3-M syndrome: a novel CUL7 mutation associated with respiratory distress and a good response to GH therapy

Abstract

3-M syndrome is a rare autosomal recessive disorder caused by mutations in the CUL7, OBSL1 and CCDC8 genes. It is characterised by growth failure, dysmorphic features and skeletal abnormalities. Data in the literature show variable efficacy of GH in the treatment of short stature. We report four Emirati siblings with the condition. The index case is a 10-year-old boy with characteristic features, including prenatal and postnatal growth failure, a triangular face, a long philtrum, full lips and prominent heels. Genetic testing confirmed a novel mutation (p.val88Ala) in the CUL7 gene. The parents are healthy, first-degree cousins with nine children, of whom two died in the first year of life with respiratory failure. Both had low birth weight and growth retardation. The boy's older sibling reached an adult height of 117 cm (-6.71 SDS). She was never treated with GH. He was started on GH treatment at 7 years of age, when his height was 94 cm (-5.3 SDS). 3-M syndrome should be considered in children with short stature who have associated dysmorphism and skeletal abnormalities. The diagnosis is more likely to occur in families that have a history of consanguinity and more than one affected sibling. Death in early infancy due to respiratory failure is another clue to the diagnosis, which might have a variable phenotype within a family. Genetic testing is important for confirming the diagnosis and for genetic counselling. GH treatment might be beneficial in improving stature in affected children.

Learning points: 3-M syndrome should be considered in families that have more than one sibling with short stature, particularly if there is consanguinity.Syndrome phenotype might be variable within a family with the same mutation.Genetic analysis is helpful in confirming diagnosis in the presence of variable siblings' phenotype.GH treatment might be useful in improving stature in 3-M syndrome.

Figure 1

Family pedigree showing affected siblings. Carrier status in both parents is indicated by a small closed circle inside the circle and square.

Figure 2

Photo of the face of the index case showing (A) his triangular face, upturned nose and full lips, (B) lordosis and (C) the prominent heel of his foot.

Figure 3

Line chart showing height and height SDS. Start of growth hormone (GH) treatment is indicated on the graph.