ABCC8 and KCNJ11 molecular spectrum of 109 patients with diazoxide-unresponsive congenital hyperinsulinism.
BACKGROUND
Congenital hyperinsulinism (CHI) is characterised by an over secretion of insulin by the pancreatic β-cells. This condition is mostly caused by mutations in ABCC8 or KCNJ11 genes encoding the SUR1 and KIR6.2 subunits of the ATP-sensitive potassium (K(ATP)) channel. CHI patients are classified according to their responsiveness to diazoxide and to their histopathological diagnosis (either focal, diffuse or atypical forms). Here, we raise the benefits/limits of the genetic diagnosis in the clinical management of CHI patients.


METHODS
ABCC8/KCNJ11 mutational spectrum was established in 109 diazoxide-unresponsive CHI patients for whom an appropriate clinical management is essential to prevent brain damage. Relationships between genotype and radiopathological diagnosis were analysed.


RESULTS
ABCC8 or KCNJ11 defects were found in 82% of the CHI cases. All patients with a focal form were associated with a single K(ATP) channel molecular event. In contrast, patients with diffuse forms were genetically more heterogeneous: 47% were associated with recessively inherited mutations, 34% carried a single heterozygous mutation and 19% had no mutation. There appeared to be a predominance of paternally inherited mutations in patients diagnosed with a diffuse form and carrying a sole K(ATP) channel mutation.


CONCLUSIONS
The identification of recessively inherited mutations related to severe and diffuse forms of CHI provides an informative genetic diagnosis and allows prenatal diagnosis. In contrast, in patients carrying a single K(ATP) channel mutation, genetic analysis should be confronted with the PET imaging to categorise patients as focal or diffuse forms in order to get the appropriate therapeutic management.
Bellanné-Chantelot
C
C
Centre de Génétique Moléculaire et Chromosomique, Groupe Hospitalier Pitié Salpêtrière, 47-83 bd de l'Hôpital, 75651 Paris Cedex 13, France. christine.bellanne-chantelot@psl.aphp.fr
Saint-Martin
C
C
Ribeiro
M-J
MJ
Vaury
C
C
Verkarre
V
V
Arnoux
J-B
JB
Valayannopoulos
V
V
Gobrecht
S
S
Sempoux
C
C
Rahier
J
J
Fournet
J-C
JC
Jaubert
F
F
Aigrain
Y
Y
Nihoul-Fékété
C
C
de Lonlay
P
P
D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D044903:Congenital Hyperinsulinism / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics*; D004252:DNA Mutational Analysis; D003981:Diazoxide / Q000627:therapeutic use; D004351:Drug Resistance; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009154:Mutation; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics*; D011955:Receptors, Drug / Q000235:genetics*; D064233:Sulfonylurea Receptors; D014665:Vasodilator Agents / Q000627:therapeutic use; D000099161:Kcnj11 Channel
D018528:ATP-Binding Cassette Transporters; D003981:Diazoxide; D024661:Potassium Channels, Inwardly Rectifying; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; D014665:Vasodilator Agents; D000099161:Kcnj11 Channel; C577507:ABCC8 protein, human