Prenatal mucolipidosis type II (I-cell disease) can present as Pacman dysplasia

Area of Science:

• Genetics and rare diseases
• Skeletal dysplasias
• Lysosomal storage disorders

Background:

• Pacman dysplasia is a lethal skeletal dysplasia characterized by epiphyseal stippling and osteoclastic overactivity.
• Previous reports described Pacman dysplasia as a distinct entity.
• The phenotypic spectrum of rare genetic disorders can be complex and overlapping.

Observation:

• A sibling of a fetus diagnosed with Pacman dysplasia presented with a clinical course consistent with Mucolipidosis type II (ML-II).
• Biochemical, cytologic, and radiographic evidence confirmed the diagnosis of ML-II in this infant.
• Re-evaluation of a previously reported case of Pacman dysplasia indicated ML-II.

Findings:

• The infant's condition, initially considered Pacman dysplasia, was definitively diagnosed as Mucolipidosis type II (I-cell disease).
• This case demonstrates that Pacman dysplasia may represent a phenotypic variant of ML-II.
• The findings challenge the classification of Pacman dysplasia as a separate disorder.

Implications:

• This study suggests that previously reported cases of Pacman dysplasia may be misdiagnosed instances of ML-II.
• Redefining Pacman dysplasia expands the known phenotypic spectrum of Mucolipidosis type II.
• Accurate diagnosis is crucial for understanding rare genetic conditions and providing appropriate care.