(Monosomy 1p36)

Estimated prevalence around 1/5,000 . Microdeletional syndrome due to the deletion of part of the terminal end of the short arm  of one of the two chromosomes 6. The deletion is variable in size and is usually pure and terminal but can be interstitial or result from an unbalanced translocation and is then  associated with partial trisomy of another chromosome. This monosomy is considered as a syndrome of contiguous genes without a well-established genotype-phenotype correlation, which combines a psychomotor retardation, seizures, behavior disorders, microcephaly with dysmorphism and growth retardation.

Clinical details:

• dysmorphic features: brachycephaly, prominent forehead, sunken eyes, horizontal eyebrows and short palpebral fissures, epicanthus, flat nose, dysplastic ears and pointed chin. Wide fontanel taking a long time to close
• severe psychomotor retardation with moderate to profound hypotonia during the first year of life; mental retardation, unstable walking and limited speech development; occasional aggressive behavior with temper tantrums and self-harm
• epilepsy (60 %): onset in general within 6 months of age; infantile spasms or  generalized tonicoclonic or clonic seizures, becoming resistant to treatment in 10 to 50 % of the cases
• heart disease (50 %): patent ductus arteriosus, ASD, Fallot's tetralogy, a few cases of very early onset dilated cardiomyopathy
• other: brachydactyly, camptodactyly, small feet, cleft / lip palate
• feeding difficulties in early childhood sometimes followed with hyperphagia with obesity similar to the Willi-Prader syndrome
• occasional: hypothyroidism, precocious puberty

Anesthetic implications: 

echocardiography, mental retardation, epilepsy, sometimes obesity

References : 

-         Afenjar A, Burglen L. 
Nouveaux syndrome microdélétionnels. 
Médecine Thérapeutique Pédiatrie; 2008 : 11 : 224-9.

Updated: August 2019