Endocrine Abstracts (2017) 49 EP812 | DOI: 10.1530/endoabs.49.EP812

Microduplication of 15q26.3 not including IGF1R as a novel genetic cause of infantile overgrowth

Jean De Schepper1,2, Denis Libeert2 & Bert Callewaert2

1UZ Brussel, Brussels, Belgium; 2UZ Gent, Ghent, Belgium.

Introduction: Recently, a microduplication of 15q26.3 not including IGF1R was reported in subjects of two families with overgrowth and variable intellectual disability (Leffler M. et al., Eur J Med Gen, 2016).

Aim: To report the clinical findings in a third case with overgrowth related to a small microduplication of 15q26.3 not including the IGF1R region.

Methods: Comparative genome hybridization was done using an Agilent 180k microarray platform.

Results: Accelerated linear growth was observed after the first 3 months with a normal weight increase in a female patient, born at 36 weeks of gestation by normal delivery. At birth weight was 3200 g (>97th centile), length 52 cm (>97th centile) and head circumference (HC) 35.5 cm (97th centile). Mother’s and father’s height was 182 cm. She had transient feeding problems, necessitating nasogastric feeding in the first week of life. She presented with delayed motor development. Teeth erupted prematurely. At the age of 2 years, her length was 96 cm (> 97th centile), weight 16 kg (97th centile), HC 51 cm (97th centile) and armspan 96 cm. She showed a high forehead, mild synophris, epicanthal folds, deep-set eyes, a flat nasal bridge, mid face flattening, a prominent chin, and tapering fingers. Ultrasound of the abdomen and heart were normal. Bone maturation and serum IGF-1 were normal. ArrayCGH analysis showed a de novo 1.6 Mb duplication of 15q26.3 (arr 15q26.3q26.3 (98386658 99753407)x3). Speech delay and mild coordination and motor problems were noted later on, whereas height and weight progressed normally but above the 97th percentile. At the age of 4 year, mitral valve insufficiency developed, necessitating a surgical repair.

Conclusions: The previous and this case report highlight the possible involvement of the distal region of 15q in infantile overgrowth, independent of IFGR1 duplication. Delayed speech development, tall stature and macrocephaly with a prominent chin appear constant findings, while cardiac manifestations may be variably present.

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