Lipoid proteinosis: A clinical and molecular study in Egyptian patients

Lipoid proteinosis: Novel ECM1 pathogenic variants and intrafamilial variability in four unrelated Arab families

BACKGROUND/OBJECTIVES

Lipoid proteinosis (LP) is a rare autosomal recessive multisystem disorder that is caused by loss-of-function pathogenic variants in the extracellular matrix protein-1 (ECM1) gene. The typical clinical manifestations of LP include hoarseness of voice, beaded papules on the eyelids, infiltration and scarring of the skin and mucosa, as well as neuropsychological abnormalities. Currently, more than 70 pathogenic variants have been reported, including nonsense, missense, splice site, deletion and insertion pathogenic variants, and more than half of them occurred in exons 6 and 7.

METHODS

Clinical evaluation and Sanger sequencing were performed on eight patients from four unrelated Arab families.

RESULTS

We identified two novel ECM1 variants, one nonsense pathogenic variant in exon 6 (c.579G>A, p.Trp193*) and a deletion of three nucleotides (c.1390_1392del, p.Glu464del) in exon 9, and two previously reported frameshift variants; c.692_693delAG, in exon 6 and c.11dupC in exon 1.

CONCLUSIONS

Although all patients had characteristic manifestations of lipoid proteinosis, we observed intrafamilial phenotypic variability. Our data expand the pathogenic variant spectrum of ECM1 and also supports the fact that exon 6 is one of the most common hot spots of pathological variants in ECM1.

Extracellular Matrix Protein 1 Gene Mutation in Turkish Patients with Lipoid Proteinosis

Background:

Lipoid proteinosis (LP) is a rare autosomal recessive genodermatosis characterized by mucocutaneous lesions and hoarseness of voice that develop in early childhood. LP is caused by mutation in the extracellular matrix protein 1 (ECM1) gene, which is located on 1q21.2.

Aims:

This study aimed to present the profile of ECM1 gene mutations and to identify possible novel mutations specific to Turkey.

Materials and Methods:

The ECM1 gene mutations of 19 LP patients from five families were evaluated using DNA isolated from peripheral blood samples. All ten exons in the ECM1 gene region were amplified by polymerase chain reaction (PCR). The PCR products were analyzed using a DNA sequencing analyzer. The results of DNA sequencing were analyzed with bioinformatics methods.

Results:

of the 19 LP patients evaluated in our study, we detected defects in exon 6 (c.507delT, 658T>G), exon 9 (157C>T, 727C>T), and exon 10 (c.93_94delGCinsTT) of the ECM1 gene.

Conclusions:

Our results indicate that defects in exons 6, 9, and 10 of the ECM1 gene were responsible for LP in our country. The identification of these pathogenic mutations is valuable because it facilitates early diagnosis and genetic counseling.