下颌骨发育不良伴B型脂肪营养不良(MADB)是一种罕见的早衰性疾病,具有常染色体隐性遗传模式。MADB的特点是头发脆弱,斑驳,萎缩性皮肤,全身性脂肪营养不良,胰岛素抵抗,代谢并发症和骨骼特征,如发育迟缓,下颌骨和锁骨发育不全和远端指骨的肢骨溶解。MADB是由ZMPSTE24中复合杂合或纯合突变导致的锌金属蛋白酶ZMPSTE24活性降低引起。
2012年和2018年,对来自内陆苏里南偏远热带雨林的8名相关患者进行了畸形特征分析。进行DNA分析并记录临床特征。我们还分析了所有先前报道的来自文献(n=12)的遗传证实的MADB患者的临床特征。根据所有病例(n=20)的特征,我们将主要标准定义为所有MADB患者中85-100%的主要标准,而将次要标准定义为70-84%的患者。
所有苏里南患者都是非洲裔,并且具有相同的纯合子c.1196A>G,p。(Tyr399Cys)在ZMPSTE24基因中的错义变异,确认MADB。发现主要标准是:身材矮小,锁骨发育不全,颅骨缝合延迟闭合,高腭,下颌骨发育不全,牙齿拥挤,远端指骨的关节骨溶解,发育不良的指甲,脆弱和/或稀疏的头发,斑驳的色素沉着,萎缩性和硬化皮肤,和钙化的皮肤结节.次要标准是四肢(全身或部分)脂肪萎缩,关节挛缩和指骨缩短。根据我们详细的临床观察,以及对先前描述的案例的回顾,我们认为,如果患者表现出≥4项主要临床标准或≥3项主要临床标准和≥2项次要临床标准,则很有可能诊断为MADB.
我们报告了8名相关的苏里南患者由于ZMPSTE24中的纯合创始人突变而患有MADB。在低收入国家,用于分子遗传检测的实验室设施很少或缺乏。然而,因为诊断MADB对于指导临床管理和家庭咨询至关重要,我们定义了临床诊断标准并提出了治疗指南.
Mandibuloacral Dysplasia with type B lipodystrophy (MADB) is a rare premature aging disorder with an autosomal recessive inheritance pattern. MADB is characterized by brittle hair, mottled, atrophic skin, generalized lipodystrophy, insulin resistance, metabolic complications and skeletal features like stunted growth, mandibular and clavicular hypoplasia and acro-osteolysis of the distal phalanges. MADB is caused by reduced activity of the enzyme zinc metalloprotease ZMPSTE24 resulting from compound heterozygous or homozygous mutations in ZMPSTE24.
In 2012, and again in 2018, eight related patients from the remote tropical rainforest of inland Suriname were analysed for dysmorphic features. DNA analysis was performed and clinical features were documented. We also analysed all previously reported genetically confirmed MADB patients from literature (n = 12) for their clinical features. Based on the features of all cases (n = 20) we defined major criteria as those present in 85-100% of all MADB patients and minor criteria as those present in 70-84% of patients.
All the Surinamese patients are of African descent and share the same homozygous c.1196A > G, p.(Tyr399Cys) missense variant in the ZMPSTE24 gene, confirming MADB. Major criteria were found to be: short stature, clavicular hypoplasia, delayed closure of cranial sutures, high palate, mandibular hypoplasia, dental crowding, acro-osteolysis of the distal phalanges, hypoplastic nails, brittle and/or sparse hair, mottled pigmentation, atrophic and sclerodermic skin, and calcified skin nodules. Minor criteria were (generalized or partial) lipoatrophy of the extremities, joint contractures and shortened phalanges. Based on our detailed clinical observations, and a review of previously described cases, we propose that the clinical diagnosis of MADB is highly likely if a patient exhibits ≥4 major clinical criteria OR ≥ 3 major clinical criteria and ≥ 2 minor clinical criteria.
We report on eight related Surinamese patients with MADB due to a homozygous founder mutation in ZMPSTE24. In low-income countries laboratory facilities for molecular genetic testing are scarce or lacking. However, because diagnosing MADB is essential for guiding clinical management and for family counselling, we defined clinical diagnostic criteria and suggest management
guidelines.