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GENATLAS PHENOTYPE
last update : 31-08-2010
Symbol CHH
Location 9p13.3
Name cartilage hair hypoplasia
Other name(s) metaphyseal chondrodysplasia, McKusick type
Corresponding gene RMRP
Main clinical features
  • metaphyseal chondrodysplasia, dwarfism, bowing of the long bone, with neutropenia, defective immunity, hypoplastic anemia, and Hirschsprung disease and increased apoptosis of T cell with altered expression of FAS and FAS1, with great clinical variability
  • hair fine, sparse and light-colored, with an abnormally small caliber on microscopic examination, major immunologic defect that was manifested, for example, as an unusual susceptibility to chickenpox (cases of fatal varicella pneumonia )
  • substantially high risk of non-Hodgkin lymphoma and basal cell carcinoma at young age
  • Genetic determination autosomal recessive
    Related entries . including metaphyseal dysplasia without hypotrichosis or immunodeficiency, OMIM 250460, (absence of extraskeletal manifestation ) . including metaphyseal chondrodysplasia Spahr type (OMIM 250400)
    Function/system disorder osteo-articular
    Type disease
    Mechanism(s)
    Gene mutationChromosome rearrangementEffectComments
    various types     compound heterozygotes for null/leaky or homozygotes leaky/leaky mutations, lead to decreased cell growth by impairing ribosomal assembly and by altering cyclin-dependent cell cycle regulation
    Remark(s)
    Genotype/Phenotype correlations the milder skeletal phenotypes are caused either by two mutations leading to mild-to-intermediate functional alteration of mRNA and rRNA cleavage or by compound heterozygosity with one of the mutations leading to mild-to-intermediate functional alteration and one allele reducing the transcription level by alterations within the distance between the TATA box and the transcription start site