Table 2.

Summary of the key clinical manifestations, onset, severity, treatment, prognosis and recurrence risks of the main types of osteopetrosis

Osteopetrosis subtype	Autosomal recessive osteopetrosis (ARO)			X-linked osteopetrosis, lymphedema, anhidrotic ectodermal dysplasia and immunodeficiency (OLEDAID)	Intermediate osteopetrosis (IRO)	Autosomal dominant osteopetrosis (Albers-Schönberg disease)
	Classic	Neuropathic	ARO with RTA
Genetic basis	TCIRG	CLCN7, OSTM1	Carbonic anhydrase II	IKBKG (NEMO)	CLCN7, PLEKHM1	CLCN7
Skeletal manifestations			Increased bone density, diffuse and focal sclerosis of varying severity Modelling defects at metaphyses Pathological fractures Osteomyelitis Dental abnormalities: tooth eruption defects and dental caries
Other manifestations	Pancytopaenia. Extramedullary haematopoiesis, hepatosplenomegaly. Cranial nerve compression (II, VII, VIII) Hydrocephalus Hypocalcaemia	As for classic ARO, but primary neurodegeneration, including retinal atrophy	Renal tubular acidosis. Developmental delay. Intracranial calcification. Cranial nerve compression. Bone marrow impairment rare.	Anhidrotic ectodermal dysplasia. Lymphedema. Immunodeficiency resulting in overwhelming infection.	Anaemia and extramedullary haematopoiesis Occasional optic nerve compression	Moderate haematological failure Cranial nerve compression
Onset	Perinatal	Perinatal	Infancy	Infancy	Childhood	Late childhood or adolescence
Severity	Severe	Severe	Moderate	Severe	Mild to moderate	Mild to moderate, occasionally severe
Treatment	Supportive HSCT	Supportive	Supportive May benefit from HSCT	Supportive	Supportive	Supportive
Prognosis	Poor Fatal in infancy	Poor Fatal in infancy	Variable	Poor Fatal in early childhood	Variable	Normal life expectancy
Recurrence risk	Parents of proband: 25% risk of recurrence in future pregnancies			If mother of proband carrier: 50% of male pregnancies affected	Parents of proband: 25% risk of recurrence in future pregnancies	50% in future pregnancies if one parent affected