Long-term follow-up of growth and puberty in 3-M syndrome: effects of growth hormone therapy and response variability

Abstract

Purpose 3-M syndrome is a rare autosomal recessive growth disorder characterised by severe prenatal and postnatal growth retardation, resulting from mutations in the CUL7, OBSL1, or CCDC8 genes. This study aimed to assess the effects of recom-binant human growth hormone (rhGH) therapy in individuals with 3-M syndrome. Methods A retrospective analysis was conducted on 24 patients (19 males and 5 females) from 16 unrelated families, all with clinically and genetically confirmed diagnoses of 3-M syndrome. Growth patterns and pubertal development were evaluated. Results The median age of the patients was 6.8 years (0.5-21.2). Thirteen families were consanguineous. Median birth weight SDS was -3.8 (-6.3 to -1.4), with all patients born small for gestational age (SGA), except for one patient. All indi-viduals presented with marked growth retardation, with a median height SDS of -4.1 (-7.9 to -2.7). Dysmorphic features characteristic of 3-M syndrome and delayed bone age were observed in all patients. Genetic testing identified pathogenic or likely pathogenic variants in CUL7 in 4 families (25%) and in OBSL1 in the remaining 75%. The rhGH therapy was initiated in 13 patients, with a median starting age of 7.5 years (2.4-13.1) and treatment duration ranging from 1 to 7 years. The overall median change in height SDS was +0.3 (-0.8 to +2.3), reflecting variability in response among patients receiving treatment. A favorable response was observed in 7 out of 13 patients (54%). Pubertal arrest was noted in seven male patients, while two female siblings and one male patient experienced rapidly progressive puberty. Conclusion 3-M syndrome should be included in the differential diagnosis of individuals presenting with severe prenatal and postnatal growth retardation. The rhGH therapy may offer benefit in some cases, although response is variable. Pubertal arrest can occur in males with 3-M syndrome.