A new form or a variant of SMD type A4

Spondylometaphyseal dysplasias have been classified by Maroteaux and Spranger (1991) as well as by Duetting et al. (1998) based on severity of the changes in the femoral neck and metaphyses as well as vertebral abnormalities. SMD type A4 (SMDTA4) is characterized by severe changes of the femoral neck, marked metaphyseal abnormalities and ovoid, flattened vertebral bodies with an anterior tongue-like deformity (Maroteaux and Spranger 1991; Duetting et al. 1998). In addition to classical SMDTA4 characteristics, our patient has progressive scoliosis and lack of ossification of the capital femoral epiphyses at the age of 11 years. A genetic defect that cause SMDTA4 is so far unknown. The Jansen type of SMD reported by Campbell et al. (2000), which is a phenotypic variant of Jansen metaphyseal chondrodysplasia, shares similar phenotypic features with our patient (Table 1). We decided to analyze the PTHR1 gene encoding PTH/PTHrP receptor for parathyroid hormone related peptide (PTHrP) and parathyroid hormone (PTH), since mutations in this gene are a known cause of Jansen metaphyseal chondrodysplasia (Schipani et al. 1999). Table 1 Phenotypic similarities and differences between patient with Jansen type of spondylometaphyseal dysplasia (Campbell et al., 2000) and reported patient