Recombinant Chromosome 8 Syndrome

At a glance

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.

Synonyms

San Luis Valley Syndrome; Rec 8 Syndrome; SLV Syndrome.

History

First described by A. Fujimoto in 1975.

Incidence

Rare; mostly seen in Hispanic children born in the southwestern United States.

Genetic inheritance

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. Common ancestor in a village in northeastern New Mexico in late 1800s.

Pathophysiology

Recombinant 8 genotype has a duplication of 8q22.1-qter and deletion of 8pter-p23.1. The rec8 phenotype consists of a characteristic set of minor facial anomalies, cardiovascular and other major malformations, and moderate to severe mental retardation.

Diagnosis

Clinical based on the characteristic facies and the presence of mental retardation, cardiac, and urogenital malformations. Chromosomal study.

Clinical aspects

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). Mild-to-severe cognitive impairment with preservation in the social/adaptive arenas. No increased morbidity and mortality following cardiac surgery.

Precautions before anesthesia

Full cardiac evaluation including ECG, chest radiograph, echocardiogram, and cardiac catheterization must be obtained prior to surgery 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, electroencephalogram (EEG), computed tomography (CT), magnetic resonance imaging (MRI).

Anesthetic considerations

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 ...