A paternally inherited duplication in the Prader-Willi/Angelman syndrome critical region: a case and family study.
A dad-passed 15q11-13 duplication can ride along with autism, so add genetic screening when hypotonia and loose joints show up.
01Research in Context
What this study did
Doctors looked at one girl with autism, low muscle tone, and loose joints. They ran a chromosome test on her and her family.
The test found a tiny extra copy of DNA on chromosome 15. The piece came from Dad and sits in the Prader-Willi/Angelman region.
What they found
The girl met criteria for PDD-NOS and borderline intellectual disability. Dad and her sister carry the same extra piece, yet they show no autism signs.
The extra copy alone does not guarantee autism; other factors likely shape the outcome.
How this fits with other research
Earlier screens saw the same 15q11-q13 area. Gaily et al. (1998) found tetrasomy 15 in classic autism, while Estécio et al. (2002) saw tetrasomy in Brazilian youths with PDDs. All point to this region as dosage-sensitive.
Mertz et al. (2014) looked at the flip side: 15q deletions in Angelman syndrome. Deletion kids had worse language than non-deletion kids. Together the papers show either too much or too little DNA here can disrupt brain development.
Green et al. (1986) first urged chromosome checks for autistic clients with unexplained intellectual disability. This single case keeps that advice alive.
Why it matters
When you see a client with autism plus low tone and loose joints, think about a genetics referral. The 15q region is small and easy to miss. A simple micro-array can rule in or out this duplication. Knowing the result helps families understand risk to future children and guides you toward realistic language and motor goals.
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02At a glance
03Original abstract
The Prader-Willi/Angelman Critical Region (PWACR; Chromosome 15q11-13) is of interest as a potential locus for genes conferring susceptibility to autism spectrum disorders (ASD). This report describes a female proband referred for evaluation of a possible ASD. Genetic analyses indicated that the proband, her father and one of her sisters, carried a paternally derived interstitial duplication involving 15q11-13. The proband showed evidence of ASD (PDD-NOS), borderline mental retardation, mild hypotonia and joint laxity. Her father and her sister were of normal intelligence and neither was thought to have an ASD, although speech/language difficulties and some autistic type behaviours were reported to have been present early in the development of the sister. This is one of the first reports of a child with a paternal duplication and an autism spectrum disorder. More research is required to determine whether paternally derived duplications that involve 15q11-13 are associated with developmental impairments.
Journal of autism and developmental disorders, 2005 · doi:10.1007/s10803-004-1039-1