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GENATLAS PHENOTYPE
last update : 30-04-2013
Symbol SMD2
Location 9p13.3
Name spondylometaphyseal dysplasia 2, Menger type
Other name(s)
  • anauxetic dysplasia
  • spondylometaepiphyseal dysplasia, anauxetic type 1
  • Corresponding gene RMRP
    Other symbol(s) SMDA1
    Main clinical features
  • extreme disproportionate short stature, distinct facial appearance with hypotelorism, prognathism, and hypodontia, short trunk with lumbar hyperlordosis, kyphoscoliosis, rhizomelic shortening of the limbs with brachydactyly of the hands and feet, extreme dwarfism resulting from a severe pre- and postnatal disturbance of skeletal growth and differentiation; radiographic characteristics are late-maturating, ovoid vertebral bodies with concave dorsal surfaces in the lumbar region, small capital femoral epiphyses, hypoplastic femoral necks, hypoplastic iliac bodies and shallow acetabulae, irregular metaphyseal mineralization and demarcation of the long tubular bones, short metacarpals with widened shafts (I and V), very short and broad phalanges with small, late-ossifying epiphyses and bullet-shaped middle phalanges, and midfacial hypoplasia
  • Genetic determination autosomal recessive
    Function/system disorder osteo-articular
    Type disease
    Mechanism(s)
    Gene mutationChromosome rearrangementEffectComments
    insertion-deletion   unknown do not affect B-cyclin messenger RNA (mRNA) levels but do severely incapacitate ribosomal assembly via defective endonucleolytic cleavage
    Remark(s)
    Genotype/Phenotype correlations the more severe skeletal phenotype caused either by two mutations leading to intermediate-to-severe functional alteration of rRNA cleavage or by compound heterozygosity of the mutations leading to intermediate-to-severe functional alteration, with an allele leading to absence of the respective mRNA