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While several case reports describe partial trisomy 12qter, reports of interstitial 12q duplications are extremely rare. We present here the clinical findings in a female infant with mosaicism for a duplication of chromosome 12q13.3→12q21.2 accompanied by a pericentric inversion (12)(p13.3q21.2). No other cases with an interstitial duplication for this region have been reported. The female infant has several dysmorphic anomalies but has no symptoms associated with the clinically distinguishable syndrome of 12q duplication.1 Since the duplication is maternally isodisomic, the rearrangement is most likely of postzygotic origin.
CASE REPORT
The index patient, a female, is the first child of healthy, non-consanguineous parents with normal family histories. At her birth, the father was 39 years and the mother 35 years old.
Pregnancy and term delivery were normal. Birth weight was 3200 g (75th centile), length 50 cm (50th centile), and OFC 32.5 cm (3rd centile is 33 cm). In addition to the microcephaly, a distinct craniofacial appearance was noted, including antimongoloid position of both eyes with shallow orbits and proptosis, periorbital oedema, trigonocephaly, and large, everted, and poorly lobulated ears (fig 1). Additional findings were accessory nipple on the right, deep sacral sulcus, hypertrophic clitoris with otherwise normal external genitalia, and bilateral metatarsus adductus. No internal malformations were present with normal cardiac and renal imaging. No perinatal or postnatal problems were noted. Now, at the age of 11 months, psychomotor development is mildly retarded (developmental age of 10 months on the Bayley Developmental scale). Weight is 8.7 kg (25th centile), length 75 cm (75th centile), and OFC 41.8 cm (3rd centile is 43 cm).
Cytogenetic studies were performed using PHA stimulated lymphocytes according to standard cytogenetic procedures. High …