title: Severe neuronopathic autosomal recessive osteopetrosis due to homozygous deletions affecting OSTM1.
abstract: Autosomal recessive osteopetrosis (ARO, MIM 259700) is a genetically heterogeneous rare skeletal disorder characterized by failure of osteoclast resorption leading to pathologically increased bone density, bone marrow failure, and fractures. In the neuronopathic form neurological complications are especially severe and progressive. An early identification of the underlying genetic defect is imperative for assessment of prognosis and treatment by hematopoietic stem cell transplantation. Here we describe for the first time homozygous microdeletions of different sizes affecting the OSTM1 gene in two unrelated consanguineous families with children suffering from neuronopathic infantile malignant osteopetrosis. Patients showed an exceptionally severe phenotype with variable CNS malformations, seizures, blindness, and deafness. Multi-organ failure due to sepsis led to early death between six weeks and five months of age in spite of intensive care treatment. Analysis of the breakpoints revealed different mechanisms underlying both rearrangements. Microdeletions seem to represent a considerable portion of OSTM1 mutations and should therefore be included in a sufficient diagnostic screening.
authors.affiliation: Institute of Medical Genetics and Human Genetics, Charité - Universitaetsmedizin Berlin, Berlin, Germany.
authors.forename: Claus-Eric
authors.initials: CE
authors.lastname: Ott
authors.forename: Björn
authors.initials: B
authors.lastname: Fischer
authors.forename: Phillipe
authors.initials: P
authors.lastname: Schröter
authors.forename: Reyk
authors.initials: R
authors.lastname: Richter
authors.forename: Neerja
authors.initials: N
authors.lastname: Gupta
authors.forename: Nishant
authors.initials: N
authors.lastname: Verma
authors.forename: Madhulika
authors.initials: M
authors.lastname: Kabra
authors.forename: Stefan
authors.initials: S
authors.lastname: Mundlos
authors.forename: Anna
authors.initials: A
authors.lastname: Rajab
authors.forename: Heidemarie
authors.initials: H
authors.lastname: Neitzel
authors.forename: Uwe
authors.initials: U
authors.lastname: Kornak
mesh_terms: D001483:Base Sequence; D003241:Consanguinity; D005260:Female; D017353:Gene Deletion; D006720:Homozygote; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D010022:Osteopetrosis / Q000151:congenital* / Q000235:genetics / Q000473:pathology; D010375:Pedigree; D060888:Real-Time Polymerase Chain Reaction; D044767:Ubiquitin-Protein Ligases / Q000235:genetics*
chemical_list: D008565:Membrane Proteins; C489946:OSTM1 protein, human; D044767:Ubiquitin-Protein Ligases