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Prenatal diagnosis and carrier detection of Niemann-Pick type C disease

As Niemann-Pick type C disease (NP-C) is an autosomal recessive condition, for each pregnancy there is:

  • a 25% probability that the offspring of a NP-C carrier couple will receive both mutated NP-C genes and inherit the disease
  • a 50% probability that the offspring will be a carrier
  • a 25% probability the offspring will neither inherit NP-C nor be a carrier.1

NP-C carriers can be identified via molecular analysis of NPC1 or NPC2 genes if it has been confirmed that a family has an NPC1 or NPC2 mutation. Biochemical testing is not appropriate as it cannot reliably differentiate between carriers and non-carriers.2

Prenatal diagnosis should be offered to couples with an affected child with NP-C. This can be achieved by either biochemical testing (only if the ‘classic' phenotype has been established in the proband) or genetic testing (only if NPC1 or NPC2 mutations have been identified in the proband) of fetal cells obtained via amniocentesis at 15-18 weeks or chorionic villus sampling at 10-12 weeks.1,2

Genetic counseling
Genetic counseling should be offered to individuals and families affected by NP-C, including those who are carriers, or at risk of being carriers.1,2 Providing information on the genetic risks (i.e. the best time to determine genetic risk, clarification of carrier status, prenatal testing etc.) will enable individuals to make informed decisions, particularly regarding family planning.1,2

References

  1. Wraith JE, Imrie J. Understanding Niemann-Pick disease type C and its potential treatment. UK Blackwell Publishing, 2007.
  2. Patterson MC, Hendriksz CJ, Walterfang M, et al, on behalf of the NP-C Guidelines Working Group. Recommendations for the diagnosis and management of Niemann–Pick disease type C: An update. Mol Genet Metab 2012. 106(3):330-344.