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A case of achondrogenesis type IA with an occipital encephalocele
1Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan, Republic of China.
Insights
This study details a rare case of achondrogenesis type IA, a severe skeletal dysplasia, co-occurring with an occipital encephalocele, a neural tube defect. This combination has not been previously documented in medical literature.
Area of Science:
- Medical Genetics
- Developmental Biology
- Pediatric Pathology
Background:
- Achondrogenesis type IA (Houston-Harris) is a severe, lethal skeletal dysplasia characterized by extreme micromelia and lack of ossification.
- Neural tube defects are common congenital abnormalities, but their association with achondrogenesis type IA is unprecedented.
Observation:
- Prenatal ultrasound revealed polyhydramnios, edema, microcephaly, narrow thorax, pericardial effusion, and severe short-limbed dwarfism.
- Postmortem examination confirmed hydrops fetalis, membranous calvarium with defect, occipital encephalocele, hypoplastic lungs, and abnormal bone morphology.
- Radiography showed virtually no bone ossification, with minimal calcification in the skull base, clavicles, and pelvis.
Findings:
- Histological analysis of growth plates revealed hypercellularity and enlarged chondrocytes with specific cytoplasmic inclusions.
- This case represents the first documented instance of achondrogenesis type IA associated with an occipital encephalocele.
- The severe skeletal abnormalities were accompanied by a significant neural tube defect.
Implications:
- This report expands the known phenotypic spectrum of achondrogenesis type IA.
- Highlights the importance of comprehensive evaluation in cases of severe skeletal dysplasia.
- Suggests potential shared or interacting pathways in the pathogenesis of skeletal and neural tube development.
Abstract:
We report on a case of achondrogenesis type IA (Houston-Harris) with an occipital encephalocele. Prenatal sonograms revealed polyhydramnios, subgaleal edema, microcephaly, a narrow thorax, pericardial effusion, and a severe short-limbed dwarfism with unossified tubular bones and vertebral bodies. Postmortem examination demonstrated additional findings of hydrops fetalis, a membranous calvarium with a defect, an occipital encephalocele, hypoplastic lungs, and wedge-like tubular bones. Whole body radiography revealed no ossification of the bones except some small identified foci of calcification in the base of the skull, clavicles, and pelvic bones. Histological examination of the growth plate showed hypercellularity and enlarged vacuolated chondrocytes with PAS-positive diastase-resistant cytoplasmic inclusions. Various abnormalities have been reported in association with achondrogenesis type IA, however, an associated neural tube defect has not previously been described in the literature. We report on an infant with both of these disorders.