Title : Expanding the phenotypic spectrum of apmr4 syndrome caused by a novel variant in lss gene and review of literature
Alopecia intellectual disability syndromes 4 (APMR4) is a very rare autosomal recessive condition caused by a mutation in the LSS gene present on chromosome 21. This syndrome has a clinical heterogeneity mainly exhibited with variable degrees of intellectual disability (ID) and congenital alopecia, as well. Eight families with 13 cases have been previously reported.
Herein, we provide a report on an Egyptian family with two afected siblings and one afected fetus who was diagnosed pre-natally. Whole-exome sequencing (WES) revealed a novel pathogenic missense variant (c.1609G>T; p.Val537Leu) in the lanosterol synthase gene (LSS) related to the examined patients. The detected variant was confrmed by Sanger sequencing. Segregation analyses confrmed that the parents were heterozygous. Our patient was presented with typical clinical mani-festations of the disease in addition to new phenotypic features which included some dysmorphic facies as frontal bossing and bilateral large ears, as well as bilateral hyperextensibility of the fngers and wrist joints, short stature, umbilical hernia, and teeth mineralization defect. This study is the frst study in Egypt and the 9th molecularly proven family to date. The aim is to expand the clinical and mutational spectrum of the syndrome. Moreover, the report gives a hint on the importance of prenatal testing and the proper genetic counseling to help the parents to take their own decision based on their beliefs.
Keywords: Whole-exome sequencing · Segregation · Alopecia-intellectual disability syndrome 4 (APMR4) · LSS gene