Mutational analysis of the lysyl hydroxylase 1 gene (PLOD) in six unrelated patients with Ehlers-Danlos syndrome type VI: prenatal exclusion of this disorder in one family

Abstract

Screening of full length cDNAs for lysyl hydroxylase 1 (LH1; also PLOD) amplified from dermal fibroblasts from six unrelated patients with the autosomal recessive disorder Ehlers-Danlos syndrome type VI (EDS VI) has shown them to be both homozygous and compound heterozygous for mutations in the gene. These mutations, which were verified in genomic DNA, result in a deficiency of LH activity (<25% of normal) in the probands, who are clinically characterized by kyphoscoliosis and extensibility of skin and joints. Four novel mutations identified in these patients include a mutation of an inserted C in one homozygous patient (1702insC) and three point mutations resulting in premature termination codons (PTCs): Y142X, Q327X (in two patients), and R670X. In the family with the R670X mutation we have prenatally excluded EDS VI by the characterization of mutations and their allelic inheritance. We have identified two previously reported mutations in the new patients: a seven exon duplication (in two patients) and a point mutation that codes for a PTC, Y511X, (in two patients). Genotype analysis indicated that the Y511X mutation may originate from a common ancestral gene. Several alternative splicing pathways have been identified which bypass the PTCs and can also restore the open reading frame.