NEW INSIGHTS INTO THE PHENOTYPES OF 6Q DELETIONS

Deletions of chromosome 6q are rare, We report 3 new patients with 6q deletions. Case 1 is a male with an interstitial deletion [del(6)(q13q 14.2)], hypotonia, speech delays, and minor anomalies. Case 2 is a mal e with an interstitial deletion [del(6) (q16.2q22.32)] and malformatio ns, including truncus arteriosus and bilateral oligodactyly. Case 3 is a male with a terminal deletion [del(6)(q25.2)] with retinal pits, hy drocephalus, atrioventricular canal, and hydronephrosis. The findings in our patients and those from 57 previously reported cases demonstrat ed 3 phenotypic groups associated with 6q deletions. Group A [del(6)(q 11-q16)] had a high incidence of hernias, upslanting palpebral fissure s, and thin lips with lower frequency of microcephaly, micrognathia, a nd heart malformations. Group B [del(6)(q15-q25)] was associated with increased intrauterine growth retardation, abnormal respiration, hyper telorism, and upper limb malformations. Group C [del(6)(q25-qter)] was associated with retinal abnormalities, cleft palate, and genital hypo plasia. The only universal finding among all patients with 6q deletion s was mental retardation. Other findings common to all 3 groups includ ed ear anomalies (90%), hypotonia (82%), and postnatal growth retardat ion (68%). Am. J. Med. Genet. 70:377-386, 1997. (C) 1997 Wiley-Liss, I nc.