Cartilage hair hypoplasia: characteristics and orthopaedic manifestations.

Patrick Riley,Martin S Dicintio,Kevin A Strauss,D Holmes Morton,Dennis S Weiner,Bonnie Leighley,David Jonah,Michael B Bober

doi:10.1007/s11832-015-0646-z

Abstract

PurposeCartilage hair hypoplasia (CHH) is a rare metaphyseal chondrodysplasia characterized by short stature and short limbs, found primarily in Amish and Finnish populations. Cartilage hair hypoplasia is caused by mutations in the RMRP gene located on chromosome 9p13.3. The disorder has several characteristic orthopaedic manifestations, including joint laxity, limited elbow extension, ankle varus, and genu varum. Immunodeficiency is of concern in most cases. Although patients exhibit orthopaedic problems, the orthopaedic literature on CHH patients is scant at best. The objective of this study was to characterize the orthopaedic manifestations of CHH based on the authors’ unique access to the largest collection of CHH patients ever reported.MethodsThe authors examined charts and/or radiographs in 135 cases of CHH. We analyzed the orthopaedic manifestations to better characterize and further understand the orthopaedic surgeon’s role in this disorder. In addition to describing the clinical characteristics, we report on our surgical experience in caring for CHH patients.ResultsGenu varum, with or without knee pain, is the most common reason a patient with CHH will seek orthopaedic consultation. Of the cases reviewed, 32 patients had undergone surgery, most commonly to correct genu varum.ConclusionThis paper characterizes the orthopaedic manifestations of CHH. Characterizing this condition in the orthopaedic literature will likely assist orthopaedic surgeons in establishing a correct diagnosis and appreciating the orthopaedic manifestations. It is important that the accompanying medical conditions are appreciated and evaluated.Electronic supplementary materialThe online version of this article (doi:10.1007/s11832-015-0646-z) contains supplementary material, which is available to authorized users.

Highlights

McKusick et al [1], in an extensive study of the Old Order Amish community in eastern Pennsylvania, clearly elucidated in 77 cases a distinct type of short-limb dwarfism termed cartilage hair hypoplasia, known as McKusick metaphyseal chondrodysplasia
Purpose Cartilage hair hypoplasia (CHH) is a rare metaphyseal chondrodysplasia characterized by short stature and short limbs, found primarily in Amish and Finnish populations
Cartilage hair hypoplasia is caused by mutations in the RMRP gene located on chromosome 9p13.3

Summary

Introduction

McKusick et al [1], in an extensive study of the Old Order Amish community in eastern Pennsylvania, clearly elucidated in 77 cases a distinct type of short-limb dwarfism termed cartilage hair hypoplasia, known as McKusick metaphyseal chondrodysplasia. Cartilage hair hypoplasia (CHH) has been reported in many countries and many peoples outside the Amish. The largest population of cases outside the Amish community is found in Finland, where Makitie in 1992 described the incidence as roughly 1:23,000 live births [15]. Morbidity and mortality to varicella is clearly increased in CHH, but there is no apparent increase in susceptibility to severe or fatal infections with other viruses. Makitie et al [23] in 1999 reported an increased incidence of non-Hodgkin lymphoma and an excess risk of basal cell carcinoma in CHH. Anemia is commonly encountered and significantly correlated with the severity of immunodeficiency and growth failure

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