Recombinant Chromosome 8 Syndrome

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 study.

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 anomalies, 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.