Editor—Hypomelanosis of Ito (HI) (MIM 146150) is an aetiologically heterogeneous physical finding characterised by a swirling pattern of hypopigmentation of the skin, typically distributed along the lines of Blaschko, reflecting pigmentary mosaicism. Chromosomal abnormalities are common and very heterogeneous. They include X;autosomal translocations and mosaicism of aneuploidy, segmental trisomies, or monosomies.1-5 As HI is not a specific disorder, it has also been referred to as pigmentary mosaicism.6 This report adds a further chromosomal anomaly which has not been described in pigmentary mosaicism previously.

The proband was the first son born to a 29 year old mother and a 30 year old father. There was no family history of recurrent abortions, consanguinity, or mental retardation. He was born by caesarian section at term after an uncomplicated pregnancy with a weight of 3560 g (50th centile), a length of 50 cm (50th centile), and an occipitofrontal circumference (OFC) of 32 cm (<3rd centile). Apgar scores were 8, 9, and 10. No complications were reported in the perinatal period. Despite delayed psychomotor milestones (sitting at 9 months, walking at 2 years, first words at 3 years), the first evaluation was only done at the age of 5 years. At the age of 10 years he was referred to our endocrinological outpatient clinic because of cryptorchidism and glandular hypospadias. At this time he was found to be a shy and uncommunicative boy. He showed moderate mental retardation and attended a school for handicapped children. He had a height of 1.3 m (3rd centile), a weight of 26 kg (3rd centile), and an OFC of 50 cm (<3rd centile). On physical examination, mild facial asymmetry, epicanthic folds, a broad nose with a broad nasal tip, retrognathia, dysplastic ears, and a low set posterior hair line were noted (fig 1). Areas of …