Chromosomal disorder found in individuals of Hispanic
descent with ancestry from the San Luis Valley in the Southwest of the
United States. The association of mental retardation, congenital heart defects,
seizures, a characteristic facial appearance, and urogenital anomalies
characterizes the syndrome.
San Luis Valley Syndrome; Rec 8 Syndrome.
First described by A. Fujimoto in 1975.
Rare; mostly seen in Hispanic children born in the
southwestern United States.
Because of an unbalanced recombinant
chromosome 8 with partial duplication of the long arm of the maternal
pericentric inversion (inv 8p23.1q22.1). There is an approximately 6%
risk that an inv(8) carrier will have an offspring with Recombinant
Chromosome 8 Syndrome.
Recombinant 8 genotype has a duplication
8q(q22->qter) and deficiency 8p(p23->pter), resulting in rec8
(8qter->8q22.1:8p23.1->8qter). The rec8 phenotype consists of a
characteristic set of minor facial anomalies, cardiovascular and other major
malformations, and moderate to severe mental retardation.
Clinical based on the characteristic facies and the presence of
mental retardation, cardiac, and urogenital malformations. Chromosomal
Features involve head (brachycephaly, wide face,
midface hypoplasia, infraorbital creases, hypertelorism, anteverted nares,
thin upper lip, thick lower lip, downturn mouth, gingival hyperplasia,
micrognathia, strabismus, nystagmus, low-set ears, hearing loss with
frequent otitis media), heart (conotruncal defect and tetralogy of Fallot are
most common), central nervous system (CNS) (moderate to severe mental retardation, seizure,
abnormal muscle tone with either hypertonia or hypotonia, scoliosis common from
neuromuscular origin), urogenital system (cryptorchidism, hypoplastic scrotum, other urinary
tract anomalies, impairment of renal function).
Full cardiac evaluation including
ECG, chest radiograph, echocardiogram, and cardiac catheterization must be
obtained because it is the major cause of mortality. Depending on the severity of the facial
a careful evaluation of the airway must be conducted (clinical, radiographic). Renal
function tests must include renal ultrasonography, intravenous pyelogram, routine
electrolytes, urea, and creatinine. Neurological test includes clinical, EEG, CT, and MRI.
Techniques should be tailored to the
cardiac defect present and the procedure planned. Measures to prevent air embolism must be
taken. Adequate intravascular hydration must be ensured. The presence of macroglossia and micrognathia may
contribute to difficult laryngoscopy and tracheal intubation. A laryngeal mask should
always be available. Positioning may be difficult if contracture occurred from hypertonia.
The risk of pressure necrosis must be considered.
May consider avoiding suxamethonium
if there is evidence of delayed myelination in CNS. Consider interaction
between antiepileptic medication and anesthetic drugs. Endocarditis
prophylaxis as indicated. Avoid muscle relaxants until airway is secured.
Fujimoto A, Wilson MG, Towner JW: Familial inversion of chromosome no. 8:
An affected child and a carrier fetus. Humangenetik
Gelb B, Towbin J, McCabe E, et al: San Luis Valley recombinant chromosome 8
and tetralogy of Fallot: A review of chromosome 8 anomalies and congenital
heart disease. Am J Med Genet 40:471, 1991....