Young adults with cystic fibrosis are shorter than healthy peers because their parents are also short

Abstract

The aim of this study was to evaluate whether cysticfibrosis (CF) patients achieve a final height (FH) similarto the healthy population and/or appropriate for theirgenetic potential.FHs of the patients were compared with both therespective target heights (THs) and the FHs of age-matched healthy adults living in the same geographicareas, who served as controls. Patients’ THs were alsocompared with controls. Heights of both patients andtheir parents were measured with the same portableHarpenden stadiometers and by the same personsaccording to a standardised technique [4]. Definition ofFH in the CF series was based on two criteria: bone ageof at least 18 (boys) or 17 years (girls) and completepubertal development. TH was calculated by father’sheight + mother’s height ± 13 / 2.Patients were genotyped by screening for the ninedifferent mutations affecting the CFTR gene repre-senting more than 80% of CF carriers in the WesternEuropean population [5].The control population consisted of 371 young adultsaged 18–20 years (130 males, 241 females) covering thetwo regions of origin of the CF patients admitted to thisstudy, namely Sicily and Calabria. Auxological data ofcontrols were collected to draw up Italian growth chartsfor height, weight and body mass index (BMI) [3].Heights were assessed with the same portable Harpen-den stadiometers, by the same persons who measuredthe CF patients and their parents and according to thesame technique [4].In boys with CF, the average FH was comparable toboth parental height and TH (Fig.1). When comparedwith control stature, the patients’ FH was lower (Fig. 1).In girls with CF, the mean FH was very close to bothmaternal stature and TH (Fig. 2). When compared tocontrol adult height, however, the patients’ FH waslower (Fig. 2).In both sexes, TH was lower than control FH due tothe fact that both fathers and mothers of CF patientswere shorter than controls of the respective sex. On thecontrary, when compared with their sons and daughters,patient parents had a superimposable stature (Fig. 1 andFig. 2).In the overall CF series, patient FH was positivelyrelated to TH (r =0.55; P <0.001). A positive re-lationship was also found between patients’ FHs andforced expiratory volume in 1 s (r =0.25; P <0.05). Norelationship was found between patient FH and eitherBMI, pancreatic enzyme capsule intake, age at diagnosisor genotype. In CF patients, the BMI was lower thanthat of controls (19.8±1.8 vs. 22.4±1.9; P <0.0005).Our data have shown that even nowadays, CFpatients achieve a FH which remains slightly below thatof controls, despite clinical impressions and demon-strated improvements during the last 20 years [1, 2,6].Patient FHs were mainly conditioned by parental stat-ures, whereas the prognostic role of other factors wasless important. Our results might suggest the hypothesisof abnormal parental height in CF secondary to carryingthe CFTR gene, although the mechanism responsiblefor this auxological impairment is not clear.We conclude that FH in CF is lower than thatrecorded in healthy young adults living in the samegeographic regions; patient FH is superimposable tothat of their parents and strongly related to it; TH of CFpatients is lower than control stature and FH in CF ismainly conditioned by TH, at least in a selected popu-lation consisting of patients who are able to achieve 20years of age.