PubMed · 5564166
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B A Walker, J L Murdoch, V A McKusick, L O Langer, R K Beals. 1971. Hypochondroplasia.. https://doi.org/10.1001/archpedi.1971.02110020029001
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Achondroplasia is the most common form of short-limbed dwarfism in humans and is caused by mutations in the FGFR3 gene. Currently, prenatal diagnosis of this disorder relies on invasive procedures. Recent studies have shown that fetal single gene point mutations could be detected in cell-free DNA (cf-DNA) from maternal plasma by either the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) assay with single allele base extension reaction (SABER) approach or the size fractionation of cf-DNA in maternal plasma. Here, we combined the two approaches to non-invasively examine the fetal G1138A mutation in maternal plasma. cf-DNA was extracted from maternal plasma samples obtained from two pregnant women at risk for achondroplasia. The fetal G1138A mutation was determined by the analysis of size-fractionated cf-DNA in maternal plasma using MALDI-TOF MS with SABER approach and homogenous MassEXTEND (hME) assay, respectively. The fetal G1138A mutation was detectable in the two achondroplasia-affected pregnancies by the analysis of cf-DNA in maternal plasma using MALDI-TOF MS. However, the size-fractionation approach led to a more precise detection of the fetal mutation in both analyses. This analysis would be suitable for non-invasive prenatal diagnosis of diseases caused by fetal single gene point mutations.
OBJECTIVE: To study in children with achondroplasia the response to exercise and muscle strength compared with healthy peers and to describe the relation between exercise capacity, anthropometric factors, and physical activity. STUDY DESIGN: Patients (7 boys and 10 girls; mean age, 11.8 +/- 3.3 years) with achondroplasia performed a maximal treadmill exercise test. Anthropometric variables and muscle strength were measured and compared with the general population. The level of everyday physical activity was measured by using a diary. Functional ability was measured by using the Activity Scale for Kids. RESULTS: The exercise capacity of the children with achondroplasia was significantly reduced compared with reference values. All anthropometrical measurements differed significantly from reference values. There was a decrease in muscle strength in almost all muscle groups. We found a reduced physical activity level and impairments in functional ability. CONCLUSIONS: Cardiopulmonary exercise capacity and muscle strength in children with achondroplasia was reduced compared with reference values. Children with achondroplasia have a unique response to exercise. Clinicians should take these characteristic differences into account when the exercise capacity of subjects with achondroplasia is being tested.
For safe pedicle screw insertion, knowing pedicle anatomy is essential. Pedicle morphometry in achondroplasia has not been quantitatively described. Therefore, we analyzed 302 thoracic and lumbar pedicles in 11 patients using computed tomography. Transverse endosteal diameter, screw path length, transverse angle, sagittal diameter, and sagittal angle were calculated. We analyzed for safe screw length, size, and trajectory. The data were compared with that on healthy people of different races. In patients with achondroplasia, the maximum endosteal diameter was at L5 and the minimum was at T5. Screw path length was longest at L2 and shortest at T2. Most dimensions were smaller compared with those of healthy people. Abnormal anteromedial transverse angulations were observed between T11 to L2. The maximum transverse angulations were at T2. Sagittal diameter was largest at T12 and smallest at T5. The maximum sagittal angle was seen at T2, and at L5 it was caudal. At all levels except L5, the transverse diameter is the limiting factor for screw size. Six-millimeter screws can be used at L5. Screws that are 35 mm or less are safe to use between T7 to L5. There are surgically important differences in the different angles and diameters of thoracic and lumbar pedicles of patients with achondroplasia and those of healthy people.