Genetic homogeneity of lysinuric protein intolerance

Lysinuric protein intolerance (LPI) is an autosomal recessive disorder in w hich transport of the cationic amino acids lysine, arginine and ornithine i s defective at the basolateral membrane of the epithelial cells in the inte stine and renal tubules. LPI is unusually common in Finland, but patients h ave been described on all continents. Linkage analysis in Finnish LPI famil ies recently assigned the LPI gene locus to a 10 cM interval between marker s D14S72 and MYH7 on the long arm of chromosome 14. In the present study li nkage analysis of LPI families from six different non-Finnish populations s trongly suggests genetic homogeneity in LPI. Peak lod scores were obtained at the chromosomal area between D14S72 and MYH7 with the same markers as in the Finnish families. The non-finnish families showed no linkage disequili brium except in an Italian family cluster, whereas strong allelic associati on in the Finnish families implies that LPI in Finland is caused by a found er mutation.