What are the first signs that a baby or child has the disorder?
The first signs can be incredibly diverse. Out of a group of 14 babies, five seemed fine at birth but concern grew later about their development: they failed to track visually, to watch their mother while feeding or their rate of development was slow. One baby seemed to progress as expected until developing a type of seizure at three months; another repeatedly failed hearing tests.
In nine babies there were signs immediately after birth of something wrong, varying from a weak cry, feeding difficulties and unusual facial features (twice thought to suggest Down’s syndrome) to a small head, hernias in the groin and at the navel, a floppy larynx, heart problems, cataracts and seizures. Although a low muscle tone (floppiness) is usually characteristic of newborn babies with Kleefstra syndrome, this may not be obvious: in four babies, no floppiness was observed.
For most of the 13 mothers who told Unique about their pregnancy, everything went normally. Three mothers noticed less fetal movement than they expected and one noticed more. One mother had an excess of amniotic fluid (polyhydramnios). Serum screening showed a very high risk of Down syndrome in one mother and later ultrasounds (including 3D ultrasound) showed a small baby who often stuck her tongue out; ultrasound showed small arms and legs in another baby. Most babies were born at or near their due date but five were born slightly early, at 34, 36 and 37 weeks. One baby was induced at 34 weeks when amniotic fluid levels fell.
There isn’t such a thing as a typical newborn baby with Kleefstra syndrome. Unique babies vary greatly in birth weight – between 4.563 kg (10lb 1oz) and 2.6 kg (5lb 12oz) at term; a normal or high birth weight is most typical. Some babies are well and thrive, while others are unusually quiet and passive and a few need to spend time in special care. More babies are jaundiced than you would expect. Early feeding difficulties are common and so is silent reflux – where milk returns from the stomach up the food passage. Most babies with feeding difficulties only need help (tube feeding) for a short time. Apart from these common difficulties of newborns, most babies with the syndrome have reasonable Apgar scores (a measure of well being at birth, scored from 0-10) and are quite well after birth and are able to go home after delivery at the normal time. A few babies have more obvious, specific health concerns. In the Unique sample, these included cataracts, hernias, a heart murmur, a rapid heartbeat or spells of turning blue  or stopping breathing. One baby developed a serious chest infection at birth. One needed extra oxygen and had a floppy larynx, lung disease, kidney reflux and other difficulties. A baby’s cry may signal something unusual – sounding surprisingly weak or grunting. Two babies were found at birth to have a hearing impairment.

Many cases have been reported where a person has been diagnosed in their mid-teens or even in adulthood.  It's expected that this trend will continue as undiagnosed patients are re-checked.

Information reproduced with permission, from Unique's Kleefstra syndrome leaflet.

Additional information