What's behind this baby's overgrown tongue?

A 13-month-old baby is able to smile for the first time after undergoing surgery to reduce the size of her abnormally large tongue.

Layla King from St Louis, Missouri, US, was diagnosed with Beckwith–Wiedemann syndrome — a congenital overgrowth disorder — in utero during a 30-week scan (right), UK newspaper the Mirror reported.

The genetic condition, which affects one in 13,700 newborns worldwide, can cause macroglossia, pre- and postnatal overgrowth and abdominal wall defects.