A unique case of a patient with partial trisomy 22 and lipodystrophy: is it a new syndrome due to an IGF-IR mutation?
A newborn male presented with intestinal malrotation, facial anomalies, hypertrichosis, hypertrophic, hyperpigmented nipples and enlarged genitals with a hyperpigmented scrotum. In addition, the patient displayed a marked lipodystrophy of trunk and limbs. His karyotype demonstrated a small supernumerary NOR-positive marker chromosome that was subsequently identified as del(22)(q12->qter). This extra structurally abnormal chromosome probably derives from a maternal balanced translocation, which was found by karyotype analysis of the mother. The patient's growth hormone (GH) serum levels were elevated, whereas serum insulin-like growth factor 1 (IGF-I) was almost undetectable. Molecular genetic analysis of the IGF-I and type 1 IGF receptor (IGF-IR) genes revealed a heterozygous mutation within exon 21 of the IGF-IR (Pro1257Ser). Findings in our patient correlate to a large extent with partial trisomy 22. Phenotypic variation from classical partial trisomy 22 syndrome may lie within the variability of this syndrome, originate from disturbances within the GH-IGF/IGF-IR axis or, alternatively, reflect the pathogenesis of a new syndrome due to the synergistical impact of the combination of the genetic aberrations. Additional studies are necessary to confirm or refute this hypothesis.
Caglayan
A O
AO
Kayseri Education and Research Hospital, Department of Medical Genetics, Kayseri, Turkey. okaycaglayan@yahoo.com
Klammt
J
J
Kiess
W
W
Hatipoglu
N
N
Pfäffle
R
R
Kurtoglu
S
S
Saatci
C
C
Dundar
M
M
D000015:Abnormalities, Multiple / Q000235:genetics*; D002892:Chromosomes, Human, Pair 22; D006801:Humans; D007231:Infant, Newborn; D008060:Lipodystrophy / Q000235:genetics*; D008297:Male; D009154:Mutation; D017526:Receptor, IGF Type 1 / Q000235:genetics*; D013577:Syndrome; D014314:Trisomy
D017526:Receptor, IGF Type 1