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Fukuyama Congenital Muscular Dystrophy via the FKTN Japanese Founder Mutation

Summary and Pricing

Test Method

Bi-Directional Sanger Sequencing
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
FKTN 81479 81479 $350
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
354FKTN81479 81479 $350 Order Options and Pricing

Pricing Comments

CNV detection may be ordered through Test #600.

An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.

Turnaround Time

4 weeks on average for standard orders or 2 weeks on average for STAT orders.

Please note: Once the testing process begins, an Estimated Report Date (ERD) range will be displayed in the portal. This is the most accurate prediction of when your report will be complete and may differ from the average TAT published on our website. About 85% of our tests will be reported within or before the ERD range. We will notify you of significant delays or holds which will impact the ERD. Learn more about turnaround times here.

Targeted Testing

For ordering sequencing of targeted known variants, go to our Targeted Variants page.


Genetic Counselors


  • Angela Gruber, PhD

Clinical Features and Genetics

Clinical Features

Mutations in FKTN cause muscular dystrophies in the dystroglycanopathy spectrum, the most severe of which is Walker-Warburg syndrome (WWS, OMIM 236670; Beltran-Valero de Bernabe et al. J. Med. Genet. 40:845-848, 2003). Patients with WWS typically die at birth or shortly thereafter due to complications from severe CNS structural abnormalities. Fukuyama congenital muscular dystrophy (FCMD, OMIM 253800) is a less severe phenotype and is the second most common muscular dystrophy among Japanese people (Kobayashi et al. Nature 394:388-392, 1998). In the vast majority of cases the causative mutation is an inserted 3 kb retrotransposon at the 3’ UTR of the FKTN gene. Patients who are compound heterozygous for the Japanese founder mutation and an FKTN coding mutation may have more severe WWS-like features than homozygous founder mutation patients (Kondo-Iida, et al. Hum. Molec. Genet. 8:2303-2309, 1999). A third reported variant is limb girdle muscular dystrophy due to FKTN mutations (Godfrey et al. Ann Neurol 60;603-610, 2006). These patients are responsive to steroid treatment and, unlike WWS and FCMD patients, are able to ambulate and have normal intelligence and normal brain structure.


The FKTN-related disorders are inherited in an autosomal recessive manner. Although the retrotransposon mutation is the most commonly reported pathogenic variant, mutations of other forms are found throughout the gene. Mutations in FKTN lead to reduced glycosylation of alpha-dystroglycan (ADG), a component of the dystrophin-glycoprotein complex (Ervasti et al. Nature 345:315-319). Evaluation of a patient’s muscle biopsy by immunofluorescence can detect abnormal glycosylation of ADG and can, therefore, help direct a diagnostic evaluation. It should be noted that at least six other genes (POMT1, POMT2, ISPD, POMGnT1, FKRP, LARGE) encode proteins required for processing of ADG, and that overlap exists between clinical phenotypes resulting from mutations in these genes.

Clinical Sensitivity - Sanger Sequencing

This test will only detect the Japanese founder mutation underlying Fukuyama congenital muscular dystrophy.  Mutations in the FKTN coding sequence can be ascertained by sequence analysis.  Because LGMD and CMD demonstrate extensive locus and allelic heterogeneity, a negative FCMD result does not rule out a diagnosis of these disorders when classic clinical findings are present.  If a muscle biopsy is available, immunostaining may also be an appropriate diagnostic approach.

Testing Strategy

Fukutin is coded by exons 2-10 of the FKTN gene located on chromosome 9q31. Testing for the presence/absence of the Japanese ancestral retrotransposon is accomplished by polymerase chain reaction.

Indications for Test

Individuals of Japanese descent with symptoms consistent with Fukuyama congenital muscular dystrophy or WWS-like presentations. Individuals with immunofluorescence results demonstrating hypoglycosylation of ADG in muscle.


Official Gene Symbol OMIM ID
FKTN 607440
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Related Tests

Comprehensive Cardiology Panel
Dystroglycanopathy via the FKTN Gene
Sudden Cardiac Arrest Panel


  • de Bernabe, D. B., et.al. (2003). "A homozygous nonsense mutation in the fukutin gene causes a Walker-Warburg syndrome phenotype." J Med Genet 40(11): 845-8. PubMed ID: 14627679
  • Ervasti, J. M., et.al. (1990). "Deficiency of a glycoprotein component of the dystrophin complex in dystrophic muscle." Nature 345(6273): 315-9. PubMed ID: 2188135
  • Godfrey, C., et.al. (2006). "Fukutin gene mutations in steroid-responsive limb girdle muscular dystrophy." Ann Neurol 60(5): 603-10. PubMed ID: 17044012
  • Kobayashi, K., et.al. (1998). "An ancient retrotransposal insertion causes Fukuyama-type congenital muscular dystrophy." Nature 394(6691): 388-92. PubMed ID: 9690476
  • Kondo-Iida, E., et.al. (1999). "Novel mutations and genotype-phenotype relationships in 107 families with Fukuyama-type congenital muscular dystrophy (FCMD)." Hum Mol Genet 8(12): 2303-9. PubMed ID: 10545611


Ordering Options

We offer several options when ordering sequencing tests. For more information on these options, see our Ordering Instructions page. To view available options, click on the Order Options button within the test description.

myPrevent - Online Ordering

  • The test can be added to your online orders in the Summary and Pricing section.
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  • Billing information along with specimen and shipping instructions are within the requisition form.
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For Requisition Forms, visit our Forms page

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