Axial spondylometaphyseal dysplasia: Additional reports

Abstract

Axial spondylometaphyseal dysplasia (SMD) (OMIM 602271) is an uncommon skeletal dysplasia characterized by metaphyseal changes of truncal-juxtatruncal bones, including the proximal femora, and retinal abnormalities. The disorder has not attracted much attention since initially reported; however, it has been included in the nosology of genetic skeletal disorders [Warman et al. (2011); Am J Med Genet Part A 155A:943-968] in part because of a recent publication of two additional cases [Isidor et al. (2010); Am J Med Genet Part A 152A:1550-1554]. We report here on the clinical and radiological manifestations in seven affected individuals from five families (three sporadic cases and two familial cases). Based on our observations and Isidor's report, the clinical and radiological hallmarks of axial SMD can be defined: The main clinical findings are postnatal growth failure, rhizomelic short stature in early childhood evolving into short trunk in late childhood, and thoracic hypoplasia that may cause mild to moderate respiratory problems in the neonatal period and later susceptibility to airway infection. Impaired visual acuity comes to medical attention in early life and function rapidly deteriorates. Retinal changes are diagnosed as retinitis pigmentosa or pigmentary retinal degeneration on fundoscopic examination and cone-rod dystrophy on electroretinogram. The radiological hallmarks include short ribs with flared, cupped anterior ends, mild spondylar dysplasia, lacy iliac crests, and metaphyseal irregularities essentially confined to the proximal femora. Equally affected sibling pairs of opposite gender and parental consanguinity are strongly suggestive of autosomal recessive inheritance.

Axial spondylometaphyseal dysplasia with retinitis pigmentosa—a clinical report and diagnostic clues

“…Patients with SDS can exhibit mild vertebral abnormality (usually square vertebral bodies; Nishimura et al 2007). This was noted in our case and in at least one of the patients described by Suzuki et al (2011); this patient received initially a tentative diagnosis of SDS. However, clinically, patients with SDS should have evidence of pancreatic insufficiency or hematological abnormalities (cytopenia of at least one lineage) that are required for establishment of the clinical diagnosis.…”

“…Notably, although the patient reported here was closely followed for color blindness, nystagmus, and amblyopia since the age of 2 years, clinically apparent retinal changes were identified only at 16 years of age, leading to the clinical diagnosis. In previous reports, retinitis pigmentosa was diagnosed as early as in the neonatal period (age 3 weeks; Suzuki et al 2011) and up to 9 years of age; a few of the reported patients ultimately became blind (Krakow et al 2009; Isidor et al 2010). …”

“…The patient reported here presented with early-onset postnatal short stature with a peculiar chest deformity and progressive retinal dystrophy that was only identified at the age of 16 years, supporting a diagnosis of SMD axial type with retinal degeneration (Krakow et al 2009; Isidor et al 2010). Suzuki et al (2011) have recently delineated the phenotype of axial SMD in seven individuals. The radiological hallmarks include short ribs with flared, cupped anterior ends, mild vertebral changes, infrequent lacy iliac crests, and metaphyseal irregularities essentially confined to the proximal femurs.…”

“…It is unclear as to whether SMD with cone–rod dystrophy is a separate or allelic entity (the radiographic changes are much more severe). Suzuki et al’s report includes an equally affected sibling pair of opposite gender and parental consanguinity, suggestive that axial SMD is recessively inherited (Suzuki et al 2011). Notably, although the patient reported here was closely followed for color blindness, nystagmus, and amblyopia since the age of 2 years, clinically apparent retinal changes were identified only at 16 years of age, leading to the clinical diagnosis.…”

Spondylometaphyseal dysplasia: an uncommon disease

“…The symptoms of SMD vary depending on the age of the patients (1) , the principal symptoms being as follows: limited postnatal growth; rhizomelic shortening of the limbs in early childhood evolving to shortening of the trunk by the age of 10 years; thoracic hypoplasia, which causes respiratory problems in the neonatal period and increases susceptibility to respiratory tract infection (4) ; scoliosis with dorsal kyphosis; abnormalities of the metaphyses and pelvis (5) ; odontoid hypoplasia; and valgus of the knees and claudication (6) , the latter typically being the first sign of the disease (2) . There might be little or no ossification of the cervical vertebrae, leading to cervical instability and swan neck deformity (7) .…”