title: Prenatal sonographic diagnosis of hypochondroplasia in a high-risk fetus.
abstract: Hypochondroplasia (HCH) is caused by mutations in the fibroblast growth factor receptor type 3 (FGFR 3). Prenatal diagnosis of HCH based exclusively on the sonographic measurements of the fetal skeleton is difficult and has not been reported. We describe a newborn infant with HCH who was born to a mother with achondroplasia (ACH) and a father with HCH. Serial sonographic measurements were recorded from 16 weeks of gestation. All measurements remained normal up to 22 weeks of gestation. At 25 weeks of gestation, the long bones began to appear shorter than expected for gestational age, while the head measurements (biparietal diameter and head circumference) remained normal. The measurements were sufficiently different to distinguish from findings in normal and achondroplastic fetuses. Our findings suggest that it is possible to distinguish the normal fetus from a fetus affected with HCH and to distinguish HCH and ACH from each other based on the sonographic measurements alone. To our knowledge, this is the first report of longitudinal sonographic measurements of HCH in the second and third trimesters.
authors.affiliation: Department of Obstetrics and Gynecology, Hamilton Health Sciences Corporation, and McMaster University, Hamilton, Ontario, Canada.
authors.forename: M J
authors.initials: MJ
authors.lastname: Huggins
authors.forename: J R
authors.initials: JR
authors.lastname: Mernagh
authors.forename: L
authors.initials: L
authors.lastname: Steele
authors.forename: J R
authors.initials: JR
authors.lastname: Smith
authors.forename: M J
authors.initials: MJ
authors.lastname: Nowaczyk
mesh_terms: D000130:Achondroplasia / Q000235:genetics; D000328:Adult; D019943:Amino Acid Substitution; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000196:embryology; D005315:Fetal Diseases / Q000000981:diagnostic imaging* / Q000196:embryology / Q000235:genetics; D005838:Genotype; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D010009:Osteochondrodysplasias / Q000000981:diagnostic imaging* / Q000196:embryology / Q000235:genetics; D017354:Point Mutation; D011247:Pregnancy; D011248:Pregnancy Complications; D011262:Pregnancy Trimester, Second; D018566:Pregnancy, High-Risk; D011505:Protein-Tyrosine Kinases; D051498:Receptor, Fibroblast Growth Factor, Type 3; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics*; D016216:Ultrasonography, Prenatal
chemical_list: D017468:Receptors, Fibroblast Growth Factor; C496365:FGFR3 protein, human; D011505:Protein-Tyrosine Kinases; D051498:Receptor, Fibroblast Growth Factor, Type 3