Microcephalic Osteodysplastic Primordial Dwarfism, Type I

Also known as: Taybi–Linder syndrome


Transcript: U4atac small nuclear RNA

Clinical Characteristics

  • Marked intrauterine and postnatal growth retardation
  • Microcephaly
  • Skeletal abnormalities:
    • Vertebral and pelvic anomalies
    • Short bowed long bones
    • Wide metaphyses
    • Delayed epiphyseal maturation
  • Brain malformations:
    • Agenesis of the corpus callosum or cerebellar vermis
    • Lissencephaly or other gyral abnormalities
    • Hypoplastic frontal lobes
  • Dysmorphic facial features:
    • Prominent nose with a downturned tip
    • Sloping forehead
    • Protruding eyes
    • Low-set ears
    • Micrognathia
  • Sparse hair and dry skin
  • Developmental delay
  • Death typically occurs in the first year of life

Inheritance pattern: Autosomal recessive

What Can Be Learned From This Test

Testing is performed by sequencing the entire RNU4ATAC gene and surrounding regions. This will detect point mutations, small deletions and small insertions. It will not detect a whole gene deletion or duplication.

RNU4ATAC is the only gene known to be associated with microcephalic osteodysplastic primordial dwarfism, type I (MOPD I). A negative test does not rule out a diagnosis of MOPD I since a mutation could be in a region not sequenced or in another gene.

Sample Requirements

Draw 2ml–4ml of blood in EDTA/purple-top tube (minimum of 1ml–2ml for infants).

Turnaround time: 10-14 business days

CPT Codes and Cost

Full Gene Sequencing

  • Code: 81479
  • Cost: $225

Known Variant Testing

  • Code: 81479
  • Cost: $225

Additional Information