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The overall prevalence of OI is estimated at between 1/10,000 and 1/20,000 but the prevalence of type II is unknown.

There are three subtypes of OI type II (A, B and C) that are characterized by different radiological features. Patients with OI type IIA present with broad ribs with multiple fractures, continuous beaded ribs and severe under-modeling of the femur. OI type IIB presents with normal or thin ribs with some fractures, discontinuous beaded ribs and some under-modeling of the femur. OI type IIC presents with varying thickness of the ribs, discontinuous beading of the ribs, malformed scapulae and ischiae, and long bones with thin shafts and expanded metaphyses. Type IIC is extremely rare and its existence is even doubted.

Variants in the COL1A1 and COL1A2 genes (17q21.31-q22 and 7q22.1 respectively) cause OI type IIA and IIB, and transmission is autosomal dominant. Type IIB can also be autosomal recessive, caused by mutations in the CRTAP gene (3p22; sometimes described as OI type VII) or the P3H1 gene (1p34; sometimes described as OI type VIII) or the PPIB gene (15q21-q22; sometimes described as OI type IX). OI type IIC appearances have been reported in fetuses with mutations in the MESD gene (15q25).

Diagnosis is typically prenatal due to suspicious ultrasound findings.

Differential diagnosis includes thanatophoric dwarfism, severe hypophosphatasia, and mucolipidosis type II.

Prenatal diagnosis of type II OI may be suggested by fetal ultrasound appearances, and confirmed by genetic testing of amniocytes.

The disease is either autosomal dominant or autosomal recessive depending on the gene involved. Autosomal dominant cases occur either sporadically or due to germline mosaicism. The appropriate genetic counseling should be offered to affected families.

Management is initially expectant; some infants with apparently very severe changes on ultrasound may nevertheless survive with intensive support and early institution of bone-directed therapy such as bisphosphonates.

The majority of those identified of having type II changes antenatally will die either before birth or in the perinatal period. A few may survive with continued intensive treatment.