This site is intended for healthcare professionals
Journals
  • Home
  • /
  • Journals
  • /
  • Other hereditary or degenerative neurological diso...
  • /
  • Genetic risk assessment in carrier testing for spi...
Journal

Genetic risk assessment in carrier testing for spinal muscular atrophy.

Read time: 1 mins
Published:14th Jul 2002
Author: Ogino S, Leonard DG, Rennert H, Ewens WJ, Wilson RB.
Availability: Pay for access, or by subscription
Ref.:Am J Med Genet. 2002;110(4):301-7.
DOI:10.1002/ajmg.10425

As evidenced by the complete absence of a functionally critical sequence in exon 7, approximately 94% of individuals with clinically typical spinal muscular atrophy (SMA) lack both copies of the SMN1 gene at 5q13. Hence most carriers have only one copy of SMN1. Combining linkage and dosage analyses for SMN1, we observed unaffected individuals who have two copies of SMN1 on one chromosome 5 and zero copies of SMN1 on the other chromosome 5. By dosage analysis alone, such individuals, as well as carriers of non?deletion disease alleles, are indistinguishable from non?carrier individuals. We report that approximately 7% of unaffected individuals without a family history of SMA have three or four copies of SMN1, implying a higher frequency of chromosomes with two copies of SMN1 than previously reported. We present updated calculations for disease and non?disease allele frequencies and we describe how these frequencies can be used for genetic risk assessment in carrier testing for SMA.

Read abstract on library site

Access full article