Purpose

To describe the phenotypic spectrum of a large cohort of albino patients, to investigate the relationship between the ocular abnormalities and the visual acuity (VA), and to define diagnostic criteria for the white population. We also estimated the prevalence of albinism in The Netherlands.

Design

Retrospective cohort study.

Participants

We investigated the phenotype of 522 patients with albinism from the databases of Bartiméus (452 patients), Leiden University Medical Center (44 patients), and the Academic Medical Center Amsterdam (26 patients).

Methods

We collected clinical, genetic, and electrophysiologic data of patients with albinism. We used grading schemes for iris translucency, fundus hypopigmentation, and foveal hypoplasia.

Main Outcome Measures

Visual acuity, nystagmus, iris translucency, fundus pigmentation, foveal hypoplasia, and misrouting.

Results

Nystagmus was absent in 7.7% (40/521), iris translucency could not be detected in 8.9% (44/492), 3.8% (19/496) had completely normal fundus pigmentation, 0.7% (3/455) had no foveal hypoplasia, and misrouting was not established in 16.1% (49/304). The VA varied from −0.1 to 1.3 logarithm of the minimum of angle of resolution (logMAR). The foveal hypoplasia grading correlated best with the VA (r = 0.69, P < 0.001), whereas iris translucency, fundus pigmentation, and misrouting did not predict the VA significantly. We estimated a prevalence of albinism in The Netherlands of at least 1:12 000.

Conclusions

None of the characteristics of albinism were consistently present in our cohort. To be able to distinguish albinism from other conditions with similar ocular features, especially in northern and western European countries, we propose major and minor clinical criteria. Major criteria would be (1) foveal hypoplasia grade 2 or more, (2) misrouting, and (3) ocular hypopigmentation, either iris translucency or fundus hypopigmentation grade 2 or more. Minor criteria would be (1) nystagmus, (2) hypopigmentation of skin and hair, (3) grade 1 fundus hypopigmentation, and (4) foveal hypoplasia grade 1. We propose that 3 major criteria or 2 major and 2 minor criteria are necessary for the diagnosis. In the presence of a molecular diagnosis, 1 major criterion or 2 minor criteria will be sufficient.

中文翻译：

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白化病的表型谱

目的

为了描述一大批白化病患者的表型谱，调查眼部异常和视敏度（VA）之间的关系，并确定白人群体的诊断标准。我们还估算了荷兰的白化病患病率。

设计

回顾性队列研究。

参加者

我们从Bartiméus（452例），Leiden大学医学中心（44例）和阿姆斯特丹学术医学中心（26例）的数据库中调查了522例白化病患者的表型。

方法

我们收集了白化病患者的临床，遗传和电生理数据。我们使用了虹膜半透明，眼底色素沉着和中央凹发育不全的分级方案。

主要观察指标

视力，眼球震颤，虹膜半透明，眼底色素沉着，中央凹发育不全和误行。

结果

7.7％（40/521）中没有眼球震颤，8.9％（44/492）中没有检测到虹膜半透明，3.8％（19/496）的眼底色素沉着完全正常，0.7％（3/455）没有中央凹发育不全，未确定路线错误的比例为16.1％（49/304）。VA在最小分辨角（logMAR）的-0.1至1.3对数之间变化。中央凹发育不全的分级与VA最佳相关（r  = 0.69，P <0.001），而虹膜半透明，眼底色素沉着和路线错误并不能很好地预测VA。我们估计荷兰的白化病患病率至少为1:12 000。

结论

在我们的队列中，白化病的特征均未始终存在。为了能够将白化病与具有相似眼功能的其他疾病区分开来，尤其是在北欧和西欧国家，我们提出了主要和次要临床标准。主要标准是（1）2级或更高的中央凹发育不全；（2）误行路线；（3）2级或更高的虹膜半透明或眼底色素减退的眼部色素减退。次要标准为（1）眼球震颤，（2）皮肤和头发色素沉着不足，（3）1级眼底色素沉着不足和（4）中央凹发育不全1级。我们建议需要3个主要标准或2个主要标准和2个次要标准。用于诊断。在进行分子诊断的情况下，一个主要标准或两个次要标准就足够了。