Case report

The patient is the first and only child of healthy, non-consanguineous parents. During routine ultrasound scanning, the fetus was noted to have extremely short limbs and a tentative diagnosis of achrondroplasia was made. The pregnancy was otherwise uncomplicated. The baby was delivered at 40 weeks' gestation by emergency caesarian section because of breech presentation. Birth weight was 2460 g and length 44 cm (both below the 3rd centile). During infancy and early childhood, her height remained well below the 0.4th centile.

Examination showed a small baby with midface hypoplasia and a small, slightly upturned nose. With increasing age, the prominent forehead, saddle shaped nose, and midface hypoplasia became more obvious. There was rhizomelic and mesomelic shortening of her upper and lower limbs (fig 1). She was noted to have short, broad hands and feet with deep palmar creases, short toes, and dimples in the elbows and knees. In addition, she had marked generalised joint laxity except at the elbows where extension was limited. A skeletal survey at 5 months was not diagnostic, but achondroplasia was excluded.

Chromosomal analysis was normal (46,XX).

At 4 months of age, she was noted to have an eczematous skin rash, and there followed several hospital admissions for recurrent chest infections; investigations showed hypogammaglobulinaemia. Both the skin rash and the hypogammaglobulinaemia gradually normalised, effectively excluding a diagnosis of a short limbed dwarfism syndrome in association with immunodeficiency.

Despite a dysplastic (but not dislocated) left hip, crawling and walking were not delayed; however at 2 years of age she developed a waddling gait, and at 2 years 5 months a dislocated left hip was …