Table 2.

Disorders to Consider in the Differential Diagnosis of KCNK9 Imprinting Syndrome

DisorderGenetic MechanismMOIClinical Features of Differential Diagnosis Disorder
Overlapping w/KCNK9 imprinting syndromeDistinguishing from KCNK9 imprinting syndrome
Congenital myotonic dystrophy type 1 >1000 CTG trinucleotide repeat expansion in DMPK 1AD
  • Hypotonia & severe generalized weakness at birth
  • Intellectual disability
  • Usually no cleft palate
Prader-Willi syndrome (PWS)Abnormal parent-specific imprinting w/in the Prader-Willi critical regionSee footnote 2.
  • Severe hypotonia & feeding difficulties in early infancy
  • Delayed motor milestones & language development; some degree of cognitive impairment in all persons
  • Hypotonia & feeding problems resolve more quickly.
  • Usually no cleft palate
22q11.2 deletion syndrome Deletion of genes w/in the DiGeorge chromosome regionAD
  • Palatal abnormalities
  • Characteristic facial features
  • Learning difficulties
  • Immune deficiency
  • Hypocalcemia w/significant feeding & swallowing problems
  • Initial hypotonia less severe
  • Presence of heart defects
1.

Redman et al [1993] reported a few individuals with congenital myotonic dystrophy type 1 with repeats between 730 and 1000.

2.

PWS is caused by lack of expression of the paternally derived PWS/AS region of chromosome 15q11.2-q13 by one of several genetic mechanisms.

From: KCNK9 Imprinting Syndrome

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