A severe case of Frank-ter Haar syndrome and literature review: Further delineation of the phenotypical spectrum

Abstract

Frank-ter Haar syndrome (FTHS) is a rare autosomal recessive syndrome resulting from mutations in the SH3PXD2B gene involved in the formation of podosomes and invadopodia which have a role in extracellular matrix remodelling and cell migration. FTHS is characterized by facial dysmorphism, megalocornea, inconstant glaucoma, variable developmental delay, skeletal and cardiac anomalies. To date, 40 patients have been reported in the literature with a clinical diagnosis of FTHS, only 20 patients having identified mutations. We present a review of these 20 reported patients and describe a patient born to non-consanguineous parents, with intrauterine growth retardation, hypotonia, congenital glaucoma, caudal appendix, scoliosis, camptodactyly, ventricular septal defect, thin corpus callosum and craniofacial features suggestive of FTHS. Clinical evolution resulted in buphthalmos worsening, coarsening of the facial features and respiratory failure leading to death at 4,5 months. Diagnosis was confirmed by the identification of a previously known homozygous mutation c.969delG, p.(Arg324Glyfs*19) in SH3PXD2B. This is the first description of very severe phenotype with lethal respiratory impairment in FTHS. Since very few patients are described in the literature, and 2 out of the 3 patients carrying the c.969delG mutation had a favourable clinical course, more cases are needed to better characterize the phenotype and understand the natural history of this syndrome. Furthermore, we hypothesize that the alteration of podosomes function could lead to a reduction of the extracellular matrix degradation and accumulation of the latter in the extracellular space, which might explain the coarsening of the facial features and the severe refractory glaucoma.