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.