Characteristics of cataract in 26 patients with myotonic dystrophy from 3 pedigrees

Jingjing SU; Xu CHEN; Zhiqiang DONG; Huijun XIE

ABSTRACT

BACKGROUND:

Cataract is not the necessary symptom for myotonic dystrophy(DM).But it may be the early and even only clinical symptom of DM.Molecular diagnosis can provide the important evidence for the diagnosis of DM.

OBJECTIVE:

To explore the characteristics of cataract in 26 patients with myotonic dystrophy of 3 pedigrees from Shanghai Songjiang area.

DESIGN:

Analysis on the Genealogy of Pedigree.

SETTING:

Department of Neurology,Shanghai Changhai Hospital.

PARTICIPANTS:

Twenty-six patients of 3 pedigrees,aged 7 to 71 years old,which were preliminarily diagnosed as DM patients or were suspicious DM patients,admitted to Department of Neurology,Shanghai Changhai Hospital between May 2001 and August 2003,were recruited in this study.Among the involved patients,13 corresponded to the clinical diagnosis standard from Practical Neurology,and the other 13 patients have adverse symptoms and (or) body signs of partial or mild DM,suspecting with DM patients.

METHODS:

①Peripheral blood of 1 mL was taken and genome DNA was extracted.By using a thermocycler,a polymerase chain reaction (PCR) was carried out to examine the CTG repeats according to criteria of molecular diagnosis (CTG repeats from 80-3350).②In addition,slit-lamp examination for specific lens opacity was carried out and the association between DM and cataract was analyzed.MAIN OUTCOME

MEASURES:

①CTG trinucleotide repeat numbers.②Association between DM and cataract.

RESULTS:

Of the 26 patients,25 participated in the final analysis except 1 who suffered from sterility clinically.①25 patients were consistent with the molecular diagnostic criteria of DM (CTG repeats from 80-3 350).The remaining 1 with CTG repeats of 13 was clinically sterility and therefore belonged to the normal individual.The (CTG)n triplet repeats of 17 patients with cataract were 2380±80,while 8 patients with cataract were 2298±105(P＞0.05).②Cataract was characterized as iridescent lens opacity or blue posterior cortical lens opacity in 17 patients.Among the 17 patients,cataract in 8 patients was the only early clinical sign whose(CTG) n triplet repeats were higher than the normal ones.

CONCLUSION:

In the pedigrees with DM patients,characteristic cataract,as a main and even only early clinical sign,will provide important clinical evidence for the early diagnosis of DM.