Atypical amyoplasia congenita in an infant with Leigh syndrome: A mitochondrial cause of severe contractures?

Diagnostic workup in children with arthrogryposis: description of practices from a single reference centre, comparison with literature and suggestion of recommendations

INTRODUCTION

Arthrogryposis multiplex congenita (AMC) refers to a clinical presentation of congenital contractures involving two or more body areas. More than 400 distinct conditions may lead to AMC, making the aetiological diagnosis challenging. The objective of this work was to set up evidence-based recommendations for the diagnosis of AMC by taking advantage of both data from our nation-wide cohort of children with AMC and from the literature.

MATERIAL AND METHODS

We conducted a retrospective single-centre observational study. Patients had been evaluated at least once at a paediatric age in the AMC clinic of Grenoble University Hospital between 2007 and 2019. After gathering data about their diagnostic procedure, a literature review was performed for each paraclinical investigation to discuss their relevance.

RESULTS

One hundred and twenty-five patients were included, 43% had Amyoplasia, 27% had distal arthrogryposis and 30% had other forms. A definitive aetiological diagnosis was available for 66% of cases. We recommend a two-time diagnostic process: first, non-invasive investigations that aim at classifying patients into one of the three groups, and second, selected investigations targeting a subset of patients.

CONCLUSION

The aetiological management for patients with AMC remains arduous. This process will be facilitated by the increasing use of next-generation sequencing combined with detailed phenotyping. Invasive investigations should be avoided because of their limited yield.

Amyoplasia involving only the upper limbs or only involving the lower limbs with review of the relevant differential diagnoses

Of individuals with Amyoplasia, 16.8% (94/560) involve only the upper limbs (Upper Limb Amyoplasia-ULA) and 15.2% (85/560) involve only the lower limbs (Lower Limb Amyoplasia-LLA). The accompanying paper deals with other forms of Amyoplasia [Hall et al., 2013] and discusses etiology. An excess of one of monozygotic (MZ) twins is seen in both groups (ULA 4/94 (4.3%), LLA 5/85 (5.9%)), gastrointestinal (GI) abnormalities thought to be of vascular origin (bowel atresia and gastroschisis) (ULA 16/94 (17%), LLA 4/85 (4.7%)), small or partial absence of digits (ULA 6/94 (6.2%), LLA 8/85 (9.4%)), and umbilical cord wrapping around the limbs at birth (ULA 3/94 (3.2%), LLA 7/85 (8.2%)) (severe enough to leave a permanent groove). Pregnancy complications occurred in 42/60 (70%) of ULA and 36/54 (67%) of LLA. Prenatal diagnosis, after ultrasound usage became routine, occurred in only 7/25 (28%) of ULA and 5/12 (12%) of LLA. This series may represent an over estimate of the complications and associations occurring in ULA and LLA. Differential diagnoses separating LLA from the genetic forms of "lower limb only" arthrogryposis and ULA from "upper limb only" genetic forms of arthrogryposis and Erb's palsy is provided.