title: Infantile malignant osteopetrosis: a rare cause of neonatal hypocalcemia.
abstract: Infantile malignant osteopetrosis (IMO; OMIM 259700) is a rare inherited bone disease characterized by reduced or dysregulated activity of osteoclasts, resulting in generalized osteosclerosis. The disease usually presents within the first few months of life with anemia, hepatosplenomegaly, frontal bossing, nystagmus, blindness, deafness, and bone fractures. Children with IMO are at risk of developing hypocalcemia, with attendant tetanic seizures. We report the case of a baby boy who presented with neonatal hypocalcemia. Skeletal radiographs demonstrated sclerotic bones and a dense base of the skull with typical "space alien" face confirming the diagnosis of IMO. Pancytopenia developed at 2 months of age. Visual evoked potential showed severe bilateral optic nerve damage. Genetic mutation study revealed a new mutation in exon 13 of the TCIRG1 gene. Neonatal hypocalcemia can occur as result of IMO, which is easily missed out by clinicians. This causes delay in establishing the diagnosis and starting necessary treatment. Therefore, osteopetrosis should be kept in mind as a rare cause of neonatal hypocalcemia.
authors: Department of Pediatric Endocrinology, Ankara Training and Research Hospital, Ankara, Turkey. oengiz@yahoo.com
authors: Ozlem
authors: O
authors: Engiz
authors: Semra
authors: S
authors: Kara
authors: Denizhan
authors: D
authors: Bagrul
authors: Georgia
authors: G
authors: Lahr
authors: Bulent
authors: B
authors: Alioglu
authors: Inci
authors: I
authors: Arikan
authors: Yıldız Dallar
authors: YD
authors: Bilge
mesh_terms: D001842:Bone and Bones / Q000000981:diagnostic imaging; D006801:Humans; D006996:Hypocalcemia / Q000151:congenital / Q000175:diagnosis* / Q000209:etiology; D007231:Infant, Newborn; D008297:Male; D020125:Mutation, Missense; D009900:Optic Nerve / Q000002:abnormalities; D010022:Osteopetrosis / Q000150:complications / Q000151:congenital / Q000175:diagnosis*; D011859:Radiography; D025262:Vacuolar Proton-Translocating ATPases / Q000235:genetics
chemical_list: C472421:TCIRG1 protein, human; D025262:Vacuolar Proton-Translocating ATPases