Familial cartilage–hair hypoplasia: prenatal ultrasound features and clinical outcomes in three siblings with identical RMRP variants

Cartilage-hair hypoplasia (CHH) is a rare autosomal recessive skeletal dysplasia. It is often associated with short stature, metaphyseal abnormalities, hair hypoplasia and immune dysfunction. This case describes a pregnant woman in her mid-30s with two previous children diagnosed with CHH with molecular confirmation of two pathogenic variants of the ribonuclease mitochondrial RNA processing gene. The couple is healthy and non-consanguineous. Routine ultrasound examination of the current pregnancy suggested this fetus was also likely to be affected. The couple opted not to perform invasive prenatal diagnosis. Umbilical cord blood was collected at birth for genetic testing, confirming the diagnosis. CHH has a significant impact on the quality of life of those affected. Genetic counselling may help parents understand the disease and its prognosis. Obstetric ultrasound plays an important role in the diagnosis by allowing early detection of suspected cases as well as assessing fetal growth.