Multiple congenital abnormalities and/or mental retardation (MCAMR) or developmental delay;
severe speech delay
Phelan-McDermid Syndrome
Mikrodeletion 22q13.3
Clinical Features
Newborns with Phelan-McDermid Syndrome show a severe muscular hypotonia followed by speech delay and autistic behavior in childhood.
Features (in > 75% of patients)
• Severe muscular hypotonia
• Distinct speech delay or absence of speech
• Developmental delay
• Behavioural abnormalities (autism)
• Reduced sense of pain
• Unspecific dysmorphic features
(dysplastic ears, long eyelashes, large hands, hypoplastic / dysplastic toe nails
Dysmorphic features vary depending on the size of the deletion.
Genetic Information
Patients with Phelan-McDermid Syndrome show a deletion in the terminal band of chromosome 22 (22q13.3). The deletion size varies from 160 Kb to 9 Mb. The minimal critical region maps distal to ARSA. The SHANK3 gene (or ProSAP2) is involved in all deletions. This gene regulates the structural organization of dendrites and is involved in the formation of neuroligines.
Diagnostic
Indication
Method
Karyotyping
FISH or MLPA
Array CGH
Sample Requirement
2 - 5 ml of heparinised blood
2 - 4 ml of EDTA blood
Duration
1 - 2 weeks