16p13.11 microdeletion

Inspired by a patient

When only very small numbers of people have been identified, we can’t yet be certain what the full range of possible effects of the microdeletion are. Additionally, the features vary, even between members of the same family. They do not affect everyone and in any individual they can be more or less obvious. The most common features are:  

Delay in learning to sit, move and walk,

Delay in starting to speak and language development,

Children may need support with learning. The amount of support needed by each child will vary, although most benefit from supportive services for special needs

 Increased risk of developing seizures

Microcephaly (a small head)

Are there people with a 16p13.11 microdeletion who have developed normally and have no speech, learning or health difficulties?  

Yes, there are. The 16p13.11 microdeletion can be silent. Some parents of children with a 16p13.11 microdeletion have the same microdeletion but do not have any obvious unusual features or delayed development.  The effect on development, health and behaviour of some genetic disorders ranges from being barely perceptible to being obvious and severe. In this sense they are like infections such as flu that can be mild or serious.

If one person in a family with the 16p13.11 microdeletion is mildly affected, will others in the same family also be mildly affected?

Not necessarily. There is a lot of variation between different members of the same family who have the same microdeletion. We know that if one person is mildly affected or unaffected, others may be more severely and obviously affected…

Delay in starting to speak and language development 

A delay in speech and language is very common, although not universal. Two Unique babies did not cry or vocalise as newborns. In the medical literature many children are described as having speech delay. One adult had some speech difficulties when young and still gets words mixed up sometimes. A 4-year-old has language corresponding to an 18-month old; a 12-year-old has only isolated words; a 19-year-old has echolalia (the repetition of speech just spoken by somebody else in an involuntary and meaningless way); an adult has difficulty in expressive language but another adult is described as ‘very talkative’. 

Increased risk of developing seizures

Seizures (epilepsy) appear to be a common feature for those with a 16p13.11 microdeletion. There have been three large-scale studies of people with epilepsy which have attempted to identify a genetic basis for their epilepsy. These studies have resulted in 36 people with epilepsy being diagnosed with a 16p13.11 microdeletion. A further three people in the medical literature and two at Unique have seizures. There is a wide range in the severity and type of seizures. Two children had West syndrome (also known as infantile spasms affecting children under the age of one year). Generally, seizures appear to be well controlled with medication although one adult in the medical literature has epilepsy that has been resistant to therapy. The 16p13.11 microdeletion is the most common single genetic risk factor for developing seizures identified to date. 

Some babies with a 16p13.11 microdeletion are born with a birth defect. Others are not. Birth defects can affect any organ in the body: there doesn’t seem to be any consistent pattern

Many babies with a 16p13.11 microdeletion are born completely healthy. Others have a birth defect which can be quite minor or more serious. Most of the birth defects reported among babies with 16p13.11 microdeletion have only occurred in just a few babies, so they may be a coincidence, and it is still not clear if all of the birth defects reported here are actually caused by the 16p13.11 microdeletion. However, one common finding is that on investigation, 17 people with the microdeletion 8 have some anomaly of the brain structure that shows on magnetic resonance imaging (MRI). Various anomalies have been detected and there appears to be no consistent feature...

Behavior

In general children with a 16p13.11 microdeletion are happy, kind, affectionate and social. However, they are as vulnerable to frustration as other children with a communication difficulty and a small minority succumb to temper tantrums and aggression. One adult described in the medical literature was very talkative with intermittent verbal aggression and self-mutilation.

Autistic traits or autistic spectrum disorder (ASD) have also been reported in several people with a 16p13.11 microdeletion. A diagnosis of autism can be extremely helpful in accessing services and tailoring the educational and behavioural therapy to meet the specific needs of a child with autism. Two children find socialising difficult, one of whom has been diagnosed with an anxiety disorder. Four children have obsessive compulsive disorder (OCD), an anxiety-related condition in which people experience frequent intrusive and unwelcome obsessional thoughts, often followed by repetitive compulsions, impulses or urges. Sensory issues have also been reported to affect four children. One person has Tourette syndrome (a neurological disorder characterized by repetitive, stereotyped, involuntary movements and vocalisations called tics). One person in the medical literature is described as having psychotic depression (depression accompanied by hallucinations and delusions) which developed after the onset of epilepsy and another has psychosis (a condition that affects a person’s mind and causes changes to the way that they think, feel and behave and can result in an inability to distinguish between reality and imagination) which is controlled with medication…

Adults with 16p13.11 microdeletions

A number of adults have been described in the medical literature and Unique has three adult members with the microdeletion. Many have no developmental delay or health issues. One man discovered he had the 16p13.11 microdeletion when his son was diagnosed. He had learning difficulties and left school early to be a fisherman. A mother, who only discovered her 16p13.11 microdeletion after her son with learning difficulties was diagnosed, had a similar facial appearance to her son but had no other unusual features and did not have delayed development. Two other mothers where the microdeletion was discovered after their children were diagnosed, always struggled in school.

http://www.rarechromo.org/information/Chromosome%2016/16p13.11%20microdeletions%20FTNW.pdf