Partial Trisomy 6q is extremely rare. Many affected
infants and children have growth retardation, mental retardation,
craniofacial anomalies, a short, webbed neck, and joint contractures.
Chromosome 6, Trisomy 6q2; Distal Trisomy 6q; Duplication
6q; Partial Distal Duplication 6q.
Extremely rare. Appears to affect males and females
equally. Approximately 30 cases have been reported in the medical
Chromosome 6, partial trisomy 6q is the result
of a balanced translocation in one of the parents. The duplicated portion of
6q2 begins between bands 6q21 and 6q26 and may extend to the end (or
“terminal”) of chromosome 6q (qter).
Craniofacial abnormalities include microcephaly,
an abnormally flat face and occiput, an “almond-shaped,” protruding,
ocular hypertelorism, and/or downwardly slanting palpebral fissures. Affected
individuals may also have a small “bow-shaped” mouth with thin lips,
micrognathia, cleft palate, a large, flat nose, malformed ears, and/or thin,
arched eyebrows. In some cases, the coronal and sagittal craniosynostosis
causing turricephaly has been reported. The neck may be unusually short and
wide with abnormal frontolateral webbing, potentially restricting movement
of the jaw and neck. The hairline may be abnormally low on the back of the
neck (nape). Joint contractures (fingers, wrists, elbows, knees, hips),
causing limitation of movement and abnormal postures, are often associated.
Polysyndactyly, clubhands and/or clubfeet, scoliosis, reduced diameter of
the chest, and widely spaced nipples. Genital abnormalities include, in
affected females, hypoplastic labia, and in affected males, micropenis,
hypospadias, and cryptorchidism. It may also include cardiac, intestinal,
renal, and cerebral abnormalities.
Evaluate cardiac function (clinical,
echocardiography, ECG) and renal function (echography, urea, creatinine,
electrolytes). Anesthesia consultation is indicated to assess the airway and
other medical conditions (especially cardiac).
Careful intraoperative positioning
should be done (vertebral anomalies, joint contractures). Direct
laryngoscopy and tracheal intubation will be difficult because of short and
webbed neck, the presence of micrognathia, a small mouth opening, and
retrognathia. Spontaneous respiration must be maintained until the trachea is intubated and
lung ventilation confirmed. Venous access can be difficult because of limb anomalies.
Perimedullar anesthesia is often contraindicated or difficult because of vertebral and
Prophylactic antibiotics should be as
indicated in cases of cardiac defect. Preserve spontaneous ventilation
before and during laryngoscopy until tracheal intubation is secured. Avoid
anesthetic drugs with marked cardiovascular effects.
Conrad BA, Higgins RR, Pierpont MEM: Duplication 6q22 → qter:
Definition of the phenotype. Am J Med Genet
Dellacasa P: Partial trisomy of the long arm of chromosome 6. A clinical
case. Minerva Pediatr
Erdel M, Duba HC, Verdorfer I, et al: Comparative genomic hybridization
reveals a partial de novo trisomy 6q23-qter in an infant with congenital
malformations: Delineation of the phenotype. Hum Genet