only.

For patients with suspected FA-B, sequence analysis is recommended as the first step in mutation identification. For patients in whom mutations are not identified by full gene sequencing, deletion/duplication analysis is appropriate.


Genes (1)


This test is indicated for:
  • Confirmation of a clinical diagnosis of Fanconi Anemia Type B in an individual in whom sequence analysis was negative.
  • Carrier testing in adults with a family history of Fanconi Anemia Type B in whom sequence analysis was negative.


DNA isolated from peripheral blood is hybridized to a CGH array to detect deletions and duplications. The targeted CGH array has overlapping probes which cover the entire genomic region.


Detection is limited to duplications and deletions. The CGH array will not detect point or intronic mutations. Results of molecular analysis must be interpreted in the context of the patient's clinical and/or biochemical phenotype.

Specimen Requirements

Listed below are EGL's preferred sample criteria. For any questions, please call 470.378.2200 and ask to speak with a laboratory genetic counselor (
Submit only 1 of the following specimen types
DNA, Isolated

Isolation using the Perkin Elmer™Chemagen™ Chemagen™ Automated Extraction method or Qiagen™ Puregene kit for DNA extraction is recommended.
Collection and Shipping
Refrigerate until time of shipment in 100 ng/µL in TE buffer. Ship sample at room temperature with overnight delivery.
Whole Blood (EDTA)

EDTA (Purple Top)
Infants and Young Children (<2 years of age): 2-3 ml
Children > 2 years of age to 10 years old: 3-5 ml
Older Children & Adults: 5-10 ml
Autopsy: 2-3 ml unclotted cord or cardiac blood
Collection and Shipping
Ship sample at room temperature for receipt at EGL within 72 hours of collection. Do not freeze.
  • Sequence analysis of the FANCB gene is available and is required before deletion/duplication analysis.  
  • Custom diagnostic mutation analysis (KM) is available to family members if mutations are identified by targeted mutation testing or sequencing analysis.
  • Prenatal testing is available only for known familial mutations to individuals who are confirmed carriers of mutations. Please contact the laboratory genetic counselor to discuss appropriate testing prior to collecting a prenatal specimen.
  • X-Linked Intellectual Disability panels are available for 30, 60, and 90 genes.

How to Order