Recombinant chromosome 8 syndrome
Alternate names[edit | edit source]
Rec8 syndrome; San Luis Valley recombinant chromosome 8 syndrome; San Luis Valley syndrome
Definition[edit | edit source]
Recombinant chromosome 8 syndrome is a condition that involves heart and urinary tract abnormalities, moderate to severe intellectual disability, and a distinctive facial appearance. Many children with recombinant chromosome 8 syndrome do not survive past early childhood, usually due to complications related to their heart abnormalities.
Epidemiology[edit | edit source]
- Recombinant 8 syndrome is a rare condition; its exact incidence is unknown.
- Most people with this condition are descended from a Hispanic population originating in the San Luis Valley area of southern Colorado and northern New Mexico.
- Recombinant 8 syndrome is also called San Luis Valley syndrome.
- Only a few cases outside this population have been found.
Cause[edit | edit source]
- Recombinant 8 syndrome is caused by a rearrangement of chromosome 8 that results in a deletion of a piece of the short (p) arm and a duplication of a piece of the long (q) arm.
- The deletion and duplication result in the recombinant 8 chromosome.
- The signs and symptoms of recombinant 8 syndrome are related to the loss and addition of genetic material on these regions of chromosome 8.
- Researchers are working to determine which genes are involved in the deletion and duplication on chromosome 8.
Inheritance[edit | edit source]
- This condition is inherited in an autosomal dominant pattern, which means one copy of the recombinant chromosome 8 in each cell is sufficient to cause the disorder.
- Most people with recombinant 8 syndrome have at least one parent with a change in chromosome 8 called an inversion.
- An inversion involves the breakage of a chromosome in two places; the resulting piece of DNA is reversed and reinserted into the chromosome.
- Genetic material is typically not lost as a result of this inversion in chromosome 8, so people usually do not have any related health problems.
- However, genetic material can be lost or duplicated when inversions are being passed to the next generation.
- People with this chromosome 8 inversion are at of risk having a child with recombinant 8 syndrome.
Signs and symptoms[edit | edit source]
- The characteristic facial features include a wide, square face; a thin upper lip; a downturned mouth; a small chin (micrognathia); wide-set eyes (hypertelorism); and low-set or unusually shaped ears.
- People with recombinant 8 syndrome may have overgrowth of the gums (gingival hyperplasia) and abnormal tooth development. Males with this condition frequently have undescended testes (cryptorchidism).
- Some affected individuals have recurrent ear infections (otitis media) or hearing loss.
- Many children with recombinant 8 syndrome do not survive past early childhood, usually due to complications related to their heart abnormalities.
Clinical presentation[edit | edit source]
For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms
- Abnormality of the dentition(Abnormal dentition)
- Anteverted nares(Nasal tip, upturned)
- Cryptorchidism(Undescended testes)
- Deep plantar creases(Deep wrinkles in soles of feet)
- Downturned corners of mouth(Downturned corners of the mouth)
- Global developmental delay
- Hypertelorism(Wide-set eyes)
- Intellectual disability(Mental deficiency)
- Large face(Big face)
- Low posterior hairline(Low hairline at back of neck)
- Micrognathia(Little lower jaw)
- Redundant skin(Loose redundant skin)
30%-79% of people have these symptoms
- Abnormal oral frenulum morphology
- Abnormality of the kidney(Abnormal kidney)
- Atrial septal defect(An opening in the wall separating the top two chambers of the heart)
- Bilateral single transverse palmar creases
- Camptodactyly of finger(Permanent flexion of the finger)
- Chronic otitis media(Chronic infections of the middle ear)
- Clinodactyly of the 5th finger(Permanent curving of the pinkie finger)
- Depressed nasal bridge(Depressed bridge of nose)
- Gingival overgrowth(Gum enlargement)
- Hearing impairment(Deafness)
- Low-set ears(Low set ears)
- Patellar aplasia(Absent kneecap)
- Patent ductus arteriosus
- Pectus excavatum(Funnel chest)
- Pulmonary artery stenosis(Narrowing of lung artery)
- Scoliosis
- Scrotal hypoplasia(Smaller than typical growth of scrotum)
- Seizure
- Spasticity(Involuntary muscle stiffness, contraction, or spasm)
- Tetralogy of Fallot
- Thick vermilion border(Full lips)
- Ventricular septal defect(Hole in heart wall separating two lower heart chambers)
5%-29% of people have these symptoms
- Abnormality of the anus
- Abnormality of vision(Abnormality of sight)
- Cleft palate(Cleft roof of mouth)
- Cleft upper lip(Harelip)
Diagnosis[edit | edit source]
Postnatal chromosomal microarray and other studies identified a de novo derivative chromosome 8. For fetal anomalies, detailed genetic studies may be required. Brain MR revealed multiple abnormalities primarily affecting midline structures, including commissural dysgenesis, vermian and brainstem hypoplasia/dysplasia, an interhypothalamic adhesion, and an epidermoid between the frontal lobes that enlarged over time. Spine MR demonstrated hypoplastic C1 and C2 posterior elements, scoliosis, and a borderline low conus medullaris position.
Treatment[edit | edit source]
NIH genetic and rare disease info[edit source]
Recombinant chromosome 8 syndrome is a rare disease.
Recombinant chromosome 8 syndrome Resources | ||
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