Hemoglobin screening:
response of a Brazilian community
to optional programs
Triag e m d e he mo g lo b ino p atias:
re sp o sta d e uma c o munid ad e b rasile ira
a p ro g ramas o p c io nais
1 Departam en to de Gen ética M éd ica, Facu ld ad e d e Ciên cias M éd icas, Un iversid ad e Estad u al d e Cam p in as, C. P. 6111, Cam p in as, SP 13081-970, Brasil.
An ton io Sérgio Ram alh o 1
Roberto Ben ed ito d e Paiva e Silva1 Rosa Ch elm in sk y Teixeira1 M arian e Bern ad ete Com p ri1
Abst ract Th e efficien cy an d th e viability of th ree h em oglobin screen in g p rogram s w ere in vesti-ga t ed . Th ey w ere offered on a v olu n t a ry b a sis t o a Bra z ilia n p op u la t ion a n d st a rt ed w it h t h e an alysis of blood d on ors, p regn an t w om en an d st u d en t s. Th e h em oglobin screen in g w as d on e t h rou gh op t ion a l ex a m s w h ich in clu d ed elect rop h oresis of h em oglob in a n d com p lem en t a ry h em atological tests. A total of 13,670 p eop le w ere tested over a p eriod of 39 m on th s an d a total of 644 in d iv id u als w ith h ered itary h em oglobin d isord ers w ere d etected – 4.7% of th e sam p les ex -am in ed . Th e p rogr-am s sh ow ed satisfactory in d icators of viability an d efficien cy, exp ressed by th e sign ificative p rop ortion of exam s p erform ed am on g th e p roban d s an d th eir relatives.
Key words Hem oglobin op ath ies; Gen etic Screen in g; Gen etic Cou n selin g; Gen etics
Resumo Foram testad as a viabilid ad e e a eficiên cia d e três p rogram as d e triagem d e h em oglo-bin op atias. Os p rogram as foram oferecid os volu n tariam en te a u m a p op u lação brasileira e in i-ciaram com o exam e d e d oad ores d e san gu e, gestan tes e escolares d os en sin os fu n d am en tal e m é-d io. A triagem é-d as h em oglobin op atias foi realiz aé-d a m eé-d ian te ex am es op cion ais, rep resen taé-d os p ela eletroforese d e h em oglobin as e exam es com p lem en tares. Um total d e 13.670 p essoas foram in vestigad as em u m p eríod o d e 39 m eses, d iagn ostican d o-se 644 p ortad ores d e alterações h ered i-t á ria s d a h em oglob in a – 4,7% d a a m osi-t ra ex a m in a d a . Os p rogra m a s m osi-t ra ra m in d ica d ores satisfatórios d e viabilid ad e e d e eficiên cia, exp ressos p ela p rop orção sign ificativa d e exam es rea-lizad os en tre os p rop ósitos e os seu s p aren tes.
Introduction
Hem oglob in op ath ies, esp ecially sickle cell syn -d ro m e s, h e m o glo b in C, a n -d βt h a la sse m ia a re co m m o n in Bra zil b e ca u se o f t h e p o p u la t io n’s e t h n ic co m p o sit io n (Sa lza n o & To n d o, 1982; Ra m a lh o, 1986; Na o u m e t a l., 1987). Alt h o u gh th e im p lem en tation of h em oglob in op ath y p rogra m s in La tin Am erica h a s b een reco m m en d -e d b y t h -e Wo r ld H-e a lt h Orga n iza t io n ( WH O, 1983), t h e Th ird Wo r ld Aca d e m y o f Scie n ce ( TWAS, 1986), a n d t h e Pa n - Am e r ica n He a lt h Orga n iza t io n (OPS, 1987), syst e m a t ic scre e n -in g o f h e t e ro zygo t e s fo r ge n e t ic co u n se l-in g -in Brazil is still very lim ited an d is on ly p erform ed in a few u n iversity cen ters. Th e WH O Co m m it-tee for th e Preven tion an d Con trol of Hem oglob in o p a t h ie s h a s a ga in re co m m e n d e d t h e im p le m e n t a t io n o f co m m u n it y h e m o glo b in o p a -t h y p ro gra m s in La -t in Am e r ica , e sp e cia lly in Bra zil (Pen ch a sza d eh , 1993).
Still, th e su ccess o f a co m m u n ity h em o glob in o p a t h y p ro gra m d e p e n d s o n t h e p o p u la t io n’s re ce p t ivit y t o su ch su r ve ys. It is im p o r -t a n -t -t o e va lu a -t e -t h e re su l-t s, sin ce re ce p -t ivi-t y h in ge s o n so cio e co n o m ic, p sych o lo gica l, a n d cu lt u ra l fa ct o r s. In d e e d , a s Bowm a n (1991) co m m e n t e d , p o p u la t io n p r o gra m s a re o ft e n co n ce ive d in a t h e o re t ica l, id e a lize d wo rld . In p ra ct ice, h owe ve r, t h e y a re ca r r ie d o u t in t h e very d ifferen t rea l wo rld .
Th e p resen t stu d y focu sed on th e efficien cy o f t h re e vo lu n t a r y h e m o glo b in scre e n in g p ro -gra m s d e ve lo p e d in a Bra zilia n p o p u la t io n , startin g with b lood testin g in p regn an t wom en , b lo o d d o n o rs, a n d stu d en ts.
Sampling and methods
Th e p ro gra m s we re d e ve lo p e d in t h e St a t e o f Sã o Pa u lo, wh o se p o p u la tio n h a s a n a p p re cia -b le n u m -b e r o f Afr ica n (h e m o glo -b in s S a n d C) a n d It a lia n d e sce n d a n t s (βt h a la sse m ia ). A t o -t a l o f 9,196 b lo o d d o n o r s, 2,209 p re gn a n -t wo m e n , a n d 2,074 st u d e n t s we re in vit e d fo r scre e n in g a t t h e St a t e Un ive rsit y o f Ca m p in a s (Un ica m p ) ove r a p e r io d o f 39 m o n t h s. Blo o d d o n o rs a n d p regn a n t wo m en were recru ited a t t h e u n ive rsit y h o sp it a l a n d st u d e n t s a t p u b lic sch o o ls in t h e co m m u n it y. Mo st o f t h e se in d i-vid u a ls we re o f low so cio e co n o m ic st a t u s. Scre e n in g fo r h e m o glo b in o p a t h ie s wa s p e r -fo rm e d b y sta n d a rd m e th o d s: co m p le te b lo o d cou n t, h em oglob in electrop h oresis in cellu lose a ce t a t e - a lka lin e p H , re d b lo o d ce ll o sm o t ic fra gility, co n firm a tio n o f β-th a la ssem ia tra it by in crea sed H b A2fra ctio n (H b A2q u a n tifica tio n
by th e u su al elu tion m eth od , after electrop h ore-sis), co n firm a tio n o f h e m o glo b in S by so lu b ilit y t e s t s, a n d c o n fir m a t io n o f fe t a l h e m o glo b in b y t h e a lka lin e d e n a t u ra t io n t e st (Ra m a -lh o, 1986). βt h a la sse m ia wa s n o t in ve st iga t e d a m on g b lood d on ors, sin ce th is con d ition gen -era lly correla tes with sign ifica n t a n em ia . Ca ses th a t co u ld n o t b e d ia gn o sed by th ese sta n d a rd m e t h o d s we re su b m it t e d t o sp e cific t e st s, in -clu d in g DNA a n a lysis. Mo le cu la r a n a lysis wa s p e r fo r m e d b y D N A a m p lifica t io n (PCR) fo llowed by restriction en zym e d igestion a n d sin -gle - st ra n d e d co n fo r m a t io n a l p o lym o r p h ism a n a lysis (SSCP).
In d ivid u a ls we re a ske d t o p a r t icip a t e vo l-u n t a rily in t h e p ro gra m s. Pa re n t a l p e rm issio n wa s re q u ire d fo r h igh sch o o l st u d e n t s. Th o se fo u n d t o b e h e m o glo b in t ra it ca r r ie r s we re a sked to b rin g th eir p a rtn ers, p a ren ts, ch ild ren (in clu d in g n e wb o r n s), a n d o t h e r re la t ive s fo r in ve st iga t io n . All t h e a b ove - m e n t io n e d t e st s were p erfo rm ed o n th ese in d ivid u a ls.
Pre n a t a l fe t a l d ia gn o sis wa s n o t o ffe re d t o h igh - r isk co u p le s, sin ce Bra zilia n le gisla t io n fo rb id s th era p eu tic a b o rtio n in th ese ca ses. All o th er la b o ra to ry tests, a s well a s m ed ica l trea t-m en t a n d gen etic co u n selin g, wh en n ecessa ry, were p rovid ed free o f ch a rge.
In d ivid u a l a n d fa m ily in t e re st in ge n e t ic co u n selin g wa s eva lu a ted o b jectively b a sed o n th e p ercen ta ge o f screen ed h eterozygo tes wh o b ro u gh t th eir p a rtn ers, ch ild ren , o r o th er rela tives for lab oratory tests. Th ey h ad received op -t io n a l a n d in d ivid u a lize d ge n e -t ic co u n se lin g a ft e r e va lu a t io n b y a n in t e rd iscip lin a r y t e a m con sistin g of gen eticists, p sych ologists, an d so-cia l wo rke r s. Ge n e t ic co u n se lin g h a d b e e n co m p le t e d wit h a n id e n t ifica t io n ca rd a n d e x-p la n a tory b ooklet a b ou t h em oglob in d isord ers su p p lied to ea ch su b ject.
Sym p tom a tic in d ivid u a ls referred by p h ysi-cia n s in t h e co m m u n it y we re a lso t e st e d (n = 185). Pa re n t s, sib lin gs, p a r t n e rs, a n d ch ild re n o f p o sitive h em o glo b in d iso rd er p a tien ts d ia gn o se d ign t h is gro u p we re ign vit e d fo r e xa m ign a -tion (n = 368). β-th alassem ia trait was th e m ain clin ica l h yp o th esis, fo llowed by sickle cell syn -d rom es.
Results
wa s o b se r ve d . Ta b le 1 sh ows t h e fre q u e n cy o f h e re d it a r y h e m o glo b in d e fe ct s d ia gn o se d in th e p o p u la tio n sa m p les.
Fo u r t e e n ca se s o f ch ro n ic h e m o lyt ic a n e -m ia (9 SS, 3 SC, 1 TT, a n d 1 CC) a t a ge s fro -m fo u r m o n t h s t o 35 ye a r s (X = 9.8 ye a r s) a re o f sp e cia l in t e re st . Of t h e 630 h e t e ro zygo t e s, 378 we re 15 ye a r s o ld o r o ld e r, a n d o f t h e se, 228 (60%) a gre e d t o re ce ive ge n e t ic co u n se lin g. Ra t e o f a cce p t a n ce o f ge n e t ic co u n se lin g wa s 64.5% a m o n g wo m e n a n d 50.6% a m o n g m e n (χ2= 4.29; 0.02<p <0.05).
Twen ty a t-risk h eterozygo u s co u p les (11 AS x AS, 5 AS x AC, 2 AT x AT, 1 AC x AC, a n d 1 AS x AT) were d ia gn o sed . Th ese co u p les h a d n o t re-ce ive d p re vio u s ge n e t ic co u n se lin g, a n d n in e o f th em h a d a ch ild with a clin ica lly sign ifica n t h em o glo b in o p a th y (7 SS, 1 SC, a n d 1 CC).
As a d d it io n a l in fo rm a t io n fro m t h is st u d y, fo u r ca se s o f p e rsiste n t h e re d ita r y fe ta l h e m o glo b in a n d t wo ca se s o f Ca m p e rd own h e m o -glob in were d ia gn osed by DNA a n a lysis a m on g th e p regn a n t wo m en .
Ta b le 2 sh ows so m e p ro gra m e fficie n cy in -d icators.
Discussion
Th e first an d p erh ap s m ost im p ortan t asp ect to e m p h a size wh e n d iscu ssin g t h is st u d y is t h e h igh re ce p t ivit y o f a Bra zilia n co m m u n it y t o
h e a lt h p ro gra m s o ffe re d o n a vo lu n t a r y, n o n -co e rcive b a sis, a s re -co m m e n d e d b y t h e Sã o Pa u lo Sta te Med ica l Co d e o f Eth ics (CREMESP, 1988). Pro gra m s sh owed sa tisfa cto ry efficien cy in d icators, exp ressed by th e sign ifican t p rop or-tio n o f tests p erfo rm ed . However, th e p ro gra m fo cu sin g o n p re gn a n t wo m e n wa s m o re e ffe c-t ive c-t h a n c-t h o se scre e n in g b lo o d d o n o r s a n d stu d en ts, as evalu ated by th e p ercen tage of rel-a t ive s wh o vo lu n t e e re d fo r t e st s. Th e gro u p o f sym p t o m a t ic in d ivid u a ls re fe r re d b y p h ysi-cia n s fro m t h e co m m u n it y wa s p a r t icu la r ly u se fu l fo r d ia gn o sis o f h e m o glo b in d e fe ct s. Th is stra tegy th u s d eserves sp ecia l a tten tion in co m m u n ity-b a sed p ro gra m s.
Tab le 1
Diag no se d he mo g lo b ino p athie s in the p o p ulatio n samp le s (in p e rc e ntag e s).
Population samples Hemoglobin defects
AS AT AC SS TT SC CC To tal
Pre g nant wo me n (n = 2,209) 2.4 0.8 0.4 3.6
Husb and s* (n = 45) 2.2 2.2 4.4 8.8
Ne wb o rn c hild re n* (n = 60) 33.3 11.7 3.3 1.7 50.0
O the r c hild re n* (n = 85) 37.6 5.9 9.4 1.2 1.2 55.3
Sib ling s* (n = 260) 28.5 13.0 5.4 0.8 47.7
Blo o d d o no rs (n = 9,196) 1.0 0.3 1.3
Sp o use s* (n = 30) 10.0 3.3 13.3
Child re n* (n = 61) 45.9 1.6 3.3 50.8
Stud e nts (n = 1,118) 0.6 1.2 0.2 2.0
Pare nts and sib ling s* (n = 53) 7.5 37.7 45.2
Sub -To tal (n = 13,117) 2.4 0.8 0.5 0.03 0.01 0.01 3.74
Ind ivid uals re fe rre d b y p hysic ians 11.2 13.4 3.0 0.9 0.5 29.0 and re lative s (n = 553)
Total(n = 13,670) 2.7 1.3 0.6 0.07 0.01 0.02 0.01 4.71
AS = sic kle c e ll trait; AT = β-thalasse mia trait; AC = he mo g lo b in C trait; SS = sic kle c e ll ane mia; TT = β-thalasse mia majo r; SC = he mo g lo b in SC d ise ase ; CC = he mo g lo b in C d ise ase .
* Re lative s o f he te ro zyg o te s.
Tab le 2
Pro g ram e ffic ie nc y ind ic ato rs.
Indicator Pregnant women Blood donors Students
Co mp lianc e (% ) 100 100 54
Partne r te sting * (% ) 56 33 –
Pare nt te sting * (% ) – – 65
Te sting o f c hild re n and / o r 90 60 65 o the r re lative s* (% )
Me an numb e r o f ind ivid uals 5.6 0.76 2.4 e xamine d fo r e ac h he te ro zyg o te
References
BOWMAN, J., 1991. Pre n a t a l scre e n in g fo r h e m o glo -b in o p a th ie s. Am erican Jou rn al of Hu m an Gen et-ics, 48:433-438.
CREMESP (Co n se lh o Re gio n a l d e Me d icin a d o Est a -d o -d e Sã o Pa u lo ), 1988. Cód igo d e Ética M éd ica. São Pau lo: CREMESP.
GRANDA, H .; GISPERT, S.; DORTICOS, A.; MARTIN, M.; CUADRAS, Y.; CALVO, M.; MARTINEZ, G.; ZA-YAS, M . A.; OLIVA, J. A. & H ERED ERO, L., 1991. Cu b a n p ro gra m m e fo r p re ve n t io n o f sickle ce ll d isease. Lan cet,337:152-153.
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Pren a ta l screen in g for h em oglob in op a th ies h a s se ve ra l p ra gm a t ic a d va n t a ge s (Rowle y e t a l., 1991). Pre gn a n t wo m e n a lre a d y h a ve ro u -t in e b lo o d -t e s-t s in -t h e p re n a -t a l p e r io d , a n d d u r in g p re gn a n cy wo m e n a re m o re a wa re o f th eir own h ealth an d th at of th eir ch ild ren . Pren atal screePren iPren g for h em oglob iPren op ath ies iPren oth -er co u n tries, su ch a s th e Un ited Sta tes (Rowley et a l., 1991), Cu b a (Gra n d a et a l., 1991), Greece (Lo u ko p o u lo s, 1985), Ca n a d a (Scr ive r e t a l., 1984), a n d Ita ly ( Ten tori & Ma rin u cci, 1983) a l-so p rovid ed satisfactory resu lts. However, th ese p ro gra m s co n d u ct e d in t h e No r t h e r n He m isp h ere in clu d ed th e p o ssib ility o f feta l d ia gn o -sis a n d o p t io n a l t h e ra p e u t ic a b o r t io n in t h e ir o b je ctive s. Th e a d va n ta ge s a n d d isa d va n ta ge s o f p re n a ta l scre e n in g fo r h e m o glo b in o p a th ie s h a ve b e e n t h o ro u gh ly d iscu sse d b y Bowm a n (1991) a n d Lo a d er et a l. (1991)
Po p u la tio n screen in g is extrem ely va lu a b le fo r in it ia t in g e a rly t re a t m e n t , a n d in t h is ca se fa m ilie s m a y b e co m e fu lly p re p a re d fo r t h e m a n a ge m e n t o f b a b ie s wit h se rio u s h e m o glo -b in o p a t h ie s. So m e so cie t ie s o ffe r p re n a t a l d i-agn osis, b u t even if th is is n ot th e case, in Brazil th ere a re en orm ou s a d va n ta ges to su ch ed u ca -tio n a l p ro gra m s.
Acce p ta n ce o f o p tio n a l ge n e tic co u n se lin g b y h e t e ro zygo t e s (60%) wa s co n sid e re d sa t is-fa ct o r y a n d wa s sign ifica n t ly h igh e r a m o n gst wo m e n . Howe ve r, it wa s lowe r t h a n t h a t o b -se r ve d b y Rowle y e t a l. (1991) in th e Ro ch e ste r
p ro gra m in t h e Un it e d St a t e s (69%) (χ2= 4.94;
0.02<p <0.05). Sin ce th e ge n e tic co u n se lin g o f-fered in th e Ca m p in a s p rogra m s h a d essen tia lly ed u cation al ob jectives, a com p lem en tary in -stru ction leaflet was given to h eterozygotes, ex-p la in in g th eir h em o glo b in d efect in d eta il. Ac-co rd in g t o Ke ssle r (1989), ge n e t ic Ac-co u n se lin g p rogram s are m ore efficien t wh en th e goals are e d u ca t io n a l ra t h e r t h a n e u ge n ic. Th e m o st gra tifyin g sh o rt-term resu lt o f th e p ro gra m s in Cam p in as was th e in creased com m u n ity aware-n ess co aware-n ceraware-n iaware-n g h em o glo b iaware-n d iso rd ers.
Fro m t h e clin ica l p o in t o f vie w, a n o t h e r gra t ifyin g re su lt wa s t h e d ia gn o sis a n d t re a t -m e n t o f 14 ca se s o f ch ro n ic h e -m o lyt ic a n e -m ia an d 178 β-th alassem ia trait carriers, m an y with h yp och rom ic an d m icrocytic an em ia. Alth ou gh h e m o glo b in o p a t h ie s a re n o t cu ra b le, t h e y a re t re a t a b le, re su lt in g in im p rove d q u a lit y o f life fo r p a t ie n t s. Fo r e xa m p le, su c h sim p le m e a su re s a s va ccin a t io n a n d p ro p h yla ct ic a d m in -ist ra t io n o f p e n ic illin t o c h ild re n wit h sic kle c e ll syn d ro m e s in cre a se t h e ir life e xp e ct a n cy ( Vich in sky e t a l., 1988; Wo n g e t a l., 1992). Ne o n a t a l scre e n in g is t h u s a n o p t io n fo r e a rly trea tm en t o f h em o glo b in o p a th ies.
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